{"paper_id":"41a91eef-e224-42d0-82f0-daacd5af4064","body_text":"The carbonate-derived δ¹³C and δ¹⁸O records as proxies for Mid-Carboniferous climate in northwestern Mexico | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article The carbonate-derived δ¹³C and δ¹⁸O records as proxies for Mid-Carboniferous climate in northwestern Mexico Salvador Gutiérrez Reyes, Juan Moisés Casas Peña, Rafael Villanueva Olea, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6165627/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The Paleozoic climate variations are preserved in δ 13 C and δ 18 O records from marine carbonate rocks. These records can be modified by diagenesis derived from the environmental processes of a particular region. The simultaneous evaluation of δ 13 C carb and δ 18 O carb can help to identify alterations and to improve environmental interpretations. The Late Paleozoic Ice Age began during the Carboniferous and coincided with the early stages of the Pangea assembly. The paleoceanographic and paleoclimatic changes affected the region of central Sonora, Mexico, at the westernmost embayment of the Rheic Ocean. To explore the relationship between local environmental processes and the early diagenesis imprint in the isotopic records, we estimate the δ 13 C carb and δ 18 O carb values in 54 rock samples from Sonora. 38 samples were from the Sierra Agua Verde region, and 16 samples from the Cerro Las Rastras southern area. The early diagenetic imprint of the environmental variations suggests periods characterized by: (a) lower δ 18 O carb values which indicates heavy rains and/or riverine discharges; (b) higher δ 18 O carb values associated with droughts; (c) lower δ 13 C carb values related to enhanced upwellings and/or riverine discharges; and (d) higher δ 13 C carb values, reflecting a high productivity period. The δ 13 C carb and δ 18 O carb records from central Sonora rocks are consistent with those reported in the western USA, a region closely correlated with NW Mexico. The results of this study offer an approximation of how the environmental conditions were during the MPB in the westernmost Rheic Ocean area, and how they were related to global climatology. Mississippian Pennsylvanian Sonora Geochemistry Paleoclimatology Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 INTRODUCTION The Carboniferous is a geological period marked by significant environmental variations (Aretz et al., 2020 ; Chen et al., 2021 ). Continental drift closed the communication between Paleotethys and Rheic Ocean during the Mississippian-Pennsylvanian Boundary (MPB) (Davydov & Cózar, 2019 ), which eventually led to the Pangea supercontinent formation (Rogers & Santosh, 2004 ), a global tectonic event that culminated by the end of the Permian. During the MPB, the approach of Laurussia and Gondwana caused changes on equatorial ocean currents, transporting more heat to polar regions (Qiao & Shen, 2014; Conde et al., 2024). The movement of Gondwana around the south pole produced variations on ice covering (Caputo & Crowell, 1985 ). The proliferation of terrestrial plants, the extension of organic carbon storages as coal, and the increase in continental weathering induced a fall in atmospheric CO 2 and a global cooling trend (Ronov, 1982 ; Algeo et al., 1995 ; Chen & Sharma, 2016 ; Chen et al., 2018 ; Tian et al., 2020 ). This gave rise to the Late Paleozoic Ice Age (LPIA), one of the most severe glaciations of the Phanerozoic (Crowley, 2000 ). The LPIA event is associated with 3 glacial pulses during the Carboniferous period (Isbell et al., 2003 ). The first glacial pulse occurred during the Frasnian, potentially extending into the Tournaisian. The second glacial pulse spanned the Serpukhovian and Bashkirian stages. Finally, the third pulse began in the Kasimovian and persisted until the late Sakmarian. Changes in paleoceanography, biogeochemical carbon cycling and global temperature associated with these pulses are preserved in carbon and oxygen isotopic compositions of marine carbonates and fossils. Although diagenetic processes can modify the isotopic records of δ 13 C and δ 18 O in carbonate rocks (Marshall, 1992 ; Swart & Eberli, 2005 ; Hönig & John, 2015 ), a joint study of these proxies is an effective tool for evaluating and understanding the past environmental condition changes as well as diagenetic effects. The simultaneous evaluation of δ¹³C and δ 18 O variations in limestones from localities far from polar regions helps to understand the relationship between global and local environmental processes that affect the isotopic signatures on carbonate rocks. Villanueva-Olea et al. ( 2019 ) were the first to analyze the carbon and oxygen isotope ratios (δ¹³C and δ¹⁸O) in carbonate rocks from the La Joya section of the Sierra Agua Verde mountain range in Sonora, northwestern Mexico. The authors concluded that their isotopic records were partially congruent with the global MPB climate conditions proposed by other studies (Mii et al., 1999 , 2001 ; Saltzman, 2003 ; Liu et al., 2015 ). They also indicated that some discrepancies are due to the input 16 O enriched freshwater and 12 C by regional upwellings as causal factors. This study builds upon previous isotopic investigations by analyzing the carbon and oxygen isotope ratios (δ¹³C and δ¹⁸O) in carbonate rocks from central Sonora. We critically re-interpret the isotopic sequences reported by Villanueva-Olea et al. ( 2019 ) for the La Joya section, considering the influence of diagenesis and local environmental variations. This study also presents new carbon and oxygen isotopic data from the Rancho Nuevo Formation in the southwestern sector of Cerro Las Rastras, east of Mina de Barita in central Sonora. Samples were collected primarily from this formation, and the analysis includes a conodont biostratigraphic overview. GEOLOGICAL SETTING Mexico possesses a stratigraphic record of Carboniferous rocks. These rocks are relatively abundant and better preserved in the northwestern region of the country (e.g., Navas-Parejo, 2018 and references therein). During the Carboniferous period, most of the current State of Sonora was located much closer to the equator than it is today (Peyser & Poulsen, 2008 ). As a result, the region was submerged under tropical waters, which led to the deposition of Carboniferous calcareous rocks (Gutschick & Sandberg, 1983 ; Poole et al., 2005 ). The late Paleozoic fossils of Sonora are abundant and mainly constituted of fusulinids, foraminifers, corals, brachiopods and less common algae, radiolarians, bryozoans, and crinoids (Buitrón-Sánchez et al., 2012 ; Stevens et al., 2014 , among many others). Marine vertebrates are mostly represented by conodonts and some remains of chondrichthyans (e.g., Navas-Parejo et al., 2017 ; Martínez-Pérez et al., 2019 ; Lara-Peña et al., 2020 , 2021 , among others). Facies from two distinct marine environments characterize the region, such as: (1) shallow marine deposits, accumulated on shallow cratonic seas and continental margin platforms, which are exposed in the northern and central portions of the state (Stewart and Poole, 2000 ); and (2) the deep ocean sediments, that are grouped in the Sonora Allochthon, which mainly crops out in the central region of the state (Poole et al., 2005 ). One of the most studied areas of Sonoran Paleozoic is Sierra Agua Verde, the first study area herein. This mountain range is located in the central area of the state (Fig. 1 ). It is composed of sedimentary, igneous, and metamorphic rocks of Paleozoic, Mesozoic, and Cenozoic ages. Building upon the initial work of Poole et al. ( 1984 ), the most exhaustive geological work in Sierra Agua Verde was made by Stewart et al. ( 1999 ), who studied the Neoproterozoic (?)-Pennsylvanian interval of the succession. Their integrative work included the definition of several map units based on lithostratigraphy but mostly on biostratigraphy by means of conodonts, foraminifera, algae, corals and incertae sedis , concluding that Sierra Agua Verde Paleozoic succession represents an inner-shelf depositional environment. Conodont analysis of the La Joya section in the Sierra Agua Verde indicates the Laurussian carbonate shelf reached this region during the Late Paleozoic (Navas-Parejo et al., 2017 ). Isotopic studies by Villanueva-Olea et al. ( 2019 ) indicate that Sierra Agua Verde experienced unique paleoenvironmental conditions during the MPB. Their analysis of oxygen and carbon isotopes (δ 18 O and δ 13 C) from the section deviated from global MPB trends, such as the oxygen isotope excursion linked to polar ice sheet melting and the carbon isotope excursion at the beginning of the Pennsylvanian (Mii et al., 1999 & 2001 ; Joachimski et al., 2006 ). Instead, both δ 13 C and δ 18 O showed a decreasing trend, likely caused by freshwater input (rich in 16 O) and regional upwellings (rich in 12 C). This suggests that Sierra Agua Verde experienced distinct conditions compared to global patterns during the MPB, likely influenced by local factors like freshwater influx and upwelling. The type locality of the Sonora Allochthon crops out in the central region of Sonora (Poole et al., 2005 ; Navas-Parejo, 2018 ), known as the Barita de Sonora. The second study area herein, Cerro Las Rastras, is located within this Sonora Allochthon type locality, specifically within the Barita de Sonora area (Fig. 1 ). The Barita de Sonora area contains fossils that indicate a wide range of ages. Regarding the Carboniferous, Early Mississippian conodonts have been documented (Poole et al., 2005 ), within the Barita de Sonora area, suggesting a late Visean to Bashkirian age. Other studies using radiolarians and foraminifera indicate the presence of Late Mississippian and possibly Early Pennsylvanian ages (Poole et al., 1983 ; Bartolini, 1988 ; Bartolini et al., 1989 ). Poole & Amaya-Martínez ( 2000 ) found fusulinids, radiolarians, and conodonts representing all Pennsylvanian stages in the Rancho Nuevo Formation. Stevens et al., ( 2014 ) reported fusulinids from Desmoinesian to Virgilian in Rancho Nuevo Formation (middle Moscovian to Gzhelian). The Sonora Allochthon was affected by a deformation system developed with the approach and convergence of Laurrusia and Gondwana. This deformation began during the Mississippian period, resulting in the folding and thrusting of the rocks in the region (Poole & Perry, 1997 , 1998 ). The deformation also involved a displacement of deep-marine successions, around ~ 100–200 km northward, which resulted in overlying the Carboniferous-Permian carbonate shelf (Poole & Amaya-Martínez, 2000 ). Currently, the vestiges of this deformational event are interpreted as the western sector of the Ouachita-Marathon-Sonora Orogenic Belt (Poole et al., 2005 ). MATERIALS AND METHODS 1. Studied section 1. La Joya section La Joya section is located 30 km north of the Sonora Allochthon and constitutes one of the southernmost outcrops of the continental shelf of Laurussia (Fig. 1 ; Poole et al., 2005 ). The stratigraphic section studied was previously described by Navas-Parejo et al. ( 2017 ) and Villanueva-Olea et al. ( 2019 ). This is a 270 m-thick succession that crops out between La Joya and El Palmar streams (base: 29° 14' 29\" N, 109 ° 51' 25\" W, top: 29° 14' 25\" N, 109° 51' 3\" W). Despite partial vegetation cover, the outcrop exposes a well-preserved stratigraphic carbonate succession (Fig. 2 ). It includes beds of limestone, fine-grained sandy limestone with chert and sandstone. A detailed description of the section can be found in Villanueva-Olea et al. ( 2019 ). The biostratigraphy of the La Joya section of Sierra Agua Verde was based on the detailed study of conodonts of Navas-Parejo et al. ( 2017 ). In the lower part of the section occurs a conodont association that characterizes the Meramecian (Visean) homopunctatus-Upper texanus Zones in the western United States conodont zonation (Poole & Sandberg, 1991 ). In level LJ26, at 81.04 m, the appearance of a distinct conodont association marks the lower boundary of the Meramecian Cavusgnathus Zone (Poole & Sandberg, 1991 ). The last occurrence of Cavusgnathus unicornis morphotype β allowed the recognition of the Meramecian-Chesterian boundary at level LJ34 (101.05 m). The naviculus and unicornis Mississippian Zones were not identified due to the absence of the nominative species. However, the only occurrence of Rhachistognathus species in the La Joya section, in sample LJ38 (120.05 m), helped to identify the last two conodont biozones of the uppermost part of the Mississippian. At sample LJ40 (130.61 m), the first occurrence of the Declinognathodus noduliferus group species indicates the base of the Pennsylvanian. Villanueva Olea et al. (2019) marked the possible location of the Morrowan-Atokan boundary (aprox. Bashkirian-Moscovian boundary) at level LJ57 (223.28 m). 2. SW sector of Cerro Las Rastras Cerro Las Rastras is a key locality in central Sonora. This site preserves the tectonic vestiges of the contact between the Sonora Allochthon and the southern Laurussian continental shelf. At this locality, Carboniferous deep-ocean facies of the Sonora Allochthon, considered a synorogenic succession included in the Rancho Nuevo Formation, are well exposed (Poole & Amaya-Martínez, 2000 ; Poole & Madrid, 1988 ; Stevens et al., 2014 ). The Rancho Nuevo Formation includes deformed beds of quartzite, argillite, conglomerate, barite deposits and limestone (Stevens et al., 2014 ). Previous works with fusulinids, foraminifera and conodonts suggested a Middle Mississippian and Pennsylvanian age for these rocks (Poole et al., 1983 , 2005 ; Poole & Amaya-Martínez, 2000 ). In our study, 16 samples of limestone were collected within the area defined by the coordinates SW: 28° 55' 8\" N, 109 ° 58' 27\" W - NE: 28° 55' 34\" N, 109° 57' 0\" W (Fig. 3 ). This area is about 100 km east of Hermosillo. The exposed rocks are dark bluish gray to light gray. Some horizons exhibit yellowish, brownish, and reddish colors. Rock samples were taken from intervals with minimum visible alteration to avoid weathering and diagenetic overprint. Due to the significant deformation in this region, constructing a stratigraphic column was complicated. However, based on previous geological and biostratigraphic studies (e.g., Poole et al., 2005 ; Stevens et al., 2014 ), the sampling points were selected along the best exposed Carboniferous rocks. To corroborate the dating of the rock, the samples from Cerro Las Rastras were processed to search for conodonts. About 20 kg of rocks were dissolved according to the methodology outlined by Jeppsson et al. ( 1999 ) in a buffered acetic and formic acid solutions. Summary information about collected samples is described on Table 1 . Table 1 Localization, lithology, and biostratigraphic age based on the conodont genus or genus associations found in the collected samples of the SW sector of the Cerro Las Rastras. Samples / Formation Latitude / Longitude Lithology Conodonts genus or genus association / Biostratigraphic Age 22LR01 / Rancho Nuevo 28°55'8.74\"N/ 109°58'27.06\"W Limestone Idiognathodus, Gondolella / Middle Pennsylvanian (Desmoinesian) 22LR02 / Rancho Nuevo 28°55'9.35\"N / 109°58'25.91\"W Sandy Limestone Idiognathodus, Gondolella / Middle Pennsylvanian (Desmoinesian) 22LR03 / Rancho Nuevo 28°55'9.01\"N / 109°58'20.01\"W Limestone with chert nodules - 22LR04 / Rancho Nuevo 28°55'13.33\"N / 109°58'6.59\"W Sandy Limestone Idiognathoides, Idiognathodus, Gondolella, Streptognathodus / Middle Pennsylvanian (Desmoinesian) 22LR05 / Rancho Nuevo 28°55'26.94\"N / 109°56'58.62\"W Sandy Limestone - 22LR06 / Rancho Nuevo 28°55'28.58\"N / 109°57'0.93\"W Limestone - 22LR07 / Rancho Nuevo 28°55'27.26\"N / 109°57'2.71\"W Sandy Limestone Streptognathodus / Middle to Late? Pennsylvanian (Desmoinesian to Virgilian?) 22LR08 / Rancho Nuevo 28°55'29.20\"N / 109°57'22.67\"W Limestone Idiognathodus / Middle to Late? Pennsylvanian (Desmoinesian to Virgilian?) 22LR09 / Rancho Nuevo 28°55'29.97\"N / 109°57'16.61\"W Sandy Limestone - 22LR10 / Sierra Martínez Group (?) 28°55'34.54\"N / 109°57'14.83\"W Limestone Neopolygnathus / latest Devonian – Early Mississippian 22LR11 / Rancho Nuevo 28°55'33.06\"N / 109°57'25.55\"W Limestone Idiognathodus, Gondolella / Middle Pennsylvanian (Desmoinesian) 22LR12 / Rancho Nuevo 28°55'28.53\"N / 109°57'40.89\"W Limestone - 22LR13A / Rancho Nuevo 28°55'27.00\"N / 109°57'35.40\"W Sandy Limestone - 22LR13B / Rancho Nuevo 28°55'28.02\"N / 109°57'33.88\"W Sandy Limestone - 22LR14 28°55'26.70\"N / 109°57'22.29\"W Siltstone - 22LR15 / Rancho Nuevo 28°55'28.30\"N / 109°57'23.42\"W Sandy Limestone Idiognathodus / Middle to Late? Pennsylvanian (Desmoinesian to Virgilian?) 2. Isotopic analysis 1. Sample preparation A total of 38 sample levels of the La Joya section were involved in this study. In the case of Cerro Las Rastras, 16 sample levels were processed. About 1 g of rock sample was obtained using a diamond-tipped drill (Saltzman, 2003 ; Brand et al., 2012 ). Powder was extracted directly from the carbonate matrix, avoiding altered surfaces and calcite veins. This procedure was carrried out at the ConoLAB, Estación Regional del Noroeste of the Instituto de Geología (UNAM). 2. Stable isotope analysis Carbon and oxygen isotope analysis were performed at the Laboratory of Stable Isotope Analysis of the Unidad Académica de Ciencias y Tecnología de Yucatán-UNAM (n = 302, Sierra Agua Verde, La Joya section, averaging repetitions for each stratigraphic level) and at the Instituto de Geología-UNAM (n = 16, Cerro Las Rastras). In both cases, the analysis was carried out using a GasBench II device connected to a Thermo Scientific Delta V Plus mass spectrometer and to a Thermo Finnigan MAT 253 mass spectrometer, respectively. About 100–200 µg of powders were treated with CaCO 3 -H 3 PO 4 at 25°C to release CO 2 from carbonates. Isotopic values are presented in δ-notation and reported relative to the Vienna Pee Dee Belemnite (VDPB) standard. Reference materials used for quality control were the following: LAIE-CACO3 (δ 13 C=-18.6‰, δ 18 O=-20.7‰), LAIE-34 (δ 13 C=2.5‰, δ 18 O=-2.4‰), NBS18 (δ 13 C=-5.1‰, δ 18 O=-23.1‰), LAIE-QC (δ 13 C=1.6‰, δ 18 O=-5.6‰), IAEA-603 (δ 13 C=2.5‰, δ 18 O=-2.4‰), NBS 19 (δ 13 C=2.09‰, δ 18 O=-1.65‰), NBS 18 (δ 13 C=-4.90‰, δ 18 O=-22.69‰), LSVEC (δ 13 C=-46.44‰, δ 18 O=-26.31‰), TS (δ 13 C=2.05‰, δ 18 O=-1.79‰), CaCO3 Sigma Aldrich (δ 13 C=-8.01‰, δ 18 O=-20.92‰) and CaCO 3 Merck (δ 13 C=-46.62‰, δ 18 O=-16.12‰). The reproducibility of the measurements was better than 0.05‰ for δ 18 O and 0.06‰ for δ 13 C, for the Sierra Agua Verde samples, and better than 0.15‰ for δ 13 C and 0.12‰ for δ 18 O, for the Cerro Las Rastras samples. RESULTS 4.1. Sierra Agua Verde The δ 13 C carb and the δ 18 O carb values of the La Joya section range from − 2.88 to + 3.30‰ (δ 13 C carb mean: -2.60 to + 3.15‰) and from − 15.54 to -2.71‰ (δ 18 O carb mean: -15.46 to -3.74‰), respectively (Fig. 4 ). The Visean δ 13 C carb record is characterized by a decreasing trend from the highest values of the whole record to a value of 0.00‰, at level 75.59 m. A subsequent increase occurs to a value of 2.17‰ throughout the upper part of the Visean. Above this, a decreasing trend down to a value of -1.45‰ at level 123 m and is maintained across the Serpukhovian and the Lower Bashkirian (i.e., middle-upper Chesterian and lower Morrowan). A slight decrease in the lower part of the Pennsylvanian is capped by a positive shift of 0.67‰ at level 191 m. Finally, in the upper part of the Pennsylvanian section, the δ 13 C carb curve decreases (down to -2.60‰) followed by a return to more positive values. On the other hand, the δ 18 O carb values begin with a negative trend that reaches the lowest value of the whole record (down to -15.54‰). Later, the record shows a positive trend until almost the middle part of the Visean (Meramecian), up to a maximum of -4.67‰. Upwards, within the upper Visean (lower Chesterian) and lower Bashkirian (lower Morrowan) interval, the δ 18 O carb curve records a trend towards lower values (down to -11.89‰). Subsequently, a positive shift with an amplitude of 9.07‰ at middle Bashkirian is followed by a negative trend that continues throughout the Bashkirian-Moscovian boundary. 4.2. Cerro Las Rastras The samples from the SW sector of the Cerro Las Rastras exhibit a δ 13 C carb and the δ 13 O carb values range from − 9.65 to + 2.68‰ and from − 12.15 to + 0.46‰, respectively (Fig. 5 ). The isotopic distribution cloud of the deep-basin samples from Cerro Las Rastras is very similar to that of the shallow marine environments from Sierra Agua Verde. The oxygen and carbon isotopic records show no visible pattern in the data distribution. All data presented in this paper is available online in the Gutiérrez et al., ( 2024 ). Conodonts were identified in samples 22LR-01, 22LR-02, 22LR-04, 22LR-07, 22LR-08 22LR-11 and 22LR-15, including different genera, such as Idiognathoides , Idiognathodus, Streptognathodus and Gondolella (Table 1 ; Fig. 6 ). In particular, Idiognathodus and Streptognathodus indicate an age corresponding to the Middle to Late Pennsylvanian, a period characterized by their greatest abundance and diversification. Samples which contain only one of these genera (e.g., 22LR-7, 22LR-8, 22LR-15; Table 1 ; Fig. 6 ) may correspond to an age range between Desmoinesian and Virgilian (Middle to Late Pennsylvanian). In other hand, samples that additionally contain the genus Gondolella (e.g., 22LR-1; 22LR-2; 22LR-4; 22LR-11), a genus identified from the base of the Middle Pennsylvanian (late Atokan) and often associated with genera such as Idiognathodus and/or Streptognathodus , could constrain the age of these samples to the Desmoinesian (Middle Pennsylvanian). Therefore, the conodont genera or assemblage for each sample indicates Middle to Late Pennsylvanian age (Desmoinesian to Virgilian; Table 1 ; Fig. 6 ) for the SW sector of Cerro Las Rastras and which in several localities of the North American Mid-Continent have also been reported (e.g., Lost Branch cyclothem; Barrick et al., 2022 ; Dunn, 1970 ). Only the 22LR-10 sample contains latest Devonian to early Mississippian polygnathid conodonts, specifically of the Neopolygnathus genus (Fig. 6 ), confirming an older stratigraphic unit, previously described as carbonate shelf, which consists of Upper Devonian to Pennsylvanian rocks (Poole et al., 2008 ). Therefore, sample 22LR-10 is beyond the scope of the present study. No conodonts were found in the remaining nine samples. In addition, sample 22LR-14 is also outside the scope of this work as it is a siltstone and not a limestone. DISCUSSION 1. Impact of diagenetic alteration on isotopic δO and δC imprints Post-depositional diagenetic alteration may modify the primary isotope signal of marine carbonates. For instance, meteoric-vadose diagenesis generally causes a depletion of the carbon and oxygen isotope values, which results in a strong covariation between δ 18 O and δ 13 C values (Allan & Matthews, 2009 ; Swart, 2011 ; Di Lucia et al., 2012 ). The scatterplot of the δ 18 O and δ 13 C values for the studied samples show that these parameters have no significant correlation (La Joya: r = 0. 0001: Cerro Las Rastras: r = 0.0321). This is consistent with the lack of correlation also found by Villanueva-Olea et al. ( 2019 ) in the La Joya section (r = 0.14), where variations in signatures and absolute values occur as one ascends stratigraphically which closely resembles the new data herein documented (i.e., δ 13 C: r = 0.90; δ 18 O: r = 0.88) (Fig. 7 ). In addition, to discard analytical errors, all the above indicates that diagenetic transformations had no major impact in the δ 13 C values and they represent a primary marine signal. The records of our study are different from the global values reported in both, Carboniferous brachiopods and carbonates rocks, which range between − 2‰ and + 8‰ (Fig. 5 ) (e.g., Bruckschen et al., 2001 ; Mii et al., 2001 ; Saltzman, 2003 ; Batt et al., 2007 ; Grossman et al., 2008 ; Buggisch et al., 2008 , 2011 ; Brand et al., 2012 ; Liu et al., 2015 ; Qie et al., 2016 ). The δ 13 C carb values obtained in this study exhibit trends and absolute values comparable to those reported in limestones from West USA (Saltzman, 2003 ; Batt et al., 2007 ) (Fig. 8 ). Although the obtained δ 18 O carb record in this study reaches lower values than the documented from Carboniferous brachiopods (-8 to 0‰ from Mii et al., 1999 ; Grossman et al., 2008 ; and Brand et al., 2012 ) and Carboniferous carbonates rocks from South China (-6.9 to -3.0‰ from Zhao & Zheng, 2014), the overall trends in our δ 18 O carb are similar to those observed in the western USA (Batt et al., 2007 ; Fig. 8 ). Moreover, in the Visean interval, both records display a strong depletion (δ¹ 8 O < -10‰), which may suggest that the NW regions of Mexico and USA were affected by the same processes that controlled the isotopic signatures. According to some authors it is suggested that δ 18 O carb values < -6‰ can represent the recrystallization and isotope resetting under the influence of 18 O depleted fluids (e.g., Hayes, 1993 ; Saltzman, 2003 ). In addition, Batt et al. ( 2007 ) suggested that δ 18 O carb values lower than − 10‰ in West USA limestones indicate a diagenetic overprint. In the La Joya section, samples recording the negative shift of δ 18 O carb at the lower part of the Visean do not show visible diagenetic alteration (silicification, oxidization, and/or dolomitization). However, it should be noted that this anomaly in δ 18 O carb values coincides with the environmental model proposed by Villanueva-Olea et al. ( 2019 ), which suggest that the La Joya sediments experimented a change in the depositional setting from external platform margin to a restricted lagoon. In this sense, the depth shift on the La Joya basin could have been the major environment factor which facilitated the development of meteoric waters, triggering an enhanced input of water enriched in 16 O by fluvial and pluvial discharges (Marshall, 1992 ; Keller et al., 2004 ; Al-Mojel et al., 2018 ; Salih et al., 2019 ; Herath et al., 2022 ). Therefore, the strong decrease in δ 18 O carb records does not coincide with a significant decrease in δ¹³C carb , due to the meteoric waters that affected δ 18 O carb could have been mostly from rainwater without organic matter significative supply (e.g., Marshall, 1992 ; Al-Mojel et al., 2018 ; Salih et al., 2019 ; Herath et al., 2022 ). 2. Comparison of δC and δO records in Central Sonora Villanueva-Olea et al. ( 2019 ) estimated the δ 13 C and δ 18 O values in Sierra Agua Verde limestones. Their interpretations were not entirely congruent with the global MPB climatology proposed by other studies. Some authors suggest that the Late Paleozoic Ice Age was caused by the decrease in pCO 2 and the increase in seasonality (Raymond et al., 1989 ; Isbell et al., 2003 ; Limarino et al., 2006 ; Fielding et al., 2008 ). Thus, it would be expected that carbonate δ 18 O records present a positive excursion during MPB, due to the loss of global 16 O stored in polar ice sheets, along with a corresponding positive excursion in δ 13 C carbonate records (e.g., Mii et al., 1999 ; Mii et al., 2001 ; Batt et al., 2007 ). However, in previous oxygen and carbon isotopes analysis conducted by Villanueva-Olea et al. ( 2019 ), both δ 18 O and δ 13 C data show an opposite trend. The strong correlation between the Sierra Agua Verde previous and new records, and the isotopic data from Cerro Las Rastras (as shown in Fig. 5 ) , also in central Sonora, provides evidence of a reliable representation of the Carboniferous isotopic signal in rock and precludes methodological errors. However, it is important to mention that, according to biostratigraphic age of conodonts found in some samples from Cerro Las Rastras, the isotopic records could be reflecting the effects of the last glacial pulse of the Carboniferous, in the Late Pennsylvanian stage. Likewise, it should also be highlighted that sample 22LR-04 presents a very low δ 13 C carb value (-9.6‰), moving it away from the dispersion of most of the Cerro Las Rastras samples in Fig. 5 . A high concentration of organic matter in the sedimentary environment could explain low δ 13 C carb values ​​due to 12 C enrichment (Liu et al., 2015 ). However, we do not have any TOC studies. It would be interesting to do so in future work. If that were the case, this would be consistent with the high abundance of conodonts found at this level (240 elements per kilogram of dissolved rock) and the resulting conodont biofacies at this stratigraphic level, since they suggest deep basin sedimentary environments, where organic remains could accumulate and influence during diagenesis. 3. δ 13 C carb and δ 18 O carb records from Central Sonora and Global comparisons The δ 13 C carb and δ 18 O carb data from Sierra Agua Verde can be separated into two groups (Fig. 5 ). The first is dominated by Visean data and characterized by positive δ 13 C carb values, whereas the second grouped most of the Serpukhovian, Bashkirian and Moscovian records, and is distinguished by almost exclusively negative δ 13 C carb values. This could be explained by local and global environmental changes that occurred during the Carboniferous (Chen et al., 2018 ; Chen & Sharma, 2016 ; Villanueva-Olea et al., 2019 ). To understand the possible causes that could have defined these patterns in the distribution of isotopic values, it is necessary to comprehend the processes that affect the behavior of the isotopic ratios of oxygen and carbon in carbonate rocks. 1. Correlation between δC, δO and local processes The precipitation of carbonates occurs at or near isotopic equilibrium from natural waters. The variability of marine δ 13 C can be associated to primary productivity due to the biologic preference to 12 C (Algeo et al., 1995 ; Berner & Barron, 1984 ; Hoefs, 2018 ; Popp et al., 1986 ). Environmental parameters such as temperature, salinity, depth and substrate can affect the ocean's carbon (Bruckschen et al., 1999; Mii et al., 1999 ). However, it has been shown that their direct impact on marine δ 13 C is minimal and their main influence lies in nutrient availability for marine life to grow (Saltzman, 2005 ; Liu et al., 2015 ). δ 18 O is strongly controlled by the interactions with meteoric waters, evaporation, and water masses (Craig & Gordon, 1965 ; Hoefs, 2018 ; Horita & Wesolowski, 1994 ). In addition, early diagenetic processes can also affect the isotopic records of δ 13 C and δ 18 O in carbonated rocks (Marshall, 1992 ; Swart & Eberli, 2005 ; Hönig & John, 2015 ). Some authors suggest that the constant exposure of sediments to meteoric waters and organic matter can diminish values of δ 13 C and δ 18 O in carbonate rocks, this is due to a stabilization during early diagenesis with the light oxygen of rainwater and the 12 C enriched organic matter. Thus, the joint study of δ¹³C and δ 18 O is commonly used as a tool to help understand the processes that control the isotopic records, especially to identify the effect of diagenesis (Marshall, 1992 ; Keller et al., 2004 ; Al-Mojel et al., 2018 ; Salih et al., 2019 ). To help understand the processes that control the oxygen and carbon isotopic records from Sierra Agua Verde, the trends of δ 13 C carb and δ 18 O carb were reviewed between each observation, one by one, to identify those intervals where both records increase, decrease, or present opposite trends. A comparison with the paleobathymetry of the succession (Villanueva-Olea et al., 2019 ) was also incorporated into this review (Fig. 9 ). Evidence on microfacies and sedimentary facies is shown and discussed in depth in the work of Villanueva-Olea et al. ( 2019 ). Through the isotopic records are presented some stratigraphic intervals where δ 13 C carb and δ 18 O carb show a simultaneous increasing trend (Fig. 9 at 35.54–37.72, 75.59–77.33 and 95.95–98.23 m in the Visean, 114.91-120.05 m in the Serpukhovian, and 168.44-191.33, 204.29–206.30 and 216.14-223.28 m in the Bashkirian). This simultaneous behavior can be associated with a favored productivity and the presence of drier conditions. The increment of δ 13 C can be caused by the loss of the environmental 12 C due to the isotopic fractionation of photosynthesis (Porter et al., 2014 ; Schmid et al., 2018 ; Babalola et al., 2023 ). The increased δ 18 O can be triggered by processes like evaporation, interactions with deep water masses and/or a limited input of meteoric waters (Craig & Gordon, 1965 ; Hoefs, 2018 ; Horita & Wesolowski, 1994 ). The paleobathymetry by Villanueva-Olea et al. ( 2019 ) has helped to identify the processes that could have enhanced the increases in δ 18 O carb , whether the area was in deeper or shallower zones. For example, around the end of the Visean and the middle Serpukhovian sections, in Sierra Agua Verde are dominant shallower conditions of restricted and open lagoon, which coincides with a simultaneous increase in δ 13 C carb and δ 18 O carb records from that locality; it is possible that those periods have been characterized by an increase in productivity and an increased evaporation due to the shallow environments, and possibly a limited input of rainwater, allowing the increase in the isotopic records values (e.g., Babalola et al., 2023 ). Despite the previously discussed trends, it is possible to find stratigraphic intervals where δ 13 C carb and δ 18 O carb present decrements in values (Fig. 9 at 1.59–2.80, 5.89–8.14, 31.01–32.82 and 82.50-95.95 m in Visean, 101.50-114.91 and 120.05-123.29 m in Serpukhovian, 130.61-168.44, 191.33-204.29 and 206.30-216.14 m in Bashkirian, and 223.28-238.15 m in Moscovian). The simultaneous decreasing of carbon and oxygen isotopic records trends could be interpreted as a period of abundant inflows of meteoric waters (Al-Mojel et al., 2018 ; Herath et al., 2022 ; Keller et al., 2004 ; Marshall, 1992 ; Salih et al., 2019 ). This isotopic pattern, indicative of meteoric water influx, is prevalent in the Sierra Agua Verde records. This is congruent with the paleogeographic configurations of the region during Carboniferous, when Sierra Agua Verde sediments were mostly shallow and exposed to meteoric waters (Villanueva-Olea et al., 2019 ) and were located in a paleoequatorial zone where rainfalls were common and strong (Blakey, 2008 ). An opposite correlation between δ 13 C carb and δ 18 O carb may reflect different situations than those discussed above. Those stratigraphic intervals where δ 13 C carb values have an increment and those of δ 18 O carb decrease (Fig. 9 at 1.30–1.59, 32.82–33.69 and 81.04–82.50 m in Visean, 123.29-130.61 m in Serpukhovian, and 238.15-246.06 m in Moscovian) could be associated with high-productivity periods (Sass & Kolodny, 1972 ; Irwin et al., 1977 ; Geoffrey D. Thyne, James R. Boles, 1989). The decrements in δ 18 O values are generally associated with the input of rainwater (Al-Mojel et al., 2018 ; Herath et al., 2022 ; Keller et al., 2004 ; Marshall, 1992 ; Salih et al., 2019 ). In addition, the degradation of the produced organic matter release light oxygen in water that could contribute to the negative trend of the δ 18 O carb (Hudson, 1977 ; Irwin et al., 1977 ; Coleman, 1993 ; Mozley and Burns, 1993). These intervals of negative correlation, characterized by increasing δ 13 C carb and decreasing δ 18 O carb , may indicate periods of high productivity and increased rainfall in the Sierra Agua Verde region. Stratigraphic intervals where δ 13 C carb decreases and δ 18 O carb increases occur in La Joya Section (Fig. 9 at 1.30–1.59, 5.89–8.14, 31.01–32.82, 35.54–37.75, 75.59–77.33 and 81.04–82.50 m in Visean, 101.50-111.55 m in Serpukhovian, and 268.36–270.00 m in Moscovian). Periods of low productivity could be associated with low δ 13 C values (Hudson, 1977 ; Irwin et al., 1977 ; Coleman, 1993 ; Peter S. Mozley, Stephen J. Burns, 1993). However, upwellings could be playing an important role in equatorial coasts, enhancing productivity, and supplying 12 C (Liu et al., 2015 ; Tian et al., 2020 ). Organic matter degradation not only release 12 C, but also 16 O (Hudson, 1977 ; Irwin et al., 1977 ; Coleman, 1993 ; Peter S. Mozley, Stephen J. Burns, 1993). If the degradation of organic matter was sufficient to see the contribution of 12 C in the carbon isotopic records, it is feasible to think that 16 O could also have been significant to be reflected in a decreasing δ 18 O carb ; therefore, it is possible that other factors may have stimulated the increment of δ 18 O carb values. Shallow conditions could benefit the water evaporation and loss of 16 O, and deeper environments might facilitate interaction with deep water masses and reduce contact with meteoric waters. The evaporation due to warming is not congruent with the upwelling occurrence suggested for western Laurussia (Batt et al., 2007 ; Saltzman, 2003 ) and some equatorial Paleo-Tethyan localities (Buggisch et al., 2008 ; Grossman et al., 2008 ; Tian et al., 2020 ). An increase in local temperatures could have stratified the water column, preventing the upwelling occurrence (e.g., Grossman et al., 1993 ; H.-S. Mii et al., 2001 ; Batt et al., 2007 ). Thus, it is possible that the evaporation has occurred due to the establishment of drier conditions, where the input of meteoric waters was reduced, and the low relative humidity has led the escape of light water molecules (e.g., Wright & Vanstone, 2001 ; Haq & Schutter, 2008 ; Montañez & Poulsen, 2013 ). 2. Visean cluster In Fig. 5 it is possible to appreciate that most of the Visean isotopic data from La Joya groups are on the positive side of the δ 13 C carb axis. This happens because the δ 13 C carb record starts with relatively high values to follow a decreasing trend along the way (Fig. 4 ). Otherwise, the record of δ 18 O carb presents a positive trend along the Visean part of the record. As mentioned previously, periods with this contrary behavior can be associated with an increase in upwelling occurrence and evaporation (e.g., Coleman, 1993 ; Haq & Schutter, 2008 ; Montañez & Poulsen, 2013 ; Mozley & Burns, 1993). During the Mississippian, paleobotanical evidence suggests an increase in temperature and precipitations in equatorial regions (Raymond et al., 1989 ; Ross & Ross, 1985 ). These conditions led to the expansion of tropical forests and jungles (Algeo et al., 1995 ). The proliferation of vascular plants and root penetration increased soil weathering; in consequence, the nutrient flux enhanced in oceans and global marine productivity was favored (Algeo et al., 1995 ). The growth of the plants around the world led to the formation and expansion of carbon summits, creating, and increasing new reservoirs that sequestered 12 C from oceans and atmosphere (Berner, 1989 ). The global loss of 12 C is reflected in the Visean positive trend of the δ 13 C records from carbonate bulk from Europe (Buggisch et al., 2008 ) and brachiopods from Russia (Bruckschen & Veizer, 1997 ; Grossman et al., 2008 ; Korte et al., 2005 ; H.-S. Mii et al., 2001 ), with both record values oscillating between ~ + 1.5 and + 3.5‰ (Fig. 10 ). Instead, the bulk carbon isotopic record from Sierra Agua Verde presents a wider range of values (from ~ 0‰ to + 3.13‰) and a decreasing general trend along Visean section. Brachiopods δ 13 C record from West USA (Brand et al., 2012 ) and bulk carbonate δ 13 C records from South China (Buggisch et al., 2011 ; Liu et al., 2015 ) and West USA (Batt et al., 2007 ; Saltzman, 2003 ) also present the decreasing trend and intervals of values ~ from 0 to + 4‰ and ~ from − 1.9 to + 3.2‰ respectively (Fig. 10 ). The behavior of the variation of the upper part of these records is relatively similar to the Visean part of δ 13 C carb . The Visean part of δ 13 C carb may represent the upper part of Visean age. The differences in behavior and magnitude between Europe and Russia with West USA, South China and Sierra Agua Verde could be explained from a paleogeographic perspective. Villanueva-Olea et al. ( 2019 ) suggest that the differences between the isotopic records from La Joya and those from around the world could be caused by the formation of upwelling zones in Sierra Agua Verde. They propose that the upwelling zones have been formed by reorganizing the ocean circulation patterns reported in Western Laurussia (Liu et al., 2015 ). To robustly analyze this hypothesis, it is necessary to recognize the global oceanographic and climatological context of the Central Sonora region during the Carboniferous. During Visean, Southern China and Western USA were located in tropical regions while Russia and Europe were in higher latitudes (Blakey, 2008 ). Kelly et al. ( 1990 ) indicated an increment in the latitudinal gradient of temperatures along the world during this age. Contrasting the tropical conditions proposed for equatorial regions (Raymond, 1985 ; Raymond et al., 1989 ), some authors reported a rapid fall of the global sea level as a signal of the onset of Gondwana glaciation (e.g., Smith & Fred Read, 2000 ; Wright & Vanstone, 2001 ; Rygel et al., 2008 ). The decline in tropical foraminifer diversity (Kalvoda, 2002 ; Davydov et al., 2012 ) and the glacial deposits in Gondwana support the decrease in temperatures (Buggisch et al., 2008 ; Limarino et al., 2006 ). The latitudinal gradient of temperatures may have intensified trade winds and enhanced upwellings, as reported in western Laurussia (Batt et al., 2007 ; Saltzman, 2003 ) and some equatorial Paleo-Tethyan localities (Buggisch et al., 2008 ; Grossman et al., 2008 ; Tian et al., 2020 ). Even though the increased occurrence of upwellings in tropical paleoregions could have increased productivity in equatorial seaway locations (i.e., higher δ 13 C carb ), upwelling waters are known to present higher concentrations of nutrients and 12 C, due to the degradation of organic matter (Liu et al., 2015 ). The balance between productivity and upwellings could have influenced the differences in behavior and magnitude of δ 13 C records from different regions (Liu et al., 2015 ; Tian et al., 2020 ). The gradual intensification of upwellings in equatorial regions could have caused an isotopic disequilibrium, where the 12 C supplied by upwellings could have been higher than its usage for organic matter production. Thus, the δ 13 C values of some tropical seas may have been decreasing during the Visean age, as suggested by δ 13 C records from West USA (Mii et al., 1999 ; Saltzman & Thomas, 2012 ), South China (Liu et al., 2015 ) and Sierra Agua Verde. Some authors suggest that the inputs of riverine waters could diminish δ 13 C values on carbonate records (Marshall, 1992 ; Keller et al., 2004 ; Al-Mojel et al., 2018 ; Salih et al., 2019 ; Herath et al., 2022 ). The high concentration of 16 O in rainwater and river discharges, and the 12 C organic matter enriched riverine waters, simultaneously decrease the δ 13 C and δ 18 O values in sedimentary environments (Marshall, 1992 ; Keller et al., 2004 ; Al-Mojel et al., 2018 ; Salih et al., 2019 ; Herath et al., 2022 ). However, the δ 18 O carb trend is positive along the Visean part of the record. This probably suggests that the inputs of riverine waters did not contribute to the diminution of δ 13 C carb . This observation supports Villanueva-Olea et al. ( 2019 ). They indicate that the La Joya region may have been relatively far from continental uplifts. They support this idea with the lack of sufficient input of siliciclastic in the platform. In this way, it is feasible to consider that the La Joya region had very little interaction with riverine meteoric waters. Contrary to the behavior of δ 13 C carb from this study, the Visean part of the δ 18 O carb record presents an increasing trend. Villanueva-Olea et al. ( 2019 ) also report the increment in their Visean oxygen isotopic record from carbonate rocks. They argued that this behavior is explained by the global temperature decrement and the loss of global 16 O stored in polar ice sheets. However, this explanation applies to the δ 18 O carb of biogenic carbonates and fossil bioapatite (e.g., Mii et al., 1999 ; Mii et al., 2001 ; Batt et al., 2007 ). Several authors suggest that the positive trends in δ 18 O from carbonate rocks are mostly caused by the loss of local 16 O in processes like evaporation, interactions with deep water masses and a limited input of meteoric waters (e.g. Craig & Gordon, 1965 ; Horita & Wesolowski, 1994 ; Hoefs, 2018 ). According to Fig. 10 , during the Visean the isotopic signal can be explained by the presence of meteoric water. Similarly, the absence of the signal can be interpreted as periods of drought. This suggests that the interaction with meteoric waters may have been limited during the Visean. This is consistent with the hypothesis in several studies for the end of the Visean age, when an increase in seasonality coincided with a global tendency to drier conditions (Wright & Vanstone, 2001 ; Haq & Schutter, 2008 ; Montañez & Poulsen, 2013 ). Furthermore, Villanueva-Olea et al. ( 2019 ) reported that around the end of the Visean and the Middle Serpukhovian sections, in Sierra Agua Verde there were dominant shallower conditions of restricted and open lagoon. It is possible that those periods have been characterized by increased evaporation due to the shallow environments, and possibly a limited input of rainwater, allowing the increase in the oxygen isotopic record values (e.g., Babalola et al., 2023 ). Therefore, the δ 18 O carb record from the La Joya section supports the interpretation of a shift towards drier and more arid conditions in the Sierra Agua Verde region during the late Visean. 3. Serpukhovian-Bashkirian-Moscovian cluster Some studies based on sedimentary geochemistry suggest that the major continental glaciation on Gondwana began in late Visean and reached the first peak in the MBP (R. Chen & Sharma, 2016 ; Fielding & Frank, 2015 ; Montañez & Poulsen, 2013 ). The global cooling of the LPIA led to the loss of habitat diversity, which may have caused the mass biodiversity extinction in global marine ecosystems (McGhee et al., 2012 ; Stanley & Powell, 2003 ). This glacial event is recognized by the occurrence of various glacial deposits on Gondwana, a worldwide sea level fall, and a distinctive positive shift in δ 18 O records from conodont apatite and brachiopod calcite (H.-S. Mii et al., 2001 ; Buggisch et al., 2008 ; R. Chen & Sharma, 2016 ). In addition, a positive trend in carbonate δ 13 C records has been reported during MPB in different regions along Laurussia epicontinental seas (Popp et al., 1986 ; H. Mii et al., 1999 ; Grossman et al., 2008 ; Dyer et al., 2015 ). On the contrary, the δ 13 C carb record from Sierra Agua Verde presents a negative general trend with a particular variability. During the Serpukhovian, the δ 13 C carb record decreased until the early Bashkirian. Later, values exhibit a relatively abrupt increase (~ 2.31‰) to later decrease until reaching the lowest values (-2.6‰) of the whole record. Subsequently, the δ 13 C carb behavior turns into an increment trend during Upper Bashkirian that persists until the end of the record, during Moscovian. This behavior is similar to that presented in bulk δ 13 C records from Idaho and Nevada, reported by Batt et al. ( 2007 ) and Saltzman ( 2003 ) respectively (Fig. 10 ). Saltzman ( 2003 ) suggests that MBP δ 13 C carb records from Western North America are controlled mainly by nutrient availability and ocean productivity. Paleoatmospheric models suggest that the western tropical coasts of Laurussia were affected by strong wind fluxes that streamed from the Panthalassian high pressure system to the Intertropical Convergence Zone (Peyser & Poulsen, 2008 ). It is possible that the Sierra Agua Verde region has been affected by the same wind currents reported by Batt et al. ( 2007 ) and Saltzman ( 2003 ) for West USA. This climatological configuration could have produced variations in ocean productivity from the La Joya region, resulting in a δ 13 C carb record relatively similar to those from West USA. This is consistent with the conclusions of Stewart et al. ( 1999 ), who mention how the Sierra Agua Verde region represents inner-shelf deposits very similar to those outcrops in California and Nevada. The negative trend of δ 18 O carb could suggest the input of meteoric waters that bring 16 O into the Sierra Agua Verde paleoregion (e.g., Herath et al., 2022 ). This is consistent with the proposal of several authors, who mentioned that a gradual rise in temperatures and ice melting incremented global humidity and tropical precipitations during Pennsylvanian (Bishop et al., 2010 ; Gulbranson et al., 2010 ; Limarino et al., 2006 ; Davydov et al., 2012 ). In addition, the paleobathymetric reconstruction of Sierra Agua Verde presents a predominance of shallow environments (restricted lagoon and open circulation lagoon) during Serpukhovian, Bashkirian and Moscovian ages (Villanueva-Olea et al., 2019 ). These shallow conditions likely exposed the sediments to a greater influence from rainwater. Due to the Cerro Las Rastras isotopic records do not cover the Mississippian period, it is not possible to appreciate a decrease in the δ 18 O carb values that would allow identifying the signal of the interaction with meteoric waters. However, it is important to recall the similarity found between the δ 18 O carb values of Cerro Las Rastras and the upper range of values from Sierra Agua Verde (Fig. 5 ). This could suggest that the meteoric waters signal in the δ 18 O carb record is not strong enough to affect deeper waters far from the coastline (e.g. Craig & Gordon, 1965 ; Hoefs, 2018 ; Horita & Wesolowski, 1994 ). More studies that involve the deep-water Mississippian and Pennsylvanian rocks in Central Sonora are necessary to corroborate this hypothesis. CONCLUSIONS The congruence between Western US and Sierra Agua Verde δ¹³C carb records, and the similarity between central Sonora isotopic data, supports that the results obtained in this study have no significant diagenetic imprint and are good proxies to make consistent interpretations during the Mid-Carboniferous interval of the LPIA. The Carboniferous isotopic records from Central Sonora are similar to those from the West USA and South China but are different from those from Russia and Europe. These similarities and differences can be attributed to the Carboniferous position of these regions where Sonora, West USA and South China were located in equatorial regions, while Russia and Europe, in higher latitudes. In this way, the latitudinal differences result in different local processes that would modify the involved isotopic imprints. The relationship between central Sonora and West USA δ 18 O carb and δ 13 C carb records suggest that the same processes controlled the Mississippian isotopic signals of these regions. It is possible that the δ 13 C carb records of these regions were strongly ruled by upwellings and productivity while δ 18 O carb was greatly controlled by the input of meteoric waters. The decrement trend of δ 13 C carb and the gradual increment in δ 18 O carb of the Visean section from Sierra Agua Verde records are consistent with the climate change reported for the age. The decrease in temperature, the increment in seasonality and latitudinal temperature gradient triggered the intensification of local upwellings and the limitation of rainfall in the region. On the other hand, the negative trend of δ 18 O carb in La Joya records, presented in Serpukhovian, Bashkirian and Moscovian ages, could be suggesting the influence of meteoric waters that could have been apporting 16 O into central Sonora region. The decreasing trend of δ 13 C carb presents a similar variability to that occurring in bulk δ 13 C carb records from Idaho and Nevada. It is possible that Sierra Agua Verde and West USA have been affected by the same wind currents which produced similar variations in ocean productivity. On the other hand, samples of the southwestern sector of Cerro Las Rastras confirm the Pennsylvanian age; however, the conodont association seem to suggest that different sample points may be younger (Desmoinesian - Virgilian; Middle - Late Pennsylvanian), and one sample even older (latest Devonian-earliest Mississippian; 22LR-10; Table 1 ; Fig. 6 ). The discrepancies presented by Villanueva-Olea et al. ( 2019 ) seem to be congruent with the background of Carboniferous Western Laurussian coasts. The interactions with meteoric waters and upwellings could have had a strong influence in Sierra Agua Verde δ 13 C and δ 18 O carbonate records during Mid-Carboniferous period. Due to the Carboniferous paleoequatorial position of Sierra Agua Verde, covered by tropical waters and far from polar regions, the joint study of δ 13 C carb and δ 18 O carb in limestones can help to understand the relationship between global and local environmental processes that affect the isotopic imprints on carbonated rocks. The strong relationship between early diagenesis and local environmental conditions could support the reconstruction of paleoceanographic and paleoclimatic conditions of Sierra Agua Verde paleoregion. Considering early diagenesis when interpreting δ 13 C and δ 18 O values can lead to a revised understanding of carbon and oxygen isotopic records. This study offers an approximation of how the environmental conditions were during the MPB in Sierra Agua Verde and how they were related to global climatology. Sonora outcrops have a great potential for Paleozoic geochemical studies and more investigation must be done in the region. Declarations The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Pilar Navas-Parejo reports financial support was provided by PAPIIT-DGAPA-UNAM. Salvador Gutierrez Reyes reports financial support was provided by CONAHCyT. Pilar Navas-Parejo reports financial support was provided by CONAHCyT. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ACKNOWLEDGEMENTS The data involved in this work was obtained during the research work of SGR for his PhD thesis. In this way, we thank the Consejo Nacional de Humanidades, Ciencia y Tecnología (CONAHCyT) for the postgraduate scholarship. We also thank the Posgrado en Ciencias de la Tierra, and the Estación Regional del Noroeste, UNAM, for their support. We thank Francisco Otero, from the Laboratorio de Isótopos Estables (LANGEM, UNAM), and Korynthia Lopez, from the Laboratorio de Análisis de Isótopos Estables (PCTY, UNAM), for the support in stable isotopic analysis. This work was supported by the CONAHCyT [grant numbers CF-7351]; and the UNAM [grant number UNAM-DGAPA-PAPIIT IN114923]. Finally, we want to give very special thanks to Fernando Núñez Useche for his great assistance with this work. His contributions in the interpretation of δ¹³C and δ 18 O in limestones were essential to reconstruct the paleoenvironmental conditions concluded in this work. AUTHOR CONTRIBUTIONS Authors: Salvador Gutiérrez Reyes https://orcid.org/0009-0008-9860-7885 Juan Moisés Casas Peña https://orcid.org/0000-0003-3751-3945 Rafael Villanueva Olea https://orcid.org/0000-0002-8051-3150 Pilar Navas-Parejo https://orcid.org/0000-0002-1464-948X Conceptualization Salvador Gutiérrez Reyes Pilar Navas-Parejo Data curation Salvador Gutiérrez Reyes Formal análisis Salvador Gutiérrez Reyes Juan Moisés Casas Peña Rafael Villanueva Olea Pilar Navas-Parejo Funding acquisition Pilar Navas-Parejo Investigation Salvador Gutiérrez Reyes Juan Moisés Casas Peña Rafael Villanueva Olea Pilar Navas-Parejo Methodology Salvador Gutiérrez Reyes Juan Moisés Casas Peña Rafael Villanueva Olea Project administration Salvador Gutiérrez Reyes Pilar Navas-Parejo Resources Salvador Gutiérrez Reyes Pilar Navas-Parejo Software Salvador Gutiérrez Reyes Supervision Pilar Navas-Parejo Validation Salvador Gutiérrez Reyes Juan Moisés Casas Peña Rafael Villanueva Olea Pilar Navas-Parejo Visualization Salvador Gutiérrez Reyes Juan Moisés Casas Peña Rafael Villanueva Olea Pilar Navas-Parejo Writing – original draft Salvador Gutiérrez Reyes Writing – review and editing Juan Moisés Casas Peña Rafael Villanueva Olea Pilar Navas-Parejo References Algeo, T. 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Glacio-eustasy and δ13C across the Mississippian–Pennsylvanian boundary in the eastern Paleo-Tethys Ocean (South China): Implications for mid-Carboniferous major glaciation. Geological Journal , 55 (4), 2704–2716. https://doi.org/10.1002/gj.3551 Villanueva Olea, R. (2019). Microfósiles como indicadores de cambios paleoambientales en el carbonífero del estado de Sonora (Sierras Agua Verde y Mesteñas) . UNAM. Villanueva-Olea, R., Barragán, R., Palafox-Reyes, J. J., Jiménez-López, J. C., & Buitrón-Sánchez, B. E. (2019). Microfacies and stable isotope analyses from the Carboniferous of the La Joya section in Sierra Agua Verde, Sonora, Mexico. Boletin de La Sociedad Geologica Mexicana , 71 (3), 585–607. https://doi.org/10.18268/BSGM2019v71n3a1 Villanueva-Olea, R., Buitrón-Sánchez, B. E., Palafox-Reyes, J. J., & Piña-Flores, S. (2016). Crinoides (Echinodermata: Crinoidea) del Pensilvánico de sierra Las Mesteñas, NE de Sonora, México. Revista Mexicana de Biodiversidad , 87 (4), 1225–1234. https://doi.org/10.1016/j.rmb.2016.10.014 Wright, V. P., & Vanstone, S. D. (2001). Onset of Late Palaeozoic glacio-eustasy and the evolving climates of low latitude areas: a synthesis of current understanding. Journal of the Geological Society , 158 (4), 579–582. https://doi.org/10.1144/jgs.158.4.579 Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {\"props\":{\"pageProps\":{\"initialData\":{\"identity\":\"rs-6165627\",\"acceptedTermsAndConditions\":true,\"allowDirectSubmit\":true,\"archivedVersions\":[],\"articleType\":\"Research Article\",\"associatedPublications\":[],\"authors\":[{\"id\":456925988,\"identity\":\"f040d50b-95aa-42d5-804f-b75b4f5ea25f\",\"order_by\":0,\"name\":\"Salvador Gutiérrez Reyes\",\"email\":\"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAklEQVRIiWNgGAWjYFAC5gYGBjY4zwaIGRsP4NfCCNPCDCLSwCIkaTkMFsOrRb79YJvEjzKbfAb+9Yc/V1Sct1vbfhhoS41NNC4tBmcS2yR7zqVZNkg8ZjA8c+Z28rYziUAtx9JyG3BpYUhsNuBtO2zAIHGYIbGx7Xay2QGgFsaGwzi1yPc/bDb8C9VysPHfuWSz8w/xa2G4kdj4GGwLfzNjY2PDATuzGwRsMbjxsPGxzLk0AzYJZmPGhmPJCWY3gLYk4PGLfH/ygYNvymwM+PkPPv7YUGNnb3Y+/eGDDzU2uB0GA2wSCWA6EawygZByMOA/AKbsiVI8CkbBKBgFIwoAACQGZEX/S51SAAAAAElFTkSuQmCC\",\"orcid\":\"https://orcid.org/0009-0008-9860-7885\",\"institution\":\"Universidad Nacional Autonoma de Mexico Instituto de Geologia\",\"correspondingAuthor\":true,\"prefix\":\"\",\"firstName\":\"Salvador\",\"middleName\":\"Gutiérrez\",\"lastName\":\"Reyes\",\"suffix\":\"\"},{\"id\":456925989,\"identity\":\"05a4df2c-6de8-481a-88a0-9d19589b68b3\",\"order_by\":1,\"name\":\"Juan Moisés Casas Peña\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Universidad Nacional Autónoma de México: Universidad Nacional Autonoma de Mexico\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Juan\",\"middleName\":\"Moisés Casas\",\"lastName\":\"Peña\",\"suffix\":\"\"},{\"id\":456925990,\"identity\":\"4e8ad9d1-6f53-46b7-8b07-ef64fb414e9c\",\"order_by\":2,\"name\":\"Rafael Villanueva Olea\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Universidad Nacional Autónoma de México: Universidad Nacional Autonoma de Mexico\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Rafael\",\"middleName\":\"Villanueva\",\"lastName\":\"Olea\",\"suffix\":\"\"},{\"id\":456925991,\"identity\":\"eb5b9707-3bf6-4e6d-a166-3895ac15864a\",\"order_by\":3,\"name\":\"Pilar Navas-\",\"email\":\"\",\"orcid\":\"\",\"institution\":\"Universidad Nacional Autónoma de México: Universidad Nacional Autonoma de Mexico\",\"correspondingAuthor\":false,\"prefix\":\"\",\"firstName\":\"Pilar\",\"middleName\":\"\",\"lastName\":\"Navas-\",\"suffix\":\"\"}],\"badges\":[],\"createdAt\":\"2025-03-05 21:53:38\",\"currentVersionCode\":1,\"declarations\":\"\",\"doi\":\"10.21203/rs.3.rs-6165627/v1\",\"doiUrl\":\"https://doi.org/10.21203/rs.3.rs-6165627/v1\",\"draftVersion\":[],\"editorialEvents\":[],\"editorialNote\":\"\",\"failedWorkflow\":false,\"files\":[{\"id\":83028171,\"identity\":\"4d2a6f43-695d-4b15-9b5a-bba7f8d33e5e\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:44:11\",\"extension\":\"jpeg\",\"order_by\":1,\"title\":\"Figure 1\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":204024,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003ePaleozoic outcrops in Sonora State, northwestern Mexico, with location of the studied sections. Modified from Navas-Parejo et al. (2017). The study area of Batt et al. (2007) is also indicated on the map due to its relevance to our research.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage1.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/db4b064c3e59933d5300a3c9.jpeg\"},{\"id\":83030304,\"identity\":\"cffd013d-e719-4aa3-b081-613d054104fb\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 09:00:11\",\"extension\":\"jpeg\",\"order_by\":2,\"title\":\"Figure 2\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":237918,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eStratigraphic column of Sierra Agua Verde, Sonora, NW Mexico. Modified from Navas-Parejo et al. (2017)and Villanueva-Olea et al. (2019).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage2.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/1d95c1ab4034322b4ace72af.jpeg\"},{\"id\":83028186,\"identity\":\"70e19008-fba9-4a25-97d1-134b06bc21c8\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:44:11\",\"extension\":\"jpeg\",\"order_by\":3,\"title\":\"Figure 3\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":518163,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eSimplified geological map of the Barita de Sonora area showing the samples location for this study. Map modified from Poole et al. (2008).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage3.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/b2f274020aa67c54d351d9f1.jpeg\"},{\"id\":83029087,\"identity\":\"274fa173-a0f3-47bd-a138-b9ac1c6a956b\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:52:11\",\"extension\":\"jpeg\",\"order_by\":4,\"title\":\"Figure 4\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":114513,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eEstimation of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) (A) and the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) (B) from Sierra Agua Verde limestones. The geological stages are approximations from conodont associations in Navas-Parejo et al. (2017).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage4.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/c33ddcd08ebc92502abfce91.jpeg\"},{\"id\":83029082,\"identity\":\"fadb00f0-dde6-4233-be4a-246aa6dc0650\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:52:11\",\"extension\":\"jpeg\",\"order_by\":5,\"title\":\"Figure 5\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":92905,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eScatter cross-plot of δ¹³C and δ\\u003csup\\u003e18\\u003c/sup\\u003eO Carboniferous records from La Joya and Cerro Las Rastras carbonate rocks. Besides, brachiopods from West USA (Data from Grossman et al., 1991, 1993, 2008; Mii et al., 1999; Stanton et al., 2002; Korte et al., 2005; Mazzullo et al., 2007; Brand et al., 2012;) and Russia (Data from Bruckschen et al., 1999, 2001; Mii et al., 2001; Korte et al., 2005; Grossman et al., 2008) are also presented.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage5.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/13aa0c014f1842e9cfcb9e96.jpeg\"},{\"id\":83028177,\"identity\":\"c72997a1-3131-461e-8c12-34f6d67922da\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:44:11\",\"extension\":\"jpeg\",\"order_by\":6,\"title\":\"Figure 6\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":677375,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eP1 elements of \\u003cem\\u003eIdiognathodus, Gondolella, Idiognathoides\\u003c/em\\u003e, and \\u003cem\\u003eStreptognathodus\\u003c/em\\u003e, from the Middle to Late Pennsylvanian (Desmoinesian to Virgilian?) of Rancho Nuevo Formation in the Sonora Allochthon as well as \\u003cem\\u003eNeopolygnathus\\u003c/em\\u003e from the latest Devonian - Early Mississippian of Sierra Martínez Group (central Sonora); scale bars are equivalent to 200 µm. \\u003cstrong\\u003e(1-8)\\u003c/strong\\u003e \\u003cem\\u003eIdiognathodus \\u003c/em\\u003esp. oral views, sample specimens (1) 22LR1-ac-10b, (2) 22LR2-for-4b, (3) 22LR2-for-5b, (4) 22LR4-for-2a; (5) 22LR8-ac-1a; (6)22LR11-ac-1a, (7) 22LR15-ac-1b; (8) 22LR1-ac-13a; \\u003cstrong\\u003e(9-10, 11-12, 17-8, 21)\\u003c/strong\\u003e \\u003cem\\u003eGondolella \\u003c/em\\u003esp. oral and aboral views\\u003cem\\u003e, \\u003c/em\\u003esample specimens (9-10) 22LR1-ac-14b, (11-12) 22LR2-ac-2b, (17-18) 22LR4-for-5c; (21) 22LR11-ac-2a; \\u003cstrong\\u003e(13)\\u003c/strong\\u003e \\u003cem\\u003eIdiognathoides \\u003c/em\\u003esp.\\u003cem\\u003e \\u003c/em\\u003eoral view, sample specimen 22LR4-for-8b; \\u003cstrong\\u003e(14-16)\\u003c/strong\\u003e \\u003cem\\u003eStreptognathodus \\u003c/em\\u003esp. oral views, sample specimens (14)22LR4-for-9c, (15) 22LR4-for-7b, (16) 22LR7-for-1c; \\u003cstrong\\u003e(19-20)\\u003c/strong\\u003e \\u003cem\\u003eNeopolygnathus \\u003c/em\\u003esp. oral and aboral views, sample specimen 22LR10-for-2c.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage6.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/fcda81cb67a3e08ea38467bb.jpeg\"},{\"id\":83028175,\"identity\":\"451f1c6b-71cd-4e96-8ce2-0cc008582cdc\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:44:11\",\"extension\":\"jpeg\",\"order_by\":7,\"title\":\"Figure 7\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":133260,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eIsotope ratios in Sierra Agua Verde samples along the stratigraphic column. Dark lines show δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) (A) and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) (B) from this study. Gray lines show δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) (A) and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) (B) of Villanueva-Olea et al. (2019). The geological stages are approximations from conodont associations in Navas-Parejo et al. (2017).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage7.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/86ff803be5dc8b2fba21bda0.jpeg\"},{\"id\":83030305,\"identity\":\"ee8825ba-3007-4625-a8fc-da930fb2ee14\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 09:00:11\",\"extension\":\"jpeg\",\"order_by\":8,\"title\":\"Figure 8\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":309004,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(A) δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) and (B) δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) from Sierra Agua Verde limestones. (C) δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) and (D) δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (‰ VPDB) from West USA limestones and biogenic components (Batt et al., 2007). The geological stages in (A) and (B) are approximations from conodont associations in Navas-Parejo et al. (2017). The geological stages in (c) and (D) are based on biostratigraphic zonations developed by Abplanalp et al. (2009) and calibrated to the Gradstein et al., (2004) timescale.\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage8.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/56d4de52fba26f339c563972.jpeg\"},{\"id\":83029085,\"identity\":\"23afb30b-a8e9-4cc0-95d7-96c51430728d\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:52:11\",\"extension\":\"jpeg\",\"order_by\":9,\"title\":\"Figure 9\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":191837,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003e(A) Environmental processes that might have been affecting the variability of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e records. (B) Reconstruction of Sierra Agua Verde paleobathymetry from facies associations (Villanueva-Olea et al., 2019). (C) δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e (VPDB) (‰) record from this study. (D) Estimated δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (VPDB) (‰) data from this work. The geological stages are approximations from conodont associations in Navas-Parejo et al. (2017).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage9.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/432fb1b18ab928025f162f35.jpeg\"},{\"id\":83029084,\"identity\":\"ecda0d51-cf5a-4257-9731-d9c3c331e828\",\"added_by\":\"auto\",\"created_at\":\"2025-05-19 08:52:11\",\"extension\":\"jpeg\",\"order_by\":10,\"title\":\"Figure 10\",\"display\":\"\",\"copyAsset\":false,\"role\":\"figure\",\"size\":202796,\"visible\":true,\"origin\":\"\",\"legend\":\"\\u003cp\\u003eIsotopic records of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003eVPDB\\u003c/sub\\u003e (‰) from Laurentia. (A) shows the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003eVPDB\\u003c/sub\\u003e (‰) estimated in bulk carbonated rocks from Europe (Data from Buggisch et al., 2008) and brachiopods from Russia (Data from Bruckschen et al., 1999, 2001; Mii et al., 2001; Korte et al., 2005; Grossman et al., 2008). (B) present δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003eVPDB\\u003c/sub\\u003e (‰) analyzed in brachiopods from West USA (Data from Grossman et al., 1991, 1993, 2008; Mii et al., 1999; Stanton et al., 2002; Korte et al., 2005; Mazzullo et al., 2007; Brand et al., 2012) and Bulk carbonated rocks from South China (Data from Buggisch et al., 2011; Liu et al., 2015; Qie et al., 2016) and West USA (Data from Saltzman, 2003; Batt et al., 2007).\\u003c/p\\u003e\",\"description\":\"\",\"filename\":\"floatimage10.jpeg\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/317891583fb838dd4a4d12c8.jpeg\"},{\"id\":85760467,\"identity\":\"83fbc49a-19c1-4e58-b2e5-5233c7df61a4\",\"added_by\":\"auto\",\"created_at\":\"2025-07-01 11:29:33\",\"extension\":\"pdf\",\"order_by\":0,\"title\":\"\",\"display\":\"\",\"copyAsset\":false,\"role\":\"manuscript-pdf\",\"size\":4011915,\"visible\":true,\"origin\":\"\",\"legend\":\"\",\"description\":\"\",\"filename\":\"manuscript.pdf\",\"url\":\"https://assets-eu.researchsquare.com/files/rs-6165627/v1/81f5e742-74d1-4b74-af68-e476def627d3.pdf\"}],\"financialInterests\":\"\",\"formattedTitle\":\"The carbonate-derived δ¹³C and δ¹⁸O records as proxies for Mid-Carboniferous climate in northwestern Mexico\",\"fulltext\":[{\"header\":\"INTRODUCTION\",\"content\":\"\\u003cp\\u003eThe Carboniferous is a geological period marked by significant environmental variations (Aretz et al., \\u003cspan citationid=\\\"CR4\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e; Chen et al., \\u003cspan citationid=\\\"CR21\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e). Continental drift closed the communication between Paleotethys and Rheic Ocean during the Mississippian-Pennsylvanian Boundary (MPB) (Davydov \\u0026amp; C\\u0026oacute;zar, \\u003cspan citationid=\\\"CR27\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e), which eventually led to the Pangea supercontinent formation (Rogers \\u0026amp; Santosh, \\u003cspan citationid=\\\"CR86\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e), a global tectonic event that culminated by the end of the Permian.\\u003c/p\\u003e \\u003cp\\u003eDuring the MPB, the approach of Laurussia and Gondwana caused changes on equatorial ocean currents, transporting more heat to polar regions (Qiao \\u0026amp; Shen, 2014; Conde et al., 2024). The movement of Gondwana around the south pole produced variations on ice covering (Caputo \\u0026amp; Crowell, \\u003cspan citationid=\\\"CR20\\\" class=\\\"CitationRef\\\"\\u003e1985\\u003c/span\\u003e). The proliferation of terrestrial plants, the extension of organic carbon storages as coal, and the increase in continental weathering induced a fall in atmospheric CO\\u003csub\\u003e2\\u003c/sub\\u003e and a global cooling trend (Ronov, \\u003cspan citationid=\\\"CR87\\\" class=\\\"CitationRef\\\"\\u003e1982\\u003c/span\\u003e; Algeo et al., \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1995\\u003c/span\\u003e; Chen \\u0026amp; Sharma, \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e; Chen et al., \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Tian et al., \\u003cspan citationid=\\\"CR103\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). This gave rise to the Late Paleozoic Ice Age (LPIA), one of the most severe glaciations of the Phanerozoic (Crowley, \\u003cspan citationid=\\\"CR26\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e). The LPIA event is associated with 3 glacial pulses during the Carboniferous period (Isbell et al., \\u003cspan citationid=\\\"CR48\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e). The first glacial pulse occurred during the Frasnian, potentially extending into the Tournaisian. The second glacial pulse spanned the Serpukhovian and Bashkirian stages. Finally, the third pulse began in the Kasimovian and persisted until the late Sakmarian. Changes in paleoceanography, biogeochemical carbon cycling and global temperature associated with these pulses are preserved in carbon and oxygen isotopic compositions of marine carbonates and fossils. Although diagenetic processes can modify the isotopic records of δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO in carbonate rocks (Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Swart \\u0026amp; Eberli, \\u003cspan citationid=\\\"CR102\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; H\\u0026ouml;nig \\u0026amp; John, \\u003cspan citationid=\\\"CR44\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e), a joint study of these proxies is an effective tool for evaluating and understanding the past environmental condition changes as well as diagenetic effects.\\u003c/p\\u003e \\u003cp\\u003eThe simultaneous evaluation of δ\\u0026sup1;\\u0026sup3;C and δ\\u003csup\\u003e18\\u003c/sup\\u003eO variations in limestones from localities far from polar regions helps to understand the relationship between global and local environmental processes that affect the isotopic signatures on carbonate rocks. Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) were the first to analyze the carbon and oxygen isotope ratios (δ\\u0026sup1;\\u0026sup3;C and δ\\u0026sup1;⁸O) in carbonate rocks from the La Joya section of the Sierra Agua Verde mountain range in Sonora, northwestern Mexico. The authors concluded that their isotopic records were partially congruent with the global MPB climate conditions proposed by other studies (Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e; Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). They also indicated that some discrepancies are due to the input \\u003csup\\u003e16\\u003c/sup\\u003eO enriched freshwater and \\u003csup\\u003e12\\u003c/sup\\u003eC by regional upwellings as causal factors. This study builds upon previous isotopic investigations by analyzing the carbon and oxygen isotope ratios (δ\\u0026sup1;\\u0026sup3;C and δ\\u0026sup1;⁸O) in carbonate rocks from central Sonora. We critically re-interpret the isotopic sequences reported by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) for the La Joya section, considering the influence of diagenesis and local environmental variations. This study also presents new carbon and oxygen isotopic data from the Rancho Nuevo Formation in the southwestern sector of Cerro Las Rastras, east of Mina de Barita in central Sonora. Samples were collected primarily from this formation, and the analysis includes a conodont biostratigraphic overview.\\u003c/p\\u003e\"},{\"header\":\"GEOLOGICAL SETTING\",\"content\":\"\\u003cp\\u003eMexico possesses a stratigraphic record of Carboniferous rocks. These rocks are relatively abundant and better preserved in the northwestern region of the country (e.g., Navas-Parejo, \\u003cspan citationid=\\\"CR65\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e and references therein). During the Carboniferous period, most of the current State of Sonora was located much closer to the equator than it is today (Peyser \\u0026amp; Poulsen, \\u003cspan citationid=\\\"CR71\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). As a result, the region was submerged under tropical waters, which led to the deposition of Carboniferous calcareous rocks (Gutschick \\u0026amp; Sandberg, \\u003cspan citationid=\\\"CR39\\\" class=\\\"CitationRef\\\"\\u003e1983\\u003c/span\\u003e; Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e). The late Paleozoic fossils of Sonora are abundant and mainly constituted of fusulinids, foraminifers, corals, brachiopods and less common algae, radiolarians, bryozoans, and crinoids (Buitr\\u0026oacute;n-S\\u0026aacute;nchez et al., \\u003cspan citationid=\\\"CR19\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Stevens et al., \\u003cspan citationid=\\\"CR99\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e, among many others). Marine vertebrates are mostly represented by conodonts and some remains of chondrichthyans (e.g., Navas-Parejo et al., \\u003cspan citationid=\\\"CR67\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e; Mart\\u0026iacute;nez-P\\u0026eacute;rez et al., \\u003cspan citationid=\\\"CR60\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e; Lara-Pe\\u0026ntilde;a et al., \\u003cspan citationid=\\\"CR55\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR56\\\" class=\\\"CitationRef\\\"\\u003e2021\\u003c/span\\u003e, among others). Facies from two distinct marine environments characterize the region, such as: (1) shallow marine deposits, accumulated on shallow cratonic seas and continental margin platforms, which are exposed in the northern and central portions of the state (Stewart and Poole, \\u003cspan citationid=\\\"CR72\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e); and (2) the deep ocean sediments, that are grouped in the Sonora Allochthon, which mainly crops out in the central region of the state (Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eOne of the most studied areas of Sonoran Paleozoic is Sierra Agua Verde, the first study area herein. This mountain range is located in the central area of the state (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). It is composed of sedimentary, igneous, and metamorphic rocks of Paleozoic, Mesozoic, and Cenozoic ages. Building upon the initial work of Poole et al. (\\u003cspan citationid=\\\"CR80\\\" class=\\\"CitationRef\\\"\\u003e1984\\u003c/span\\u003e), the most exhaustive geological work in Sierra Agua Verde was made by Stewart et al. (\\u003cspan citationid=\\\"CR100\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e), who studied the Neoproterozoic (?)-Pennsylvanian interval of the succession. Their integrative work included the definition of several map units based on lithostratigraphy but mostly on biostratigraphy by means of conodonts, foraminifera, algae, corals and \\u003cem\\u003eincertae sedis\\u003c/em\\u003e, concluding that Sierra Agua Verde Paleozoic succession represents an inner-shelf depositional environment.\\u003c/p\\u003e \\u003cp\\u003eConodont analysis of the La Joya section in the Sierra Agua Verde indicates the Laurussian carbonate shelf reached this region during the Late Paleozoic (Navas-Parejo et al., \\u003cspan citationid=\\\"CR67\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e). Isotopic studies by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) indicate that Sierra Agua Verde experienced unique paleoenvironmental conditions during the MPB. Their analysis of oxygen and carbon isotopes (δ\\u003csup\\u003e18\\u003c/sup\\u003eO and δ\\u003csup\\u003e13\\u003c/sup\\u003eC) from the section deviated from global MPB trends, such as the oxygen isotope excursion linked to polar ice sheet melting and the carbon isotope excursion at the beginning of the Pennsylvanian (Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e \\u0026amp; \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Joachimski et al., \\u003cspan citationid=\\\"CR50\\\" class=\\\"CitationRef\\\"\\u003e2006\\u003c/span\\u003e). Instead, both δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO showed a decreasing trend, likely caused by freshwater input (rich in \\u003csup\\u003e16\\u003c/sup\\u003eO) and regional upwellings (rich in \\u003csup\\u003e12\\u003c/sup\\u003eC). This suggests that Sierra Agua Verde experienced distinct conditions compared to global patterns during the MPB, likely influenced by local factors like freshwater influx and upwelling.\\u003c/p\\u003e \\u003cp\\u003eThe type locality of the Sonora Allochthon crops out in the central region of Sonora (Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Navas-Parejo, \\u003cspan citationid=\\\"CR65\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e), known as the Barita de Sonora. The second study area herein, Cerro Las Rastras, is located within this Sonora Allochthon type locality, specifically within the Barita de Sonora area (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e). The Barita de Sonora area contains fossils that indicate a wide range of ages. Regarding the Carboniferous, Early Mississippian conodonts have been documented (Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e), within the Barita de Sonora area, suggesting a late Visean to Bashkirian age. Other studies using radiolarians and foraminifera indicate the presence of Late Mississippian and possibly Early Pennsylvanian ages (Poole et al., \\u003cspan citationid=\\\"CR75\\\" class=\\\"CitationRef\\\"\\u003e1983\\u003c/span\\u003e; Bartolini, \\u003cspan citationid=\\\"CR7\\\" class=\\\"CitationRef\\\"\\u003e1988\\u003c/span\\u003e; Bartolini et al., \\u003cspan citationid=\\\"CR8\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e). Poole \\u0026amp; Amaya-Mart\\u0026iacute;nez (\\u003cspan citationid=\\\"CR72\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e) found fusulinids, radiolarians, and conodonts representing all Pennsylvanian stages in the Rancho Nuevo Formation. Stevens et al., (\\u003cspan citationid=\\\"CR99\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e) reported fusulinids from Desmoinesian to Virgilian in Rancho Nuevo Formation (middle Moscovian to Gzhelian).\\u003c/p\\u003e \\u003cp\\u003eThe Sonora Allochthon was affected by a deformation system developed with the approach and convergence of Laurrusia and Gondwana. This deformation began during the Mississippian period, resulting in the folding and thrusting of the rocks in the region (Poole \\u0026amp; Perry, \\u003cspan citationid=\\\"CR76\\\" class=\\\"CitationRef\\\"\\u003e1997\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR77\\\" class=\\\"CitationRef\\\"\\u003e1998\\u003c/span\\u003e). The deformation also involved a displacement of deep-marine successions, around ~\\u0026thinsp;100\\u0026ndash;200 km northward, which resulted in overlying the Carboniferous-Permian carbonate shelf (Poole \\u0026amp; Amaya-Mart\\u0026iacute;nez, \\u003cspan citationid=\\\"CR72\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e). Currently, the vestiges of this deformational event are interpreted as the western sector of the Ouachita-Marathon-Sonora Orogenic Belt (Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\"},{\"header\":\"MATERIALS AND METHODS\",\"content\":\"\\u003cp\\u003e1. \\u003cb\\u003eStudied section\\u003c/b\\u003e\\u003c/p\\u003e\\n\\u003ch3\\u003e1. La Joya section\\u003c/h3\\u003e\\n\\u003cp\\u003eLa Joya section is located 30 km north of the Sonora Allochthon and constitutes one of the southernmost outcrops of the continental shelf of Laurussia (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e). The stratigraphic section studied was previously described by Navas-Parejo et al. (\\u003cspan citationid=\\\"CR67\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e) and Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). This is a 270 m-thick succession that crops out between La Joya and El Palmar streams (base: 29\\u0026deg; 14' 29\\\" N, 109 \\u0026deg; 51' 25\\\" W, top: 29\\u0026deg; 14' 25\\\" N, 109\\u0026deg; 51' 3\\\" W). Despite partial vegetation cover, the outcrop exposes a well-preserved stratigraphic carbonate succession (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig2\\\" class=\\\"InternalRef\\\"\\u003e2\\u003c/span\\u003e). It includes beds of limestone, fine-grained sandy limestone with chert and sandstone. A detailed description of the section can be found in Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eThe biostratigraphy of the La Joya section of Sierra Agua Verde was based on the detailed study of conodonts of Navas-Parejo et al. (\\u003cspan citationid=\\\"CR67\\\" class=\\\"CitationRef\\\"\\u003e2017\\u003c/span\\u003e). In the lower part of the section occurs a conodont association that characterizes the Meramecian (Visean) \\u003cem\\u003ehomopunctatus-Upper texanus\\u003c/em\\u003e Zones in the western United States conodont zonation (Poole \\u0026amp; Sandberg, \\u003cspan citationid=\\\"CR79\\\" class=\\\"CitationRef\\\"\\u003e1991\\u003c/span\\u003e). In level LJ26, at 81.04 m, the appearance of a distinct conodont association marks the lower boundary of the Meramecian \\u003cem\\u003eCavusgnathus\\u003c/em\\u003e Zone (Poole \\u0026amp; Sandberg, \\u003cspan citationid=\\\"CR79\\\" class=\\\"CitationRef\\\"\\u003e1991\\u003c/span\\u003e). The last occurrence of \\u003cem\\u003eCavusgnathus unicornis\\u003c/em\\u003e morphotype β allowed the recognition of the Meramecian-Chesterian boundary at level LJ34 (101.05 m). The \\u003cem\\u003enaviculus\\u003c/em\\u003e and \\u003cem\\u003eunicornis\\u003c/em\\u003e Mississippian Zones were not identified due to the absence of the nominative species. However, the only occurrence of \\u003cem\\u003eRhachistognathus\\u003c/em\\u003e species in the La Joya section, in sample LJ38 (120.05 m), helped to identify the last two conodont biozones of the uppermost part of the Mississippian. At sample LJ40 (130.61 m), the first occurrence of the \\u003cem\\u003eDeclinognathodus noduliferus\\u003c/em\\u003e group species indicates the base of the Pennsylvanian. Villanueva Olea et al. (2019) marked the possible location of the Morrowan-Atokan boundary (aprox. Bashkirian-Moscovian boundary) at level LJ57 (223.28 m).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003e2. SW sector of Cerro Las Rastras\\u003c/h3\\u003e\\n\\u003cp\\u003eCerro Las Rastras is a key locality in central Sonora. This site preserves the tectonic vestiges of the contact between the Sonora Allochthon and the southern Laurussian continental shelf. At this locality, Carboniferous deep-ocean facies of the Sonora Allochthon, considered a synorogenic succession included in the Rancho Nuevo Formation, are well exposed (Poole \\u0026amp; Amaya-Mart\\u0026iacute;nez, \\u003cspan citationid=\\\"CR72\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e; Poole \\u0026amp; Madrid, \\u003cspan citationid=\\\"CR74\\\" class=\\\"CitationRef\\\"\\u003e1988\\u003c/span\\u003e; Stevens et al., \\u003cspan citationid=\\\"CR99\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e). The Rancho Nuevo Formation includes deformed beds of quartzite, argillite, conglomerate, barite deposits and limestone (Stevens et al., \\u003cspan citationid=\\\"CR99\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e). Previous works with fusulinids, foraminifera and conodonts suggested a Middle Mississippian and Pennsylvanian age for these rocks (Poole et al., \\u003cspan citationid=\\\"CR75\\\" class=\\\"CitationRef\\\"\\u003e1983\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Poole \\u0026amp; Amaya-Mart\\u0026iacute;nez, \\u003cspan citationid=\\\"CR72\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eIn our study, 16 samples of limestone were collected within the area defined by the coordinates SW: 28\\u0026deg; 55' 8\\\" N, 109 \\u0026deg; 58' 27\\\" W - NE: 28\\u0026deg; 55' 34\\\" N, 109\\u0026deg; 57' 0\\\" W (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig3\\\" class=\\\"InternalRef\\\"\\u003e3\\u003c/span\\u003e). This area is about 100 km east of Hermosillo. The exposed rocks are dark bluish gray to light gray. Some horizons exhibit yellowish, brownish, and reddish colors. Rock samples were taken from intervals with minimum visible alteration to avoid weathering and diagenetic overprint. Due to the significant deformation in this region, constructing a stratigraphic column was complicated. However, based on previous geological and biostratigraphic studies (e.g., Poole et al., \\u003cspan citationid=\\\"CR78\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Stevens et al., \\u003cspan citationid=\\\"CR99\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e), the sampling points were selected along the best exposed Carboniferous rocks. To corroborate the dating of the rock, the samples from Cerro Las Rastras were processed to search for conodonts. About 20 kg of rocks were dissolved according to the methodology outlined by Jeppsson et al. (\\u003cspan citationid=\\\"CR49\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e) in a buffered acetic and formic acid solutions. Summary information about collected samples is described on Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003cdiv class=\\\"gridtable\\\"\\u003e\\u003ctable float=\\\"Yes\\\" id=\\\"Tab1\\\" border=\\\"1\\\"\\u003e \\u003ccaption language=\\\"En\\\"\\u003e \\u003cdiv class=\\\"CaptionNumber\\\"\\u003eTable 1\\u003c/div\\u003e \\u003cdiv class=\\\"CaptionContent\\\"\\u003e \\u003cp\\u003eLocalization, lithology, and biostratigraphic age based on the conodont genus or genus associations found in the collected samples of the SW sector of the Cerro Las Rastras.\\u003c/p\\u003e \\u003c/div\\u003e \\u003c/caption\\u003e \\u003ccolgroup cols=\\\"4\\\"\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c1\\\" colnum=\\\"1\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c2\\\" colnum=\\\"2\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c3\\\" colnum=\\\"3\\\"\\u003e\\u003c/div\\u003e \\u003cdiv align=\\\"left\\\" class=\\\"colspec\\\" colname=\\\"c4\\\" colnum=\\\"4\\\"\\u003e\\u003c/div\\u003e \\u003cthead\\u003e \\u003ctr\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003eSamples /\\u003c/p\\u003e \\u003cp\\u003eFormation\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003eLatitude /\\u003c/p\\u003e \\u003cp\\u003eLongitude\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLithology\\u003c/p\\u003e \\u003c/th\\u003e \\u003cth align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003eConodonts genus or genus association /\\u003c/p\\u003e \\u003cp\\u003eBiostratigraphic Age\\u003c/p\\u003e \\u003c/th\\u003e \\u003c/tr\\u003e \\u003c/thead\\u003e \\u003ctbody\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR01 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'8.74\\\"N/\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;58'27.06\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eIdiognathodus, Gondolella\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle Pennsylvanian (Desmoinesian)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR02 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'9.35\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;58'25.91\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eIdiognathodus, Gondolella\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle Pennsylvanian (Desmoinesian)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR03 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'9.01\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;58'20.01\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone with chert nodules\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR04 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'13.33\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;58'6.59\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eIdiognathoides, Idiognathodus, Gondolella, Streptognathodus\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle Pennsylvanian (Desmoinesian)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR05 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'26.94\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;56'58.62\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR06 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'28.58\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'0.93\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR07 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'27.26\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'2.71\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eStreptognathodus\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle to Late? Pennsylvanian (Desmoinesian to Virgilian?)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR08 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'29.20\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'22.67\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eIdiognathodus\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle to Late? Pennsylvanian (Desmoinesian to Virgilian?)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR09 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'29.97\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'16.61\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR10 /\\u003c/p\\u003e \\u003cp\\u003eSierra Mart\\u0026iacute;nez Group (?)\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'34.54\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'14.83\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eNeopolygnathus\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003elatest Devonian \\u0026ndash; Early Mississippian\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR11 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'33.06\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'25.55\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eIdiognathodus, Gondolella\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle Pennsylvanian (Desmoinesian)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR12 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'28.53\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'40.89\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eLimestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR13A /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'27.00\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'35.40\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR13B /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'28.02\\\"N /\\u003c/p\\u003e \\u003cp\\u003e109\\u0026deg;57'33.88\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR14\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'26.70\\\"N / 109\\u0026deg;57'22.29\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSiltstone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e-\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003ctr\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c1\\\"\\u003e \\u003cp\\u003e22LR15 /\\u003c/p\\u003e \\u003cp\\u003eRancho Nuevo\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c2\\\"\\u003e \\u003cp\\u003e28\\u0026deg;55'28.30\\\"N / 109\\u0026deg;57'23.42\\\"W\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c3\\\"\\u003e \\u003cp\\u003eSandy Limestone\\u003c/p\\u003e \\u003c/td\\u003e \\u003ctd align=\\\"left\\\" colname=\\\"c4\\\"\\u003e \\u003cp\\u003e\\u003cem\\u003eIdiognathodus\\u003c/em\\u003e /\\u003c/p\\u003e \\u003cp\\u003eMiddle to Late? Pennsylvanian (Desmoinesian to Virgilian?)\\u003c/p\\u003e \\u003c/td\\u003e \\u003c/tr\\u003e \\u003c/tbody\\u003e \\u003c/colgroup\\u003e \\u003c/table\\u003e\\u003c/div\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003e2. Isotopic analysis\\u003c/h3\\u003e\\n\\n\\u003ch3\\u003e1. Sample preparation\\u003c/h3\\u003e\\n\\u003cp\\u003eA total of 38 sample levels of the La Joya section were involved in this study. In the case of Cerro Las Rastras, 16 sample levels were processed. About 1 g of rock sample was obtained using a diamond-tipped drill (Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e; Brand et al., \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). Powder was extracted directly from the carbonate matrix, avoiding altered surfaces and calcite veins. This procedure was carrried out at the ConoLAB, Estaci\\u0026oacute;n Regional del Noroeste of the Instituto de Geolog\\u0026iacute;a (UNAM).\\u003c/p\\u003e\\n\\u003ch3\\u003e2. Stable isotope analysis\\u003c/h3\\u003e\\n\\u003cp\\u003eCarbon and oxygen isotope analysis were performed at the Laboratory of Stable Isotope Analysis of the Unidad Acad\\u0026eacute;mica de Ciencias y Tecnolog\\u0026iacute;a de Yucat\\u0026aacute;n-UNAM (n\\u0026thinsp;=\\u0026thinsp;302, Sierra Agua Verde, La Joya section, averaging repetitions for each stratigraphic level) and at the Instituto de Geolog\\u0026iacute;a-UNAM (n\\u0026thinsp;=\\u0026thinsp;16, Cerro Las Rastras). In both cases, the analysis was carried out using a GasBench II device connected to a Thermo Scientific Delta V Plus mass spectrometer and to a Thermo Finnigan MAT 253 mass spectrometer, respectively. About 100\\u0026ndash;200 \\u0026micro;g of powders were treated with CaCO\\u003csub\\u003e3\\u003c/sub\\u003e-H\\u003csub\\u003e3\\u003c/sub\\u003ePO\\u003csub\\u003e4\\u003c/sub\\u003e at 25\\u0026deg;C to release CO\\u003csub\\u003e2\\u003c/sub\\u003e from carbonates. Isotopic values are presented in δ-notation and reported relative to the Vienna Pee Dee Belemnite (VDPB) standard. Reference materials used for quality control were the following: LAIE-CACO3 (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=-18.6\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-20.7\\u0026permil;), LAIE-34 (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=2.5\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-2.4\\u0026permil;), NBS18 (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=-5.1\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-23.1\\u0026permil;), LAIE-QC (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=1.6\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-5.6\\u0026permil;), IAEA-603 (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=2.5\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-2.4\\u0026permil;), NBS 19 (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=2.09\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-1.65\\u0026permil;), NBS 18 (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=-4.90\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-22.69\\u0026permil;), LSVEC (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=-46.44\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-26.31\\u0026permil;), TS (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=2.05\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-1.79\\u0026permil;), CaCO3 Sigma Aldrich (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=-8.01\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-20.92\\u0026permil;) and CaCO\\u003csub\\u003e3\\u003c/sub\\u003e Merck (δ\\u003csup\\u003e13\\u003c/sup\\u003eC=-46.62\\u0026permil;, δ\\u003csup\\u003e18\\u003c/sup\\u003eO=-16.12\\u0026permil;). The reproducibility of the measurements was better than 0.05\\u0026permil; for δ\\u003csup\\u003e18\\u003c/sup\\u003eO and 0.06\\u0026permil; for δ\\u003csup\\u003e13\\u003c/sup\\u003eC, for the Sierra Agua Verde samples, and better than 0.15\\u0026permil; for δ\\u003csup\\u003e13\\u003c/sup\\u003eC and 0.12\\u0026permil; for δ\\u003csup\\u003e18\\u003c/sup\\u003eO, for the Cerro Las Rastras samples.\\u003c/p\\u003e\"},{\"header\":\"RESULTS\",\"content\":\"\\u003cdiv id=\\\"Sec10\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e4.1. Sierra Agua Verde\\u003c/h2\\u003e \\u003cp\\u003eThe δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values of the La Joya section range from \\u0026minus;\\u0026thinsp;2.88 to +\\u0026thinsp;3.30\\u0026permil; (δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e mean: -2.60 to +\\u0026thinsp;3.15\\u0026permil;) and from \\u0026minus;\\u0026thinsp;15.54 to -2.71\\u0026permil; (δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e mean: -15.46 to -3.74\\u0026permil;), respectively (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e). The Visean δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e record is characterized by a decreasing trend from the highest values of the whole record to a value of 0.00\\u0026permil;, at level 75.59 m. A subsequent increase occurs to a value of 2.17\\u0026permil; throughout the upper part of the Visean. Above this, a decreasing trend down to a value of -1.45\\u0026permil; at level 123 m and is maintained across the Serpukhovian and the Lower Bashkirian (i.e., middle-upper Chesterian and lower Morrowan). A slight decrease in the lower part of the Pennsylvanian is capped by a positive shift of 0.67\\u0026permil; at level 191 m. Finally, in the upper part of the Pennsylvanian section, the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e curve decreases (down to -2.60\\u0026permil;) followed by a return to more positive values.\\u003c/p\\u003e \\u003cp\\u003eOn the other hand, the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values begin with a negative trend that reaches the lowest value of the whole record (down to -15.54\\u0026permil;). Later, the record shows a positive trend until almost the middle part of the Visean (Meramecian), up to a maximum of -4.67\\u0026permil;. Upwards, within the upper Visean (lower Chesterian) and lower Bashkirian (lower Morrowan) interval, the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e curve records a trend towards lower values (down to -11.89\\u0026permil;). Subsequently, a positive shift with an amplitude of 9.07\\u0026permil; at middle Bashkirian is followed by a negative trend that continues throughout the Bashkirian-Moscovian boundary.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e \\u003cdiv id=\\\"Sec11\\\" class=\\\"Section2\\\"\\u003e \\u003ch2\\u003e4.2. Cerro Las Rastras\\u003c/h2\\u003e \\u003cp\\u003eThe samples from the SW sector of the Cerro Las Rastras exhibit a δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and the δ\\u003csup\\u003e13\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values range from \\u0026minus;\\u0026thinsp;9.65 to +\\u0026thinsp;2.68\\u0026permil; and from \\u0026minus;\\u0026thinsp;12.15 to +\\u0026thinsp;0.46\\u0026permil;, respectively (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). The isotopic distribution cloud of the deep-basin samples from Cerro Las Rastras is very similar to that of the shallow marine environments from Sierra Agua Verde. The oxygen and carbon isotopic records show no visible pattern in the data distribution. All data presented in this paper is available online in the Guti\\u0026eacute;rrez et al., (\\u003cspan citationid=\\\"CR38\\\" class=\\\"CitationRef\\\"\\u003e2024\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eConodonts were identified in samples 22LR-01, 22LR-02, 22LR-04, 22LR-07, 22LR-08 22LR-11 and 22LR-15, including different genera, such as \\u003cem\\u003eIdiognathoides\\u003c/em\\u003e, \\u003cem\\u003eIdiognathodus, Streptognathodus\\u003c/em\\u003e and \\u003cem\\u003eGondolella\\u003c/em\\u003e (Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e6\\u003c/span\\u003e). In particular, \\u003cem\\u003eIdiognathodus\\u003c/em\\u003e and \\u003cem\\u003eStreptognathodus\\u003c/em\\u003e indicate an age corresponding to the Middle to Late Pennsylvanian, a period characterized by their greatest abundance and diversification. Samples which contain only one of these genera (e.g., 22LR-7, 22LR-8, 22LR-15; Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e6\\u003c/span\\u003e) may correspond to an age range between Desmoinesian and Virgilian (Middle to Late Pennsylvanian). In other hand, samples that additionally contain the genus \\u003cem\\u003eGondolella\\u003c/em\\u003e (e.g., 22LR-1; 22LR-2; 22LR-4; 22LR-11), a genus identified from the base of the Middle Pennsylvanian (late Atokan) and often associated with genera such as \\u003cem\\u003eIdiognathodus\\u003c/em\\u003e and/or \\u003cem\\u003eStreptognathodus\\u003c/em\\u003e, could constrain the age of these samples to the Desmoinesian (Middle Pennsylvanian). Therefore, the conodont genera or assemblage for each sample indicates Middle to Late Pennsylvanian age (Desmoinesian to Virgilian; Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e6\\u003c/span\\u003e) for the SW sector of Cerro Las Rastras and which in several localities of the North American Mid-Continent have also been reported (e.g., Lost Branch cyclothem; Barrick et al., \\u003cspan citationid=\\\"CR6\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e; Dunn, \\u003cspan citationid=\\\"CR30\\\" class=\\\"CitationRef\\\"\\u003e1970\\u003c/span\\u003e). Only the 22LR-10 sample contains latest Devonian to early Mississippian polygnathid conodonts, specifically of the \\u003cem\\u003eNeopolygnathus\\u003c/em\\u003e genus (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e6\\u003c/span\\u003e), confirming an older stratigraphic unit, previously described as carbonate shelf, which consists of Upper Devonian to Pennsylvanian rocks (Poole et al., \\u003cspan citationid=\\\"CR73\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). Therefore, sample 22LR-10 is beyond the scope of the present study. No conodonts were found in the remaining nine samples. In addition, sample 22LR-14 is also outside the scope of this work as it is a siltstone and not a limestone.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003c/div\\u003e\"},{\"header\":\"DISCUSSION\",\"content\":\"\\n\\u003ch3\\u003e1. Impact of diagenetic alteration on isotopic δO and δC imprints\\u003c/h3\\u003e\\n\\u003cp\\u003ePost-depositional diagenetic alteration may modify the primary isotope signal of marine carbonates. For instance, meteoric-vadose diagenesis generally causes a depletion of the carbon and oxygen isotope values, which results in a strong covariation between δ\\u003csup\\u003e18\\u003c/sup\\u003eO and δ\\u003csup\\u003e13\\u003c/sup\\u003eC values (Allan \\u0026amp; Matthews, \\u003cspan citationid=\\\"CR2\\\" class=\\\"CitationRef\\\"\\u003e2009\\u003c/span\\u003e; Swart, \\u003cspan citationid=\\\"CR101\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e; Di Lucia et al., \\u003cspan citationid=\\\"CR29\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). The scatterplot of the δ\\u003csup\\u003e18\\u003c/sup\\u003eO and δ\\u003csup\\u003e13\\u003c/sup\\u003eC values for the studied samples show that these parameters have no significant correlation (La Joya: r\\u0026thinsp;=\\u0026thinsp;0. 0001: Cerro Las Rastras: r\\u0026thinsp;=\\u0026thinsp;0.0321). This is consistent with the lack of correlation also found by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) in the La Joya section (r\\u0026thinsp;=\\u0026thinsp;0.14), where variations in signatures and absolute values occur as one ascends stratigraphically which closely resembles the new data herein documented (i.e., δ\\u003csup\\u003e13\\u003c/sup\\u003eC: r\\u0026thinsp;=\\u0026thinsp;0.90; δ\\u003csup\\u003e18\\u003c/sup\\u003eO: r\\u0026thinsp;=\\u0026thinsp;0.88) (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig7\\\" class=\\\"InternalRef\\\"\\u003e7\\u003c/span\\u003e). In addition, to discard analytical errors, all the above indicates that diagenetic transformations had no major impact in the δ\\u003csup\\u003e13\\u003c/sup\\u003eC values and they represent a primary marine signal. The records of our study are different from the global values reported in both, Carboniferous brachiopods and carbonates rocks, which range between \\u0026minus;\\u0026thinsp;2\\u0026permil; and +\\u0026thinsp;8\\u0026permil; (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e) (e.g., Bruckschen et al., \\u003cspan citationid=\\\"CR16\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Mii et al., \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e; Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Grossman et al., \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Buggisch et al., \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e, \\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e; Brand et al., \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e; Qie et al., \\u003cspan citationid=\\\"CR83\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e). The δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values obtained in this study exhibit trends and absolute values comparable to those reported in limestones from West USA (Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e; Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e) (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig8\\\" class=\\\"InternalRef\\\"\\u003e8\\u003c/span\\u003e). Although the obtained δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e record in this study reaches lower values than the documented from Carboniferous brachiopods (-8 to 0\\u0026permil; from Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e; Grossman et al., \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; and Brand et al., \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e) and Carboniferous carbonates rocks from South China (-6.9 to -3.0\\u0026permil; from Zhao \\u0026amp; Zheng, 2014), the overall trends in our δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e are similar to those observed in the western USA (Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig8\\\" class=\\\"InternalRef\\\"\\u003e8\\u003c/span\\u003e). Moreover, in the Visean interval, both records display a strong depletion (δ\\u0026sup1;\\u003csup\\u003e8\\u003c/sup\\u003eO \\u0026lt; -10\\u0026permil;), which may suggest that the NW regions of Mexico and USA were affected by the same processes that controlled the isotopic signatures. According to some authors it is suggested that δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values \\u0026lt; -6\\u0026permil; can represent the recrystallization and isotope resetting under the influence of \\u003csup\\u003e18\\u003c/sup\\u003eO depleted fluids (e.g., Hayes, \\u003cspan citationid=\\\"CR41\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e). In addition, Batt et al. (\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e) suggested that δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values lower than \\u0026minus;\\u0026thinsp;10\\u0026permil; in West USA limestones indicate a diagenetic overprint. In the La Joya section, samples recording the negative shift of δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e at the lower part of the Visean do not show visible diagenetic alteration (silicification, oxidization, and/or dolomitization). However, it should be noted that this anomaly in δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values coincides with the environmental model proposed by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e), which suggest that the La Joya sediments experimented a change in the depositional setting from external platform margin to a restricted lagoon. In this sense, the depth shift on the La Joya basin could have been the major environment factor which facilitated the development of meteoric waters, triggering an enhanced input of water enriched in \\u003csup\\u003e16\\u003c/sup\\u003eO by fluvial and pluvial discharges (Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Keller et al., \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e; Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e). Therefore, the strong decrease in δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e records does not coincide with a significant decrease in δ\\u0026sup1;\\u0026sup3;C\\u003csub\\u003ecarb\\u003c/sub\\u003e, due to the meteoric waters that affected δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e could have been mostly from rainwater without organic matter significative supply (e.g., Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e; Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003e2. Comparison of δC and δO records in Central Sonora\\u003c/h3\\u003e\\n\\u003cp\\u003eVillanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) estimated the δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO values in Sierra Agua Verde limestones. Their interpretations were not entirely congruent with the global MPB climatology proposed by other studies. Some authors suggest that the Late Paleozoic Ice Age was caused by the decrease in pCO\\u003csub\\u003e2\\u003c/sub\\u003e and the increase in seasonality (Raymond et al., \\u003cspan citationid=\\\"CR85\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e; Isbell et al., \\u003cspan citationid=\\\"CR48\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e; Limarino et al., \\u003cspan citationid=\\\"CR57\\\" class=\\\"CitationRef\\\"\\u003e2006\\u003c/span\\u003e; Fielding et al., \\u003cspan citationid=\\\"CR33\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). Thus, it would be expected that carbonate δ\\u003csup\\u003e18\\u003c/sup\\u003eO records present a positive excursion during MPB, due to the loss of global \\u003csup\\u003e16\\u003c/sup\\u003eO stored in polar ice sheets, along with a corresponding positive excursion in δ\\u003csup\\u003e13\\u003c/sup\\u003eC carbonate records (e.g., Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e; Mii et al., \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e). However, in previous oxygen and carbon isotopes analysis conducted by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e), both δ\\u003csup\\u003e18\\u003c/sup\\u003eO and δ\\u003csup\\u003e13\\u003c/sup\\u003eC data show an opposite trend.\\u003c/p\\u003e \\u003cp\\u003eThe strong correlation between the Sierra Agua Verde previous and new records, and the isotopic data from Cerro Las Rastras (as shown in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e\\u003cspan type=\\\"Underline\\\" class=\\\"Underline\\\" name=\\\"Emphasis\\\"\\u003e)\\u003c/span\\u003e, also in central Sonora, provides evidence of a reliable representation of the Carboniferous isotopic signal in rock and precludes methodological errors. However, it is important to mention that, according to biostratigraphic age of conodonts found in some samples from Cerro Las Rastras, the isotopic records could be reflecting the effects of the last glacial pulse of the Carboniferous, in the Late Pennsylvanian stage.\\u003c/p\\u003e \\u003cp\\u003eLikewise, it should also be highlighted that sample 22LR-04 presents a very low δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e value (-9.6\\u0026permil;), moving it away from the dispersion of most of the Cerro Las Rastras samples in Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e. A high concentration of organic matter in the sedimentary environment could explain low δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values ​​due to \\u003csup\\u003e12\\u003c/sup\\u003eC enrichment (Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). However, we do not have any TOC studies. It would be interesting to do so in future work. If that were the case, this would be consistent with the high abundance of conodonts found at this level (240 elements per kilogram of dissolved rock) and the resulting conodont biofacies at this stratigraphic level, since they suggest deep basin sedimentary environments, where organic remains could accumulate and influence during diagenesis.\\u003c/p\\u003e\\n\\u003ch3\\u003e3. δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e records from Central Sonora and Global comparisons\\u003c/h3\\u003e\\n\\u003cp\\u003eThe δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e data from Sierra Agua Verde can be separated into two groups (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). The first is dominated by Visean data and characterized by positive δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values, whereas the second grouped most of the Serpukhovian, Bashkirian and Moscovian records, and is distinguished by almost exclusively negative δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values. This could be explained by local and global environmental changes that occurred during the Carboniferous (Chen et al., \\u003cspan citationid=\\\"CR22\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Chen \\u0026amp; Sharma, \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e; Villanueva-Olea et al., \\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). To understand the possible causes that could have defined these patterns in the distribution of isotopic values, it is necessary to comprehend the processes that affect the behavior of the isotopic ratios of oxygen and carbon in carbonate rocks.\\u003c/p\\u003e\\n\\u003ch3\\u003e1. Correlation between δC, δO and local processes\\u003c/h3\\u003e\\n\\u003cp\\u003eThe precipitation of carbonates occurs at or near isotopic equilibrium from natural waters. The variability of marine δ\\u003csup\\u003e13\\u003c/sup\\u003eC can be associated to primary productivity due to the biologic preference to \\u003csup\\u003e12\\u003c/sup\\u003eC (Algeo et al., \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1995\\u003c/span\\u003e; Berner \\u0026amp; Barron, \\u003cspan citationid=\\\"CR11\\\" class=\\\"CitationRef\\\"\\u003e1984\\u003c/span\\u003e; Hoefs, \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Popp et al., \\u003cspan citationid=\\\"CR81\\\" class=\\\"CitationRef\\\"\\u003e1986\\u003c/span\\u003e). Environmental parameters such as temperature, salinity, depth and substrate can affect the ocean's carbon (Bruckschen et al., 1999; Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e). However, it has been shown that their direct impact on marine δ\\u003csup\\u003e13\\u003c/sup\\u003eC is minimal and their main influence lies in nutrient availability for marine life to grow (Saltzman, \\u003cspan citationid=\\\"CR92\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). δ\\u003csup\\u003e18\\u003c/sup\\u003eO is strongly controlled by the interactions with meteoric waters, evaporation, and water masses (Craig \\u0026amp; Gordon, \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e1965\\u003c/span\\u003e; Hoefs, \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Horita \\u0026amp; Wesolowski, \\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e1994\\u003c/span\\u003e). In addition, early diagenetic processes can also affect the isotopic records of δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO in carbonated rocks (Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Swart \\u0026amp; Eberli, \\u003cspan citationid=\\\"CR102\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; H\\u0026ouml;nig \\u0026amp; John, \\u003cspan citationid=\\\"CR44\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). Some authors suggest that the constant exposure of sediments to meteoric waters and organic matter can diminish values of δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO in carbonate rocks, this is due to a stabilization during early diagenesis with the light oxygen of rainwater and the \\u003csup\\u003e12\\u003c/sup\\u003eC enriched organic matter. Thus, the joint study of δ\\u0026sup1;\\u0026sup3;C and δ\\u003csup\\u003e18\\u003c/sup\\u003eO is commonly used as a tool to help understand the processes that control the isotopic records, especially to identify the effect of diagenesis (Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Keller et al., \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eTo help understand the processes that control the oxygen and carbon isotopic records from Sierra Agua Verde, the trends of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e were reviewed between each observation, one by one, to identify those intervals where both records increase, decrease, or present opposite trends. A comparison with the paleobathymetry of the succession (Villanueva-Olea et al., \\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) was also incorporated into this review (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e9\\u003c/span\\u003e). Evidence on microfacies and sedimentary facies is shown and discussed in depth in the work of Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eThrough the isotopic records are presented some stratigraphic intervals where δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e show a simultaneous increasing trend (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e9\\u003c/span\\u003e at 35.54\\u0026ndash;37.72, 75.59\\u0026ndash;77.33 and 95.95\\u0026ndash;98.23 m in the Visean, 114.91-120.05 m in the Serpukhovian, and 168.44-191.33, 204.29\\u0026ndash;206.30 and 216.14-223.28 m in the Bashkirian). This simultaneous behavior can be associated with a favored productivity and the presence of drier conditions. The increment of δ\\u003csup\\u003e13\\u003c/sup\\u003eC can be caused by the loss of the environmental \\u003csup\\u003e12\\u003c/sup\\u003eC due to the isotopic fractionation of photosynthesis (Porter et al., \\u003cspan citationid=\\\"CR82\\\" class=\\\"CitationRef\\\"\\u003e2014\\u003c/span\\u003e; Schmid et al., \\u003cspan citationid=\\\"CR96\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Babalola et al., \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e). The increased δ\\u003csup\\u003e18\\u003c/sup\\u003eO can be triggered by processes like evaporation, interactions with deep water masses and/or a limited input of meteoric waters (Craig \\u0026amp; Gordon, \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e1965\\u003c/span\\u003e; Hoefs, \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Horita \\u0026amp; Wesolowski, \\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e1994\\u003c/span\\u003e). The paleobathymetry by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) has helped to identify the processes that could have enhanced the increases in δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e, whether the area was in deeper or shallower zones. For example, around the end of the Visean and the middle Serpukhovian sections, in Sierra Agua Verde are dominant shallower conditions of restricted and open lagoon, which coincides with a simultaneous increase in δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e records from that locality; it is possible that those periods have been characterized by an increase in productivity and an increased evaporation due to the shallow environments, and possibly a limited input of rainwater, allowing the increase in the isotopic records values (e.g., Babalola et al., \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eDespite the previously discussed trends, it is possible to find stratigraphic intervals where δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e present decrements in values (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e9\\u003c/span\\u003e at 1.59\\u0026ndash;2.80, 5.89\\u0026ndash;8.14, 31.01\\u0026ndash;32.82 and 82.50-95.95 m in Visean, 101.50-114.91 and 120.05-123.29 m in Serpukhovian, 130.61-168.44, 191.33-204.29 and 206.30-216.14 m in Bashkirian, and 223.28-238.15 m in Moscovian). The simultaneous decreasing of carbon and oxygen isotopic records trends could be interpreted as a period of abundant inflows of meteoric waters (Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e; Keller et al., \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). This isotopic pattern, indicative of meteoric water influx, is prevalent in the Sierra Agua Verde records. This is congruent with the paleogeographic configurations of the region during Carboniferous, when Sierra Agua Verde sediments were mostly shallow and exposed to meteoric waters (Villanueva-Olea et al., \\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) and were located in a paleoequatorial zone where rainfalls were common and strong (Blakey, \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eAn opposite correlation between δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e may reflect different situations than those discussed above. Those stratigraphic intervals where δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values have an increment and those of δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e decrease (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e9\\u003c/span\\u003e at 1.30\\u0026ndash;1.59, 32.82\\u0026ndash;33.69 and 81.04\\u0026ndash;82.50 m in Visean, 123.29-130.61 m in Serpukhovian, and 238.15-246.06 m in Moscovian) could be associated with high-productivity periods (Sass \\u0026amp; Kolodny, \\u003cspan citationid=\\\"CR95\\\" class=\\\"CitationRef\\\"\\u003e1972\\u003c/span\\u003e; Irwin et al., \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Geoffrey D. Thyne, James R. Boles, 1989). The decrements in δ\\u003csup\\u003e18\\u003c/sup\\u003eO values are generally associated with the input of rainwater (Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e; Keller et al., \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). In addition, the degradation of the produced organic matter release light oxygen in water that could contribute to the negative trend of the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e (Hudson, \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Irwin et al., \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Coleman, \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Mozley and Burns, 1993). These intervals of negative correlation, characterized by increasing δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and decreasing δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e, may indicate periods of high productivity and increased rainfall in the Sierra Agua Verde region.\\u003c/p\\u003e \\u003cp\\u003eStratigraphic intervals where δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e decreases and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e increases occur in La Joya Section (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig9\\\" class=\\\"InternalRef\\\"\\u003e9\\u003c/span\\u003e at 1.30\\u0026ndash;1.59, 5.89\\u0026ndash;8.14, 31.01\\u0026ndash;32.82, 35.54\\u0026ndash;37.75, 75.59\\u0026ndash;77.33 and 81.04\\u0026ndash;82.50 m in Visean, 101.50-111.55 m in Serpukhovian, and 268.36\\u0026ndash;270.00 m in Moscovian). Periods of low productivity could be associated with low δ\\u003csup\\u003e13\\u003c/sup\\u003eC values (Hudson, \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Irwin et al., \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Coleman, \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Peter S. Mozley, Stephen J. Burns, 1993). However, upwellings could be playing an important role in equatorial coasts, enhancing productivity, and supplying \\u003csup\\u003e12\\u003c/sup\\u003eC (Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e; Tian et al., \\u003cspan citationid=\\\"CR103\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). Organic matter degradation not only release \\u003csup\\u003e12\\u003c/sup\\u003eC, but also \\u003csup\\u003e16\\u003c/sup\\u003eO (Hudson, \\u003cspan citationid=\\\"CR46\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Irwin et al., \\u003cspan citationid=\\\"CR47\\\" class=\\\"CitationRef\\\"\\u003e1977\\u003c/span\\u003e; Coleman, \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Peter S. Mozley, Stephen J. Burns, 1993). If the degradation of organic matter was sufficient to see the contribution of \\u003csup\\u003e12\\u003c/sup\\u003eC in the carbon isotopic records, it is feasible to think that \\u003csup\\u003e16\\u003c/sup\\u003eO could also have been significant to be reflected in a decreasing δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e; therefore, it is possible that other factors may have stimulated the increment of δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values.\\u003c/p\\u003e \\u003cp\\u003eShallow conditions could benefit the water evaporation and loss of \\u003csup\\u003e16\\u003c/sup\\u003eO, and deeper environments might facilitate interaction with deep water masses and reduce contact with meteoric waters. The evaporation due to warming is not congruent with the upwelling occurrence suggested for western Laurussia (Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) and some equatorial Paleo-Tethyan localities (Buggisch et al., \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Grossman et al., \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Tian et al., \\u003cspan citationid=\\\"CR103\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). An increase in local temperatures could have stratified the water column, preventing the upwelling occurrence (e.g., Grossman et al., \\u003cspan citationid=\\\"CR35\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; H.-S. Mii et al., \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e). Thus, it is possible that the evaporation has occurred due to the establishment of drier conditions, where the input of meteoric waters was reduced, and the low relative humidity has led the escape of light water molecules (e.g., Wright \\u0026amp; Vanstone, \\u003cspan citationid=\\\"CR107\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Haq \\u0026amp; Schutter, \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Monta\\u0026ntilde;ez \\u0026amp; Poulsen, \\u003cspan citationid=\\\"CR64\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003e2. Visean cluster\\u003c/h3\\u003e\\n\\u003cp\\u003eIn Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e it is possible to appreciate that most of the Visean isotopic data from La Joya groups are on the positive side of the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e axis. This happens because the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e record starts with relatively high values to follow a decreasing trend along the way (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig4\\\" class=\\\"InternalRef\\\"\\u003e4\\u003c/span\\u003e). Otherwise, the record of δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e presents a positive trend along the Visean part of the record. As mentioned previously, periods with this contrary behavior can be associated with an increase in upwelling occurrence and evaporation (e.g., Coleman, \\u003cspan citationid=\\\"CR24\\\" class=\\\"CitationRef\\\"\\u003e1993\\u003c/span\\u003e; Haq \\u0026amp; Schutter, \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Monta\\u0026ntilde;ez \\u0026amp; Poulsen, \\u003cspan citationid=\\\"CR64\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e; Mozley \\u0026amp; Burns, 1993).\\u003c/p\\u003e \\u003cp\\u003eDuring the Mississippian, paleobotanical evidence suggests an increase in temperature and precipitations in equatorial regions (Raymond et al., \\u003cspan citationid=\\\"CR85\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e; Ross \\u0026amp; Ross, \\u003cspan citationid=\\\"CR88\\\" class=\\\"CitationRef\\\"\\u003e1985\\u003c/span\\u003e). These conditions led to the expansion of tropical forests and jungles (Algeo et al., \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1995\\u003c/span\\u003e). The proliferation of vascular plants and root penetration increased soil weathering; in consequence, the nutrient flux enhanced in oceans and global marine productivity was favored (Algeo et al., \\u003cspan citationid=\\\"CR1\\\" class=\\\"CitationRef\\\"\\u003e1995\\u003c/span\\u003e). The growth of the plants around the world led to the formation and expansion of carbon summits, creating, and increasing new reservoirs that sequestered \\u003csup\\u003e12\\u003c/sup\\u003eC from oceans and atmosphere (Berner, \\u003cspan citationid=\\\"CR10\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e). The global loss of \\u003csup\\u003e12\\u003c/sup\\u003eC is reflected in the Visean positive trend of the δ\\u003csup\\u003e13\\u003c/sup\\u003eC records from carbonate bulk from Europe (Buggisch et al., \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e) and brachiopods from Russia (Bruckschen \\u0026amp; Veizer, \\u003cspan citationid=\\\"CR15\\\" class=\\\"CitationRef\\\"\\u003e1997\\u003c/span\\u003e; Grossman et al., \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Korte et al., \\u003cspan citationid=\\\"CR54\\\" class=\\\"CitationRef\\\"\\u003e2005\\u003c/span\\u003e; H.-S. Mii et al., \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e), with both record values oscillating between ~\\u0026thinsp;+\\u0026thinsp;1.5 and +\\u0026thinsp;3.5\\u0026permil; (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig10\\\" class=\\\"InternalRef\\\"\\u003e10\\u003c/span\\u003e). Instead, the bulk carbon isotopic record from Sierra Agua Verde presents a wider range of values (from ~\\u0026thinsp;0\\u0026permil; to +\\u0026thinsp;3.13\\u0026permil;) and a decreasing general trend along Visean section. Brachiopods δ\\u003csup\\u003e13\\u003c/sup\\u003eC record from West USA (Brand et al., \\u003cspan citationid=\\\"CR14\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e) and bulk carbonate δ\\u003csup\\u003e13\\u003c/sup\\u003eC records from South China (Buggisch et al., \\u003cspan citationid=\\\"CR18\\\" class=\\\"CitationRef\\\"\\u003e2011\\u003c/span\\u003e; Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e) and West USA (Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) also present the decreasing trend and intervals of values\\u0026thinsp;~\\u0026thinsp;from 0 to +\\u0026thinsp;4\\u0026permil; and ~\\u0026thinsp;from \\u0026minus;\\u0026thinsp;1.9 to +\\u0026thinsp;3.2\\u0026permil; respectively (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig10\\\" class=\\\"InternalRef\\\"\\u003e10\\u003c/span\\u003e). The behavior of the variation of the upper part of these records is relatively similar to the Visean part of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e. The Visean part of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e may represent the upper part of Visean age. The differences in behavior and magnitude between Europe and Russia with West USA, South China and Sierra Agua Verde could be explained from a paleogeographic perspective. Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) suggest that the differences between the isotopic records from La Joya and those from around the world could be caused by the formation of upwelling zones in Sierra Agua Verde. They propose that the upwelling zones have been formed by reorganizing the ocean circulation patterns reported in Western Laurussia (Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). To robustly analyze this hypothesis, it is necessary to recognize the global oceanographic and climatological context of the Central Sonora region during the Carboniferous. During Visean, Southern China and Western USA were located in tropical regions while Russia and Europe were in higher latitudes (Blakey, \\u003cspan citationid=\\\"CR13\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). Kelly et al. (\\u003cspan citationid=\\\"CR53\\\" class=\\\"CitationRef\\\"\\u003e1990\\u003c/span\\u003e) indicated an increment in the latitudinal gradient of temperatures along the world during this age. Contrasting the tropical conditions proposed for equatorial regions (Raymond, \\u003cspan citationid=\\\"CR84\\\" class=\\\"CitationRef\\\"\\u003e1985\\u003c/span\\u003e; Raymond et al., \\u003cspan citationid=\\\"CR85\\\" class=\\\"CitationRef\\\"\\u003e1989\\u003c/span\\u003e), some authors reported a rapid fall of the global sea level as a signal of the onset of Gondwana glaciation (e.g., Smith \\u0026amp; Fred Read, \\u003cspan citationid=\\\"CR97\\\" class=\\\"CitationRef\\\"\\u003e2000\\u003c/span\\u003e; Wright \\u0026amp; Vanstone, \\u003cspan citationid=\\\"CR107\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Rygel et al., \\u003cspan citationid=\\\"CR89\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). The decline in tropical foraminifer diversity (Kalvoda, \\u003cspan citationid=\\\"CR51\\\" class=\\\"CitationRef\\\"\\u003e2002\\u003c/span\\u003e; Davydov et al., \\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e) and the glacial deposits in Gondwana support the decrease in temperatures (Buggisch et al., \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Limarino et al., \\u003cspan citationid=\\\"CR57\\\" class=\\\"CitationRef\\\"\\u003e2006\\u003c/span\\u003e). The latitudinal gradient of temperatures may have intensified trade winds and enhanced upwellings, as reported in western Laurussia (Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e; Saltzman, \\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) and some equatorial Paleo-Tethyan localities (Buggisch et al., \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Grossman et al., \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Tian et al., \\u003cspan citationid=\\\"CR103\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). Even though the increased occurrence of upwellings in tropical paleoregions could have increased productivity in equatorial seaway locations (i.e., higher δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e), upwelling waters are known to present higher concentrations of nutrients and \\u003csup\\u003e12\\u003c/sup\\u003eC, due to the degradation of organic matter (Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). The balance between productivity and upwellings could have influenced the differences in behavior and magnitude of δ\\u003csup\\u003e13\\u003c/sup\\u003eC records from different regions (Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e; Tian et al., \\u003cspan citationid=\\\"CR103\\\" class=\\\"CitationRef\\\"\\u003e2020\\u003c/span\\u003e). The gradual intensification of upwellings in equatorial regions could have caused an isotopic disequilibrium, where the \\u003csup\\u003e12\\u003c/sup\\u003eC supplied by upwellings could have been higher than its usage for organic matter production. Thus, the δ\\u003csup\\u003e13\\u003c/sup\\u003eC values of some tropical seas may have been decreasing during the Visean age, as suggested by δ\\u003csup\\u003e13\\u003c/sup\\u003eC records from West USA (Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e; Saltzman \\u0026amp; Thomas, \\u003cspan citationid=\\\"CR93\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e), South China (Liu et al., \\u003cspan citationid=\\\"CR58\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e) and Sierra Agua Verde.\\u003c/p\\u003e \\u003cp\\u003eSome authors suggest that the inputs of riverine waters could diminish δ\\u003csup\\u003e13\\u003c/sup\\u003eC values on carbonate records (Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Keller et al., \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e; Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e). The high concentration of \\u003csup\\u003e16\\u003c/sup\\u003eO in rainwater and river discharges, and the \\u003csup\\u003e12\\u003c/sup\\u003eC organic matter enriched riverine waters, simultaneously decrease the δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO values in sedimentary environments (Marshall, \\u003cspan citationid=\\\"CR59\\\" class=\\\"CitationRef\\\"\\u003e1992\\u003c/span\\u003e; Keller et al., \\u003cspan citationid=\\\"CR52\\\" class=\\\"CitationRef\\\"\\u003e2004\\u003c/span\\u003e; Al-Mojel et al., \\u003cspan citationid=\\\"CR3\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Salih et al., \\u003cspan citationid=\\\"CR90\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e; Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e). However, the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e trend is positive along the Visean part of the record. This probably suggests that the inputs of riverine waters did not contribute to the diminution of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e. This observation supports Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). They indicate that the La Joya region may have been relatively far from continental uplifts. They support this idea with the lack of sufficient input of siliciclastic in the platform. In this way, it is feasible to consider that the La Joya region had very little interaction with riverine meteoric waters.\\u003c/p\\u003e \\u003cp\\u003eContrary to the behavior of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e from this study, the Visean part of the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e record presents an increasing trend. Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) also report the increment in their Visean oxygen isotopic record from carbonate rocks. They argued that this behavior is explained by the global temperature decrement and the loss of global \\u003csup\\u003e16\\u003c/sup\\u003eO stored in polar ice sheets. However, this explanation applies to the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e of biogenic carbonates and fossil bioapatite (e.g., Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e; Mii et al., \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Batt et al., \\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e). Several authors suggest that the positive trends in δ\\u003csup\\u003e18\\u003c/sup\\u003eO from carbonate rocks are mostly caused by the loss of local \\u003csup\\u003e16\\u003c/sup\\u003eO in processes like evaporation, interactions with deep water masses and a limited input of meteoric waters (e.g. Craig \\u0026amp; Gordon, \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e1965\\u003c/span\\u003e; Horita \\u0026amp; Wesolowski, \\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e1994\\u003c/span\\u003e; Hoefs, \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e). According to Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig10\\\" class=\\\"InternalRef\\\"\\u003e10\\u003c/span\\u003e, during the Visean the isotopic signal can be explained by the presence of meteoric water. Similarly, the absence of the signal can be interpreted as periods of drought. This suggests that the interaction with meteoric waters may have been limited during the Visean. This is consistent with the hypothesis in several studies for the end of the Visean age, when an increase in seasonality coincided with a global tendency to drier conditions (Wright \\u0026amp; Vanstone, \\u003cspan citationid=\\\"CR107\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Haq \\u0026amp; Schutter, \\u003cspan citationid=\\\"CR40\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Monta\\u0026ntilde;ez \\u0026amp; Poulsen, \\u003cspan citationid=\\\"CR64\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e). Furthermore, Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) reported that around the end of the Visean and the Middle Serpukhovian sections, in Sierra Agua Verde there were dominant shallower conditions of restricted and open lagoon. It is possible that those periods have been characterized by increased evaporation due to the shallow environments, and possibly a limited input of rainwater, allowing the increase in the oxygen isotopic record values (e.g., Babalola et al., \\u003cspan citationid=\\\"CR5\\\" class=\\\"CitationRef\\\"\\u003e2023\\u003c/span\\u003e). Therefore, the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e record from the La Joya section supports the interpretation of a shift towards drier and more arid conditions in the Sierra Agua Verde region during the late Visean.\\u003c/p\\u003e \\u003cp\\u003e \\u003c/p\\u003e\\n\\u003ch3\\u003e3. Serpukhovian-Bashkirian-Moscovian cluster\\u003c/h3\\u003e\\n\\u003cp\\u003eSome studies based on sedimentary geochemistry suggest that the major continental glaciation on Gondwana began in late Visean and reached the first peak in the MBP (R. Chen \\u0026amp; Sharma, \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e; Fielding \\u0026amp; Frank, \\u003cspan citationid=\\\"CR32\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e; Monta\\u0026ntilde;ez \\u0026amp; Poulsen, \\u003cspan citationid=\\\"CR64\\\" class=\\\"CitationRef\\\"\\u003e2013\\u003c/span\\u003e). The global cooling of the LPIA led to the loss of habitat diversity, which may have caused the mass biodiversity extinction in global marine ecosystems (McGhee et al., \\u003cspan citationid=\\\"CR61\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e; Stanley \\u0026amp; Powell, \\u003cspan citationid=\\\"CR98\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e). This glacial event is recognized by the occurrence of various glacial deposits on Gondwana, a worldwide sea level fall, and a distinctive positive shift in δ\\u003csup\\u003e18\\u003c/sup\\u003eO records from conodont apatite and brachiopod calcite (H.-S. Mii et al., \\u003cspan citationid=\\\"CR63\\\" class=\\\"CitationRef\\\"\\u003e2001\\u003c/span\\u003e; Buggisch et al., \\u003cspan citationid=\\\"CR17\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; R. Chen \\u0026amp; Sharma, \\u003cspan citationid=\\\"CR23\\\" class=\\\"CitationRef\\\"\\u003e2016\\u003c/span\\u003e). In addition, a positive trend in carbonate δ\\u003csup\\u003e13\\u003c/sup\\u003eC records has been reported during MPB in different regions along Laurussia epicontinental seas (Popp et al., \\u003cspan citationid=\\\"CR81\\\" class=\\\"CitationRef\\\"\\u003e1986\\u003c/span\\u003e; H. Mii et al., \\u003cspan citationid=\\\"CR62\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e; Grossman et al., \\u003cspan citationid=\\\"CR36\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e; Dyer et al., \\u003cspan citationid=\\\"CR31\\\" class=\\\"CitationRef\\\"\\u003e2015\\u003c/span\\u003e). On the contrary, the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e record from Sierra Agua Verde presents a negative general trend with a particular variability. During the Serpukhovian, the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e record decreased until the early Bashkirian. Later, values exhibit a relatively abrupt increase (~\\u0026thinsp;2.31\\u0026permil;) to later decrease until reaching the lowest values (-2.6\\u0026permil;) of the whole record. Subsequently, the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e behavior turns into an increment trend during Upper Bashkirian that persists until the end of the record, during Moscovian. This behavior is similar to that presented in bulk δ\\u003csup\\u003e13\\u003c/sup\\u003eC records from Idaho and Nevada, reported by Batt et al. (\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e) and Saltzman (\\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) respectively (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig10\\\" class=\\\"InternalRef\\\"\\u003e10\\u003c/span\\u003e). Saltzman (\\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) suggests that MBP δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e records from Western North America are controlled mainly by nutrient availability and ocean productivity. Paleoatmospheric models suggest that the western tropical coasts of Laurussia were affected by strong wind fluxes that streamed from the Panthalassian high pressure system to the Intertropical Convergence Zone (Peyser \\u0026amp; Poulsen, \\u003cspan citationid=\\\"CR71\\\" class=\\\"CitationRef\\\"\\u003e2008\\u003c/span\\u003e). It is possible that the Sierra Agua Verde region has been affected by the same wind currents reported by Batt et al. (\\u003cspan citationid=\\\"CR9\\\" class=\\\"CitationRef\\\"\\u003e2007\\u003c/span\\u003e) and Saltzman (\\u003cspan citationid=\\\"CR91\\\" class=\\\"CitationRef\\\"\\u003e2003\\u003c/span\\u003e) for West USA. This climatological configuration could have produced variations in ocean productivity from the La Joya region, resulting in a δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e record relatively similar to those from West USA. This is consistent with the conclusions of Stewart et al. (\\u003cspan citationid=\\\"CR100\\\" class=\\\"CitationRef\\\"\\u003e1999\\u003c/span\\u003e), who mention how the Sierra Agua Verde region represents inner-shelf deposits very similar to those outcrops in California and Nevada.\\u003c/p\\u003e \\u003cp\\u003eThe negative trend of δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e could suggest the input of meteoric waters that bring \\u003csup\\u003e16\\u003c/sup\\u003eO into the Sierra Agua Verde paleoregion (e.g., Herath et al., \\u003cspan citationid=\\\"CR42\\\" class=\\\"CitationRef\\\"\\u003e2022\\u003c/span\\u003e). This is consistent with the proposal of several authors, who mentioned that a gradual rise in temperatures and ice melting incremented global humidity and tropical precipitations during Pennsylvanian (Bishop et al., \\u003cspan citationid=\\\"CR12\\\" class=\\\"CitationRef\\\"\\u003e2010\\u003c/span\\u003e; Gulbranson et al., \\u003cspan citationid=\\\"CR37\\\" class=\\\"CitationRef\\\"\\u003e2010\\u003c/span\\u003e; Limarino et al., \\u003cspan citationid=\\\"CR57\\\" class=\\\"CitationRef\\\"\\u003e2006\\u003c/span\\u003e; Davydov et al., \\u003cspan citationid=\\\"CR28\\\" class=\\\"CitationRef\\\"\\u003e2012\\u003c/span\\u003e). In addition, the paleobathymetric reconstruction of Sierra Agua Verde presents a predominance of shallow environments (restricted lagoon and open circulation lagoon) during Serpukhovian, Bashkirian and Moscovian ages (Villanueva-Olea et al., \\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e). These shallow conditions likely exposed the sediments to a greater influence from rainwater.\\u003c/p\\u003e \\u003cp\\u003eDue to the Cerro Las Rastras isotopic records do not cover the Mississippian period, it is not possible to appreciate a decrease in the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values that would allow identifying the signal of the interaction with meteoric waters. However, it is important to recall the similarity found between the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values of Cerro Las Rastras and the upper range of values from Sierra Agua Verde (Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig5\\\" class=\\\"InternalRef\\\"\\u003e5\\u003c/span\\u003e). This could suggest that the meteoric waters signal in the δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e record is not strong enough to affect deeper waters far from the coastline (e.g. Craig \\u0026amp; Gordon, \\u003cspan citationid=\\\"CR25\\\" class=\\\"CitationRef\\\"\\u003e1965\\u003c/span\\u003e; Hoefs, \\u003cspan citationid=\\\"CR43\\\" class=\\\"CitationRef\\\"\\u003e2018\\u003c/span\\u003e; Horita \\u0026amp; Wesolowski, \\u003cspan citationid=\\\"CR45\\\" class=\\\"CitationRef\\\"\\u003e1994\\u003c/span\\u003e). More studies that involve the deep-water Mississippian and Pennsylvanian rocks in Central Sonora are necessary to corroborate this hypothesis.\\u003c/p\\u003e\"},{\"header\":\"CONCLUSIONS\",\"content\":\"\\u003cp\\u003eThe congruence between Western US and Sierra Agua Verde δ\\u0026sup1;\\u0026sup3;C\\u003csub\\u003ecarb\\u003c/sub\\u003e records, and the similarity between central Sonora isotopic data, supports that the results obtained in this study have no significant diagenetic imprint and are good proxies to make consistent interpretations during the Mid-Carboniferous interval of the LPIA.\\u003c/p\\u003e \\u003cp\\u003eThe Carboniferous isotopic records from Central Sonora are similar to those from the West USA and South China but are different from those from Russia and Europe. These similarities and differences can be attributed to the Carboniferous position of these regions where Sonora, West USA and South China were located in equatorial regions, while Russia and Europe, in higher latitudes. In this way, the latitudinal differences result in different local processes that would modify the involved isotopic imprints.\\u003c/p\\u003e \\u003cp\\u003eThe relationship between central Sonora and West USA δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e records suggest that the same processes controlled the Mississippian isotopic signals of these regions. It is possible that the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e records of these regions were strongly ruled by upwellings and productivity while δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e was greatly controlled by the input of meteoric waters. The decrement trend of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and the gradual increment in δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e of the Visean section from Sierra Agua Verde records are consistent with the climate change reported for the age. The decrease in temperature, the increment in seasonality and latitudinal temperature gradient triggered the intensification of local upwellings and the limitation of rainfall in the region. On the other hand, the negative trend of δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e in La Joya records, presented in Serpukhovian, Bashkirian and Moscovian ages, could be suggesting the influence of meteoric waters that could have been apporting \\u003csup\\u003e16\\u003c/sup\\u003eO into central Sonora region. The decreasing trend of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e presents a similar variability to that occurring in bulk δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e records from Idaho and Nevada. It is possible that Sierra Agua Verde and West USA have been affected by the same wind currents which produced similar variations in ocean productivity. On the other hand, samples of the southwestern sector of Cerro Las Rastras confirm the Pennsylvanian age; however, the conodont association seem to suggest that different sample points may be younger (Desmoinesian - Virgilian; Middle - Late Pennsylvanian), and one sample even older (latest Devonian-earliest Mississippian; 22LR-10; Table\\u0026nbsp;\\u003cspan refid=\\\"Tab1\\\" class=\\\"InternalRef\\\"\\u003e1\\u003c/span\\u003e; Fig.\\u0026nbsp;\\u003cspan refid=\\\"Fig6\\\" class=\\\"InternalRef\\\"\\u003e6\\u003c/span\\u003e).\\u003c/p\\u003e \\u003cp\\u003eThe discrepancies presented by Villanueva-Olea et al. (\\u003cspan citationid=\\\"CR105\\\" class=\\\"CitationRef\\\"\\u003e2019\\u003c/span\\u003e) seem to be congruent with the background of Carboniferous Western Laurussian coasts. The interactions with meteoric waters and upwellings could have had a strong influence in Sierra Agua Verde δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO carbonate records during Mid-Carboniferous period.\\u003c/p\\u003e \\u003cp\\u003eDue to the Carboniferous paleoequatorial position of Sierra Agua Verde, covered by tropical waters and far from polar regions, the joint study of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e in limestones can help to understand the relationship between global and local environmental processes that affect the isotopic imprints on carbonated rocks. The strong relationship between early diagenesis and local environmental conditions could support the reconstruction of paleoceanographic and paleoclimatic conditions of Sierra Agua Verde paleoregion. Considering early diagenesis when interpreting δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO values can lead to a revised understanding of carbon and oxygen isotopic records. This study offers an approximation of how the environmental conditions were during the MPB in Sierra Agua Verde and how they were related to global climatology. Sonora outcrops have a great potential for Paleozoic geochemical studies and more investigation must be done in the region.\\u003c/p\\u003e\"},{\"header\":\"Declarations\",\"content\":\"\\u003cp\\u003eThe authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Pilar Navas-Parejo reports financial support was provided by PAPIIT-DGAPA-UNAM. Salvador Gutierrez Reyes reports financial support was provided by CONAHCyT. Pilar Navas-Parejo reports financial support was provided by CONAHCyT. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\\u003c/p\\u003e\\n\\u003cp\\u003e\\u003cstrong\\u003eACKNOWLEDGEMENTS\\u003c/strong\\u003e\\u003c/p\\u003e\\n\\u003cp\\u003eThe data involved in this work was obtained during the research work of SGR for his PhD thesis. In this way, we thank the Consejo Nacional de Humanidades, Ciencia y Tecnolog\\u0026iacute;a (CONAHCyT) for the postgraduate scholarship. We also thank the Posgrado en Ciencias de la Tierra, and the Estaci\\u0026oacute;n Regional del Noroeste, UNAM, for their support. We thank Francisco Otero, from the Laboratorio de Is\\u0026oacute;topos Estables (LANGEM, UNAM), and Korynthia Lopez, from the Laboratorio de An\\u0026aacute;lisis de Is\\u0026oacute;topos Estables (PCTY, UNAM), for the support in stable isotopic analysis. This work was supported by the CONAHCyT [grant numbers CF-7351]; and the UNAM [grant number UNAM-DGAPA-PAPIIT IN114923]. Finally, we want to give very special thanks to Fernando N\\u0026uacute;\\u0026ntilde;ez Useche for his great assistance with this work. His contributions in the interpretation of \\u0026delta;\\u0026sup1;\\u0026sup3;C and \\u0026delta;\\u003csup\\u003e18\\u003c/sup\\u003eO in limestones were essential to reconstruct the paleoenvironmental conditions concluded in this work.\\u0026nbsp;\\u003c/p\\u003e\\n\\u003cdiv style='margin-top:0in;margin-right:0in;margin-bottom:6.0pt;margin-left:0in;text-align:justify;line-height:200%;font-size:16px;font-family:\\\"Calibri\\\",sans-serif;'\\u003e\\n \\u003cp\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003e\\u003cstrong\\u003eAUTHOR CONTRIBUTIONS\\u003c/strong\\u003e\\u003c/span\\u003e\\u003c/p\\u003e\\n\\u003c/div\\u003e\\n\\u003cp style='margin-top:0in;margin-right:0in;margin-bottom:6.0pt;margin-left:0in;text-align:justify;line-height:200%;font-size:16px;font-family:\\\"Calibri\\\",sans-serif;'\\u003e\\u003cspan style='font-size:15px;line-height:200%;font-family:\\\"Times New Roman\\\",serif;'\\u003eAuthors:\\u003c/span\\u003e\\u003c/p\\u003e\\n\\u003cul style=\\\"list-style-type: disc;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003ehttps://orcid.org/0009-0008-9860-7885\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003eJuan Mois\\u0026eacute;s Casas Pe\\u0026ntilde;a\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003ehttps://orcid.org/0000-0003-3751-3945\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003eRafael Villanueva Olea\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003ehttps://orcid.org/0000-0002-8051-3150\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;color:black;'\\u003ehttps://orcid.org/0000-0002-1464-948X\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n\\u003c/ul\\u003e\\n\\u003cul style=\\\"list-style-type: disc;margin-left: -0.25in;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:15px;'\\u003eConceptualization\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New 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administration\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eResources\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eSoftware\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eSupervision\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eValidation\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eJuan Mois\\u0026eacute;s Casas Pe\\u0026ntilde;a\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eRafael Villanueva Olea\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eVisualization\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eJuan Mois\\u0026eacute;s Casas Pe\\u0026ntilde;a\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eRafael Villanueva Olea\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eWriting \\u0026ndash; original draft\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eSalvador Guti\\u0026eacute;rrez Reyes\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;'\\u003eWriting \\u0026ndash; review and editing\\u003c/span\\u003e\\n \\u003col style=\\\"list-style-type: circle;\\\"\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eJuan Mois\\u0026eacute;s Casas Pe\\u0026ntilde;a\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003eRafael Villanueva Olea\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003cli\\u003e\\u003cspan style='line-height:200%;font-family:\\\"Times New Roman\\\",serif;font-size:13px;color:black;'\\u003ePilar Navas-Parejo\\u003c/span\\u003e\\u003c/li\\u003e\\n \\u003c/ol\\u003e\\n \\u003c/li\\u003e\\n\\u003c/ul\\u003e\"},{\"header\":\"References\",\"content\":\"\\u003col\\u003e\\n\\u003cli\\u003eAlgeo, T. J., Berner, R. A., Maynard, J. B., \\u0026amp; Scheckler, S. E. (1995). Late Devonian oceanic anoxic events and biotic crisis: \\u0026ldquo;rooted\\u0026rsquo;\\u0026rsquo; in the evolution of vascular land plants?\\u0026rdquo; \\u003cem\\u003eGSA Today\\u003c/em\\u003e, \\u003cem\\u003e5\\u003c/em\\u003e(3).\\u003c/li\\u003e\\n\\u003cli\\u003eAllan, J. R., \\u0026amp; Matthews, R. K. (2009). Isotope Signatures Associated with Early Meteoric Diagenesis. In \\u003cem\\u003eCarbonate Diagenesis\\u003c/em\\u003e (pp. 197\\u0026ndash;217). Wiley Blackwell. https://doi.org/10.1002/9781444304510.ch16\\u003c/li\\u003e\\n\\u003cli\\u003eAl-Mojel, A., Dera, G., Razin, P., \\u0026amp; Le Nindre, Y. M. (2018). Carbon and oxygen isotope stratigraphy of Jurassic platform carbonates from Saudi Arabia: Implications for diagenesis, correlations and global paleoenvironmental changes. \\u003cem\\u003ePalaeogeography, Palaeoclimatology, Palaeoecology\\u003c/em\\u003e, \\u003cem\\u003e511\\u003c/em\\u003e, 388\\u0026ndash;402. https://doi.org/10.1016/j.palaeo.2018.09.005\\u003c/li\\u003e\\n\\u003cli\\u003eAretz, M., Herbig, H.-G., Wang, X. D., Gradstein, F. M., Agterberg, F. P., \\u0026amp; Ogg, J. G. (2020). The carboniferous period. In \\u003cem\\u003eGeologic time scale 2020\\u003c/em\\u003e (pp. 811\\u0026ndash;874). Elsevier.\\u003c/li\\u003e\\n\\u003cli\\u003eBabalola, L. O., Alqubalee, A. M., Kaminski, M. A., Abdullatif, O. M., \\u0026amp; Abouelresh, M. O. (2023). 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Onset of Late Palaeozoic glacio-eustasy and the evolving climates of low latitude areas: a synthesis of current understanding. \\u003cem\\u003eJournal of the Geological Society\\u003c/em\\u003e, \\u003cem\\u003e158\\u003c/em\\u003e(4), 579\\u0026ndash;582. https://doi.org/10.1144/jgs.158.4.579\\u003c/li\\u003e\\n\\u003c/ol\\u003e\"}],\"fulltextSource\":\"\",\"fullText\":\"\",\"funders\":[],\"hasAdminPriorityOnWorkflow\":false,\"hasManuscriptDocX\":true,\"hasOptedInToPreprint\":true,\"hasPassedJournalQc\":\"\",\"hasAnyPriority\":false,\"hideJournal\":true,\"highlight\":\"\",\"institution\":\"\",\"isAcceptedByJournal\":false,\"isAuthorSuppliedPdf\":false,\"isDeskRejected\":\"\",\"isHiddenFromSearch\":false,\"isInQc\":false,\"isInWorkflow\":false,\"isPdf\":false,\"isPdfUpToDate\":true,\"isWithdrawnOrRetracted\":false,\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true},\"keywords\":\"Mississippian, Pennsylvanian, Sonora, Geochemistry, Paleoclimatology\",\"lastPublishedDoi\":\"10.21203/rs.3.rs-6165627/v1\",\"lastPublishedDoiUrl\":\"https://doi.org/10.21203/rs.3.rs-6165627/v1\",\"license\":{\"name\":\"CC BY 4.0\",\"url\":\"https://creativecommons.org/licenses/by/4.0/\"},\"manuscriptAbstract\":\"\\u003cp\\u003eThe Paleozoic climate variations are preserved in δ\\u003csup\\u003e13\\u003c/sup\\u003eC and δ\\u003csup\\u003e18\\u003c/sup\\u003eO records from marine carbonate rocks. These records can be modified by diagenesis derived from the environmental processes of a particular region. The simultaneous evaluation of δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e can help to identify alterations and to improve environmental interpretations. The Late Paleozoic Ice Age began during the Carboniferous and coincided with the early stages of the Pangea assembly. The paleoceanographic and paleoclimatic changes affected the region of central Sonora, Mexico, at the westernmost embayment of the Rheic Ocean. To explore the relationship between local environmental processes and the early diagenesis imprint in the isotopic records, we estimate the δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values in 54 rock samples from Sonora. 38 samples were from the Sierra Agua Verde region, and 16 samples from the Cerro Las Rastras southern area. The early diagenetic imprint of the environmental variations suggests periods characterized by: (a) lower δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values which indicates heavy rains and/or riverine discharges; (b) higher δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e values associated with droughts; (c) lower δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values related to enhanced upwellings and/or riverine discharges; and (d) higher δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e values, reflecting a high productivity period. The δ\\u003csup\\u003e13\\u003c/sup\\u003eC\\u003csub\\u003ecarb\\u003c/sub\\u003e and δ\\u003csup\\u003e18\\u003c/sup\\u003eO\\u003csub\\u003ecarb\\u003c/sub\\u003e records from central Sonora rocks are consistent with those reported in the western USA, a region closely correlated with NW Mexico. The results of this study offer an approximation of how the environmental conditions were during the MPB in the westernmost Rheic Ocean area, and how they were related to global climatology.\\u003c/p\\u003e\",\"manuscriptTitle\":\"The carbonate-derived δ¹³C and δ¹⁸O records as proxies for Mid-Carboniferous climate in northwestern Mexico\",\"msid\":\"\",\"msnumber\":\"\",\"nonDraftVersions\":[{\"code\":1,\"date\":\"2025-05-19 08:44:06\",\"doi\":\"10.21203/rs.3.rs-6165627/v1\",\"editorialEvents\":[{\"type\":\"communityComments\",\"content\":0}],\"status\":\"published\",\"journal\":{\"display\":true,\"email\":\"info@researchsquare.com\",\"identity\":\"researchsquare\",\"isNatureJournal\":false,\"hasQc\":true,\"allowDirectSubmit\":true,\"externalIdentity\":\"\",\"sideBox\":\"\",\"snPcode\":\"\",\"submissionUrl\":\"/submission\",\"title\":\"Research Square\",\"twitterHandle\":\"researchsquare\",\"acdcEnabled\":true,\"dfaEnabled\":false,\"editorialSystem\":\"\",\"reportingPortfolio\":\"\",\"inReviewEnabled\":false,\"inReviewRevisionsEnabled\":true}}],\"origin\":\"\",\"ownerIdentity\":\"922a7f5e-d2c6-4d30-b7ed-244afc8ca172\",\"owner\":[],\"postedDate\":\"May 19th, 2025\",\"published\":true,\"recentEditorialEvents\":[],\"rejectedJournal\":[],\"revision\":\"\",\"amendment\":\"\",\"status\":\"posted\",\"subjectAreas\":[],\"tags\":[],\"updatedAt\":\"2025-07-01T11:21:25+00:00\",\"versionOfRecord\":[],\"versionCreatedAt\":\"2025-05-19 08:44:06\",\"video\":\"\",\"vorDoi\":\"\",\"vorDoiUrl\":\"\",\"workflowStages\":[]},\"version\":\"v1\",\"identity\":\"rs-6165627\",\"journalConfig\":\"researchsquare\"},\"__N_SSP\":true},\"page\":\"/article/[identity]/[[...version]]\",\"query\":{\"redirect\":\"/article/rs-6165627\",\"identity\":\"rs-6165627\",\"version\":[\"v1\"]},\"buildId\":\"8U1c8b4HqxoKbykW_rLl7\",\"isFallback\":false,\"isExperimentalCompile\":false,\"dynamicIds\":[84888],\"gssp\":true,\"scriptLoader\":[]}","source_license":"CC-BY-4.0","license_restricted":false}