Tonian glaciation in South China

Tonian glaciation in South China | 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 Article Tonian glaciation in South China Can Chen, Jiasheng Wang, Junchen Lu, Thomas Algeo, Simon Poulton, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7658226/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 Paleoclimatic conditions during the Tonian Period (~1000-720 Ma), preceding the Cryogenian Snowball Earth glaciations, remain ambiguous. While the apparent paucity of glacially influenced sedimentary rocks suggests a stable and dominantly ice-free climate during the late Tonian, several pre-Sturtian glacial deposits have been tentatively identified. To investigate climatic conditions leading up to the Cryogenian, we present glacial till depositions in Tonian from four outcrops in the Tongshan, South China, along with geochemical and geochronologic data from one of these sites, revealing significant regional climatic shifts during the Tonian period. This glacial till deposition is constrained older than 745.3 Ma from zircon age and is constrained in 792.1–773 Ma through stratigraphic correlation. In addition, another climatic cooling at ~750 Ma, although with no clear sedimentological evidence, is evidenced by decreased weathering proxy. This climatic cooling may have been correlated with the glaciolacustrine deposits of the Konnarock Formation in southwestern Virginia, USA. Our findings thus reveal the existence of at least two cold climate intervals during the late Tonian Period, thereby providing novel insights into the evolution of global climate conditions in advance of the Cryogenian Snowball Earth. Earth and environmental sciences/Solid Earth sciences/Geology/Precambrian geology Earth and environmental sciences/Climate sciences/Palaeoclimate Earth and environmental sciences/Solid Earth sciences/Geology Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction The Neoproterozoic Snowball Earth episodes represent some of the most extreme climatic events recorded in the geologic record, with two global glaciations characterized by icesheet expansion into low-latitude areas for millions of years, i.e., the Sturtian at ~717–661 Ma 1–3 and the Marinoan at ≤650–635 Ma 4,5 . However, paleoclimatic conditions during the preceding Tonian Period (1000–720 Ma) remain poorly known. Indeed, the general scarcity of glacially influenced sedimentary rocks potentially indicates a stable and predominantly ice-free climate in that period 6 . However, several pre-Sturtian glacial deposits have been tentatively identified, which, if verified, would document climatic cooling preceding the Cryogenian Snowball Earth 7–9 . Proposed pre-Sturtian glacial deposits include (1) the Kaigas Formation of the Gariep Belt on the Kalahari Craton 10 , (2) the Grand Conglomerate from the Kundelungu Basin on the Congo Craton 7 , (3) the Bayisi Diamictite on the Tarim Craton 8 , and (4) glaciolacustrine deposits of the Konnarock Formation in the southern Appalachians of Laurentia 9 . However, the significance of these formations as evidence of pre-Sturtian glaciation has been challenged on the basis of either age reassignment or re-interpretation of evidence for a glacial origin. For example, the glacial deposits of the Kalahari Craton that were previously assigned to the Kaigas Formation are now considered to belong to the syn-Sturtian (~717–661 Ma) Numees Formation, while pre-Numees strata were re-interpreted as part of a fan delta depositional system 11 . Similarly, the Grand Conglomerate of the Congo has been dated to <727 Ma and is thus coeval with Sturtian glaciation 1 . The poorly sorted conglomerates of the Bayisi Diamictite are thought to have formed within a volcanic rift 8 , and evidence for a glaciogenic origin is lacking. Finally, the Konnarock Formation in the southern Appalachians formed at low paleolatitudes and is regarded as a local high-altitude glaciolacustrine deposit 9 . Cratons at high paleolatitudes are more likely to record stratigraphic evidence of glaciation than those at lower paleolatitudes. Given the high-latitude location of the South China Block in the late Tonian 12–14 (Fig. 1A), the South China has considerable potential to record Tonian-aged glacial events, even if they were of lesser intensity than later Cryogenian Snowball Earth events. Here, we report sedimentological, geochronologic, and geochemical data from sedimentary rocks of the Liantuo Formation and the Dayaogu Formation in Tongshan area, South China. The U-Pb geochronology generating a depositional age from zircon grains in a tuff interbed, and a maximum depositional age from detrital zircon grains in a sandstone bed that immediately underlies an erosive unconformity at the top of the Liantuo Formation. The main goals of this study were to (1) identify whether there were glacial till deposits in the pre-Sturtian of the Tongshan section, (2) reconstruct patterns of climatic changes during the late Tonian in South China and their relationship to the documented glacial deposits, and (3) examine additional evidence from other regions that supports Tonian glacial events of possible global significance. Geological Setting The evolution of the Yangtze Block can be divided into 4 stages: ~1000-830 Ma pre-rifting, ~820-800 Ma early rifting, ~790-730 Ma peak rifting, and ~700-630 Ma late rifting 15 . The early and peak rifting stages record the initiation of deposition on the Yangtze Craton 16 . Metamorphosed to lightly-metamorphosed siliciclastic strata with widespread magmatism include the Banxi, Danzhou, Xiuning, Zhitang and Chengjiang formations (or groups), which unconformably overlie the basement beginning at ~820 Ma 17,18 . Under the combined influence of external subduction-accretion and internal rifting tectonic dynamics during the late Tonian, the western margin of the Yangtze Block experienced continuous subduction, while the northern margin was characterized by subduction-accretionary orogeny. Such tectonic settings had created mainly arc-related volcanic basins on the outer northern margins (Fig. 1B). In comparison, due to the tectonic activities gradually decreasing from north to south, the paleogeographic environment also changed regularly from fluvial-littoral facies in the north to shallow marine to bathyal facies in the south (Fig. 1B) 6 . The four study outcrops are located at the northern part of Tongshan County, Xianning City, Hubei Province (Fig. 1C). Outcrop 1 (GPS coordinates: 29°40′51″N, 114°29′25″E) displays, from bottom to top, the Tonian-aged Dayaogu Formation and Liantuo Formation, the Cryogenian-aged Datangpo Formation and Nantuo Formation, and the Ediacaran-aged Doushantuo Formation. Outcrop 2 (GPS coordinates: 29°40′32″N, 114°29′11″E), located approximately 500 meters southwest of Outcrop 1, exposes the Tonian-aged Xiaomuping Formation and the lower part of the Dayaogu Formation. By integrating the stratigraphic information from these two nearby outcrops, we constructed a complete stratigraphic sequence ranging from the uppermost Xiaomuping Formation to the lowermost Doushantuo Formation. This composite section is named as the Shimentang section, due to its proximity to the Shimentang reservoir. Outcrops 3 (GPS coordinates: 29°39′38″N, 114°27′34″E) and 4 (GPS coordinates: 29°39′45″N, 114°27′60″E) are situated ~3 km southwest of the Shimentang section and are seriously covered by Quaternary deposits. They expose the same stratigraphic sequence ranging from the Tonian-aged Xiaomuping Formation to the Cryogenian-aged Nantuo Formation. Each stratigraphic unit is notably thicker compared to those in the Shimentang section, and the sequence includes the Sturtian-aged Gucheng Formation, which is not present at Shimentang. Because these two outcrops are located on opposite sides of the Sidouzhu Reservoir, they are collectively referred to as the Sidouzhu Section. Results Lithological description Based on lithological characteristics, detailed measurements of the Shimentang section (Outcrops 1 and 2) have led to the identification of ten distinct stratigraphic units (Fig. 2). It should be noted that the descriptions for heights below 0 m are from Outcrop 2, whereas those above 0 m correspond to Outcrop 1. Unit 1 (–15.5 to –6 m): The underlying unit consists of gray to grayish-green slate. This unit is regarded as the Xiaomuping Formation. This slate is overlain by conglomerate of the base of the Dayaogu Formation (Fig. 2A). Unit 2 (–6 to 30 m): This unit is primarily composed of grayish-green to grayish-yellow silty mudstone, characterized by low-angle cross-stratification (Fig. 2B). Unit 3 (30 to 51 m): This unit is grayish-yellow to grayish-green, poorly sorted, clast-bearing silty claystone lacking bedding. It is interpreted as glacial till and will be described in detail in Discussion section. Unit 4 (51 to 66 m): This unit is dominated by grayish-green siltstone to grayish-yellow silty mudstone. Unit 5 (66 to 74 m): This unit is a grayish-green, rounded clast-bearing silty claystone that lacks distinct bedding. The clasts range in size from 0.2 to 2 cm and are poorly sorted (Fig. 2C). It unconformably overlies Unit 4. Units 2 to 4 are assigned to the Dayaogou Formation, whereas Unit 5 is considered the base of the Liantuo Formation. Unit 6 (74 to 125 m): This unit is dominated by grayish-green siltstone-sandstone interbedded with grayish-purple siltstone (Fig. 2D). The thickness of the differently colored siltstone layers ranges from less than 1 cm to ~10 cm. Horizontally laminated bedding is occasionally observed within these siltstones. In the middle of this unit is a grayish to off-white tuff layer at 112 m, which is easily distinguishable from the surrounding grayish-green siltstone/sandstone (Fig. 2D red dashed lines). The tuff layer is mainly composed of vitric fragments, crystal fragments, lithic fragments and clay matrix. Devitrification of vitric fragments during diagenesis has produced needle-like structures (Fig. 3A). Vesicular structures filled with felsic minerals are also present (Fig. 3B). In addition, crystal fragments are mainly composed of angular quartz (Fig. 3C and D, white arrows) and plagioclase (Fig. 3C and D, yellow arrows). Petrological evidence demonstrates a volcanic origin for this tuff. Unit 7 (125 to 183 m): The lowermost (125 to 135 m) and uppermost (174 to 183 m) of this units is a medium-bedded (~10 cm) gray coarse-grained quartz sandstone (Fig. 2E). The middle of this unit is dominated by dark-gray clay-rich mudstone interbedded with grayish-yellow siltstone showing graded bedding. Ripple cross-bedded siltstone is observed at 172 m, which may have been formed above the wave base (Fig. 2F, white dashed rectangle). Unit 8 (183 to 195 m): A Mn-enriched black shale unconformably overlies the sandstone (Fig. 2G), which is consistent with the characteristics of the Mn-enriched shale of the Datangpo Formation. Thus, the Sturtian-aged Gucheng diamictite is not present in the Northern Tongshan section. This observation is consistent with outcrops in the Three Gorges area, where both the Gucheng and Datangpo formations are missing 19 . Their local absence may be due to insufficient accommodation space resulting from sea-level fall. Unit 9 (195 to 230 m): Diamictite with subrounded to subangular clasts (0.5-15 cm diam.) of quartz, feldspar, granite, diorite and sandstone, representing the Marinoan-aged Nantuo Formation (Fig. 2H). Unit 10 (>230 m): Gray to dark gray medium-thick dolostone representing the cap dolostone of the lowermost Doushantuo Formation. The outcrop is severely covered in this unit (Fig. 2I). The stratigraphic sequence of the Sidouzhu section (outcrops 3 and 4) is broadly comparable to that of the Shimentang section, encompassing strata from the Tonian-aged Xiaomuping Formation to the Cryogenian-aged Nantuo Formation. Each formation in the Sidouzhu section is significantly thicker and may have undergone slight metamorphism 20 . Additionally, the sequence contains the Sturtian-aged Gucheng Formation, which is absent in the Shimentang section. Due to extensive Quaternary deposits obscuring the area, detailed stratigraphic units are not described. Instead, the lithological column is constructed based on a synthesis of two prior investigations conducted in this section 20,21 . Photographs documenting potential glacial till deposits were collected at all four outcrops (see Discussion). Zircon LA-ICP-MS U-Pb ages The results of LA-ICP-MS U-Pb dating of zircons in the tuff (112 m, n = 120) and sandstone (182 m, n = 120) samples are presented in Supplementary Tables 1 and 2. In the tuff sample, the zircon grains are 90–150 μm long and 35–50 μm wide (Fig. 4A, inset photograph), and in the sandstone sample they are relatively irregular and spherical-elliptical with diameters in the range of 20–150 μm (Fig. 4C, rounded inset), consistent with abrasion during transport. All zircon grains are transparent to pale yellow in color and display a euhedral to subhedral shape, with clear oscillatory growth zones under cathodoluminescence (Fig. 4E-F). In addition, nearly all grains (233 of 240) yield Th/U > 0.4, consistent with magmatic origins 22 . Zircon grains from the tuff sample have Th concentrations ranging from 40–1090 ppm and U contents ranging from 45–442 ppm. Of 120 grains, 91 exhibit a concordance of >90%. The zircon U-Pb ages range from 618–854 Ma and can be divided into three groups (Fig. 4A). The Group 1 contains 7 grains with a dispersed age distribution (618–694 Ma) that generally deviates from the line of concordance. The relatively concentrated ages within this group yield a weighted mean 206 Pb/ 238 U age of 674.0 ± 5.2 Ma, which is associated with an anomalously high MSWD value of 27 ( n = 6), suggesting dispersion possibly due to Pb loss. Additionally, the age of 674.0 ± 5.2 Ma corresponds to the Marinoan Glaciation, represented by the overlying Nantuo Formation, and is significantly younger than the known depositional age of the Liantuo Formation (ca. 780–714 Ma 13,19,23 ). Therefore, zircon grains from Group 1 cannot be interpreted as representing the depositional age of this tuff layer. The Group 2 comprises 74 grains that yield a weighted mean 206 Pb/ 238 U age of 747.2 ± 1.9 Ma (MSWD = 0.87, n = 74) (Fig. 4B). The third group contains 10 grains with ages of 769–854 Ma, which can be linked to magmatic episodes in South China at 780–745 Ma and 820–800 Ma 16 . Since the ages of the zircons of Groups 1 and 3 can be attributed to Pb loss and older magmatic activity, respectively, the U-Pb age cluster of Group 2 (747.2 ± 1.9 Ma) represents the best estimate of the age of tuff eruption and deposition. In the sandstone sample, 111 of 120 zircon grains exhibit a concordance of >90% (Fig. 4C). The youngest detrital zircon grains in a siliciclastic rock sample are commonly used to interpret its maximum depositional age 24 . In this sample, the youngest group of U-Pb ages, consisting of 89 zircon grains, ranges from 987 to 715 Ma (Fig. 4C, rectangular inset), and the youngest cluster of ages yields a maximum depositional age of 722.9 ± 4.5 Ma (MSWD = 0.77, n = 12) (Fig. 4D). Thus, the age of the uppermost Liantuo Formation in the Northern Tongshan section is interpreted to be younger than 722.9 ± 4.5 Ma, which is close to the onset of the Sturtian Snowball glaciation at ca. 717 Ma 2,25 . Weathering proxies Chemical Index of Alteration (CIA) values are listed in Supplementary Table 3. The study interval exhibits three major declines in weathering proxies, in the lower (15.15 m), middle (114.00 m) and uppermost (198.95 m) parts of the section (Fig. 5). CIA values decrease from 71 to 67 at 15.15 m and increase to 78 at 53.25 m. Above this level, CIA values gradually decrease to 62 at 114.0 m and then increase to 74 at 155.3 m. In the uppermost interval (to 198.95 m), CIA values decrease once more, from 74 to 67. Discussion Characterization of glacial deposition The grayish-yellow to grayish-green, poorly sorted, clast-bearing silty claystone observed in all four outcrops of the Dayaogu Formation is interpreted as glacial till (Fig. 6). The clasts range in diameter from 0.2 mm to ~30 cm (Fig. 6A and I yellow arrow), and consist of quartz, feldspar, granite, and diorite (Fig. 6C and L). Clast shapes include subrounded prolate shape (Fig. 6B), rounded shape (Fig. 6C), oblate shape (Fig. 6F), and subrounded/subangular shape with poor sorting (Fig. 6D, K, and L). In particular, scratches that may have been formed from glacier movement can be found in oblate-shape clasts (Fig. 6F yellow arrows). These characteristics collectively provide a robust set of criteria for identifying the deposit as a glacial till, effectively distinguishing it from other diamictites of similar appearance but different origin, such as those formed in fluvial and debris flow. Fluvial conglomerates are characterized by moderate to good sorting and a high degree of clast roundness due to prolonged abrasion during bedload transport (e.g., Fig. 2C). They typically exhibit clast imbrication, where elongated pebbles are oriented with their flat planes dipping upstream, and are supported by a well-sorted sandy matrix 28 . In contrast, the Dayaogu deposit shows extremely poor sorting with a wide, unstructured grain-size distribution and a clay-silt matrix, which is inconsistent with the winnowing and sorting action of consistent hydraulic flow. The presence of both well-rounded and subangular clasts is a key indicator (e.g., Fig. 6I-L); the rounded clasts are likely reworked from pre-existing deposits and incorporated into the ice without significant further abrasion, a common feature in tills. While debris flow deposits (lahars, mudflows) can also be poorly sorted and matrix-supported. The most definitive differentiating feature is the presence of glacial striations (scratches) observed on the oblate clasts. These parallel, linear grooves are formed by subglacial abrasion as debris-laden ice grinds over a substrate. This is a hallmark of glacial transport virtually never replicated in the high-fluid-content, short-duration shear environment of a debris flow. In addition, debris flow deposits are typically of limited lateral extent; in contrast, this particular diamictite unit may has been observed in numerous sections across the Yangtze Block (see Discussion of Figure 8). The forcible embedding of clasts is evident in photomicrographs. Edge-to-edge crushing ( e-e ) microstructures are found in samples at 32 m (Fig. 7A, black dashed rectangles). The e-e microstructures developed at the earliest stages of subglacial till formation as soon as the sediment experienced strain 29 and can be easily destroyed by development of other structures. Thus, the existence of e-e microstructures for this sample may indicate limited reworking by subsequent glacial outwash or flowing water. Grain stacks ( gst ) are observed in most samples of this unit as linear arrangements of grains that form as two sets of conjugate structures, likely indicative of simple shear deformation (Fig. 7D-F, blue dashed lines). Grain stacks evolved after e-e and are an important kinematic marker of till deformation 29 . Rotation structures ( rt ) are also common in this unit (Fig. 7, orange arrows). This microstructure is often observed in fine-grained subglacial tills with relatively high clay content (>20% 30 ), reflecting plastic flow during subglacial deformation. Because gst are commonly twisted around rt of larger clasts (Fig. 7D and E), the rt is interpreted to have formed later than gst . Another feature typical of subglacial tills is the presence of multiple domains ( dom ) of often slightly different or in some cases very different lithofacies units that have all been incorporated into the subglacial till (Fig. 7F, black lines) 31 . The domains are found at 50 m and are likely formed due to previously deposited sediments being incorporated into the subglacial till and subsequently moving within a mobile soft-sediment subglacial bed prior to final emplacement 31 . All macroscopic and microscopic characteristics of the clasts are consistent with glacial till deposition. Depositional ages and stratigraphic correlation of Tonian Glacial deposits The 747.2 ± 1.9 Ma age of the tuff at 112 m indicates that the glacial deposits in the Dayonggu Formation of the Shimentang section are almost certainly of late Tonian age. Tuffs dated to approximately 750 Ma have also been identified in the middle of the overlying Liantuo Formation from several nearby outcrops in Hubei Province, suggesting that the same tuff layer may be present regionally (Fig. 8A-D; pink dashed line). In the Shennongjia area, a fine-bedded tuff yielded a youngest population of zircon grains (20 of 35) with a concordant age of 752 ± 6.5 Ma 28 (Fig. 8A). In the Changyang section, a tuff yielded a youngest group of zircon grains (21 of 35) with a concordant age of 751.5 ± 6.3 Ma 32 (Fig. 8B). In the Three Gorges area, tuffs from the middle to upper parts of the Liantuo Formation yielded a youngest zircon age cluster of 748 ± 12 Ma 33 (Fig. 8C). These chronological studies confirm that the Liantuo Formation was deposited during the late Tonian Period. The youngest cluster of ages from detrital zircons in the uppermost beds of the Liantuo Formation (722.9 ± 4.5 Ma) is similar to those of tuffs from the top of the Liantuo Formation (Fig. 8A and C), suggesting the maximum depositional age of this sandstone is close to its true depositional age. The absence of the Sturtian-aged Gucheng Formation may be attributed to insufficient accommodation space resulting from a glacio-eustatic sea-level fall during the early Cryogenian. Similar stratigraphic relationships have also been observed in other sections, where the Liantuo Formation is unconformably overlain by the Marinoan-aged Nantuo Formation (e.g., Fig. 8C). Given a magmatic zircon age of 660.1 ± 3.6 Ma for the basal Datangpo Formation (Fig. 8B), this unconformity represents a ~60-Myr-long hiatus in the Shimentang section. In the nearby Sidouzhu section, the depositional age of these glacial deposits has been further constrained to between 823 Ma and 760.5 Ma (Fig. 8E) based on a detrital zircon age of 816 ± 7 Ma from the base of the Dayaogu Formation 20 and a magmatic zircon age of 764.1 ± 3.6 Ma from the base of the Liantuo Formation 32 . This suggests a potential correlation between these glacial deposits and the controversial Chang’an Formation, which was proposed to be associated with the so-called “Kaigas Glaciation” 34,35 . Although the concept of the “Kaigas Glaciation” has recently been challenged by Pu et al. 11 , zircon ages obtained from the base of this diamictite unit support the existence of pre-Sturtian glacial deposits in South China (Fig. 8F–G) and provide tighter age constraints for this glacial till sequence at 792.1–773 Ma. In addition, these deposits exhibit a wide spatial distribution, extending from nearshore to shallow marine environments (Fig. 1B). Paleoclimate in the Shimentang section and global evidence for Pre-Sturtian Glaciations The chemical index of alteration has been applied as a proxy for paleoclimatic change in many studies 37–39 . However, it is imperative to assess influences related to sedimentary provenance, grain size, sediment recycling, and K-metasomatism in order to avoid potential misinterpretations of CIA signals 27,40,41 . Changes in protolith composition can influence the chemical composition of the weathering product 40 , so it is first necessary to evaluate the protolith in order to draw paleoclimate inferences based on variations in weathering proxy data. Ternary A-CN-K (i.e., molar Al 2 O 3 -(Na 2 O+CaO*)-K 2 O) diagrams can permit inferences about protolith composition 41 . In the present study section, three parallel weathering trends are observed, with one trend (Trend 1, pink dashed arrow; Fig. 5A) showing relatively greater weathering intensity than the other two trends (Trends 2 and 3, yellow and blue dashed arrows; Fig. 5A). The weathering trends 2 and 3 can be extended backward to a point that represents the average composition of the Yangtze Craton 26 , suggesting derivation from a mixture of regionally weathered material, whereas Trend 1 shows a markedly more mafic protolith, suggesting more localized weathering sources. Although the exact cause of this shift cannot be determined, several possible influences can be identified: (1) changes in sea level or glacial cycles resulting in submergence or exposure of terrigenous source areas; (2) changes in river drainage systems (e.g., the presence of fluvial deposits at the Liantuo Formation may indicate development of a new estuary); and/or (3) major tectonic movements during rifting of the Yangtze Craton, exposing new rock units to weathering. Hydrodynamic sorting segregates detrital minerals according to their size, shape and density, leading to geochemical differentiation in sediments 41 . Therefore, weathering indices based on sediment chemistry may reflect not only weathering intensity also hydraulic changes during sediment transport and deposition. Grain size, as a result of hydrodynamic sorting, can be represented by molar Al 2 O 3 /SiO 2 ratios 42 . However, only a weak correlation is apparent between Al 2 O 3 /SiO 2 and CIA ( r = +0.14, n = 28, p 80 m), but that lower energy conditions of deposition of the former resulted in the preferential accumulation of fines, shifting Trend 1 toward higher Al 2 O 3 compositions relative to the other trends. Given the tentativeness of this inference, no correction procedure was applied. A WIP (Weathering Index 43 ) vs. CIA diagram can be used to evaluate whether samples have undergone significant sedimentary recycling. The relationship between CIA and WIP is linear for first-cycle muds and sands 27 . However, recycled samples display quartz dilution produced by physical processes in chemical-weathering-limited conditions. The effect of quartz dilution is most easily detected in more arid regions, where recycling is indicated by low WIP despite low CIA (Fig. 5C, dashed line). The proximity of all present study samples to the first-cycle weathering line suggests a minimal influence from sedimentary recycling (Fig. 5C). Furthermore, the relatively strong covariation of Zr/Sc and Th/Sc in most samples (30 of 32) also indicates that these samples likely originated from first-cycle weathering ( r = +0.83, n = 31, p < 0.001, Fig. 5D). This is because first-cycle sedimentary deposits exhibit strong positive covariation of Zr/Sc and Th/Sc and a compositional variation trend reflective of the source rock. Recycled sediments, in contrast, exhibit greater variation in Zr/Sc than Th/Sc owing to preferential preservation of zircons 44 . K-metasomatism results from the alteration of rocks by hydrothermal or magmatic fluids, a process that typically introduces excess K 2 O and leads to formation of secondary K-bearing minerals 45 or replacement of plagioclase by K-feldspar 46 . Metasomatic introduction of K 2 O lowers measured CIA values, making quantitative corrections for K-metasomatic effects necessary to recover primary weathering signals. The most widely used method is based on the concept of an “ideal weathering trend” that aligns parallel to the A-CN axis 47 . However, given the observed substantial variability of actual weathering trends in modern soil profiles, Algeo et al. 41 demonstrated that reliance on an “ideal weathering trend” may result in unwarranted inferences regarding K-metasomatism and inaccurate correction of CIA values. They further argued that highly aligned data arrays in A-CN-K space generally represent original weathering trends. In this study, although a low-temperature hydrothermal deposit is present in northern Jiangxi Province (~300 km east of Tongshan 48 ), we infer that the present study samples were unaffected (or minimally affected) by K-metasomatism for the following reasons: (1) the A-CN-K relations of the study samples reveal three separate weathering trends, each developed within a discrete stratigraphic interval of the study section, that are aligned and quasi-parallel to each other, extending from the feldspar line to the illite pole; (2) none of these weathering trends shows a significant deviation towards the K apex; and (3) Eu/Eu* values range from 0.74 to 1.41 (Supplementary Table 4, mean 1.07 ± 0.16). Therefore, no correction procedure was applied for K-metasomatic effects. The CIA profile suggests that two intervals were deposited under relatively cooler and/or more arid climatic conditions (Fig. 5A). The older glacial event interval (GE-I) shows distinct characteristics that support glacial deposition and constrained to 792.1–773 Ma according to stratigraphic correlation. Given the high paleolatitude of the South China Block at ~780 Ma (cf. Fig. 1A), these ice-contact deposits likely reflect the existence of glaciers and/or icesheets in the Northern Hemisphere polar region at that time. The younger glacial event interval (GE-II), however, shows no clear sedimentological evidence for ice-contact deposition. Here, the age of 747.2 ± 1.9 Ma from a tuff interbed supports broad temporal equivalence with cool climatic conditions recorded in the ca. 750 Ma Konnarock Formation of the southern Appalachians, Laurentia 9 . These GEs can also be evident from CIA across disparate paleocontinental settings, with decreased CIA not only in South China 28,49,50 but also in the Grand Canyon in North America 51 . In addition, the recent observation of petrographic fingerprints of ikaite from North America—a mineral that typically forms in near-freezing sedimentary environments—in late Tonian strata (780–730 Ma) was interpreted as evidence that low-latitude shallow marine environments were cold prior to the Cryogenian Period 52,53 . Together, these transcontinental records provide relatively robust evidence for pre-Sturtian glaciations. Conclusion We investigated U-Pb geochronology and paleoweathering for a Tonian outcrop section at Tongshan, South China. Based on sedimentological and geochemical evidence, we propose the existence of two relatively colder climatic intervals: GE-I at ~780 Ma and GE-II at ~750 Ma. The earlier colder interval was accompanied by the deposition of glacial till on the South China Block. We suggest that the higher paleolatitude of the South China Block enabled the proximal development of glaciers (and possibly icesheets) at GE-I. Conversely, no sedimentological evidence for glacial deposition has been recorded for the GE-II in South China, but this interval coincides with low latitude (high altitude) glaciolacustrine strata in Laurentia. Our study thus reveals multiple intervals of global cooling during the Tonian, thereby adding important new constraints for the accurate calibration of global Earth System models that aim to reconstruct climatic conditions in advance of the Sturtian Snowball Earth. Methods Zircon U-Pb geochronology In the Shimentang section, a tuff in the middle of the Liantuo Formation (at 112 m) and a sandstone bed near its top (at 182 m) were sampled for zircon U-Pb dating. Approximately 3.3 kg of volcanic tuff and 2.5 kg of sandstone were powdered to 60 mesh and processed to recover zircon concentrates using conventional magnetic and density separation techniques in a clean lab at the State Key Laboratory of Geomicrobiology and Environmental Geology, China University of Geosciences-Wuhan. Zircon grains were handpicked from each sample under a stereoscopic microscope, mounted onto 2.54-cm epoxy disks, and polished to expose an interior cross-section of each grain. All zircon grains were documented with cathodoluminescence images to observe their internal structure and to identify any detrital or inherited components. An Analytical Scanning Electron Microscope (JSM-IT100) connected to a GATAN MINICL system was used to generate cathodoluminescence images. The imaging conditions included a 10.0–13.0 kV electric field and an 80–85 μA current through a tungsten filament. Measurements of U, Th, Pb and other trace elements were performed by LA-ICP-MS at Wuhan Sample Solution Analytical Technology Co. Laser sampling was conducted using a GeolasPro laser ablation system that consists of a COMPexPro 102 ArF excimer laser and a MicroLas optical system. An Agilent 7700e ICP-MS instrument was used to acquire ion-signal intensities. The laser was operated at a wavelength of 193 nm and maximum energy of 200 mJ. The laser spot size and frequency were set to 32 μm and 5 Hz, respectively. Helium was used as a carrier gas and argon was used as the make-up gas, which was mixed with the carrier gas via a T-connector before entering the ICP. A “wire” signal smoothing device was included in the laser ablation system 54 . Each analysis included a background acquisition of approximately 20 s (gas blank), followed by 50 s of data acquisition from the sample. Detailed operating conditions for the laser ablation system and the ICP-MS instrument, as well as the data reduction method, followed those of Zong et al. 55 . An Excel-based software, ICPMSDataCal 10.9, was used to perform off-line selection and integration of background and analyzed signals, time-drift correction and quantitative calibration for trace element analysis and U-Pb dating 56 . To ensure the reliability of the data, zircon 91500, GJ-1, Ple, Tanz, and SRM 610 were used as external standards for U-Pb dating and trace element calibration, and the zircon GJ-1 was used as a second standard to monitor data quality. The 91500 standard was analyzed twice for every 7 unknowns. Concordia diagrams for U-Pb isotopic ratios and weighted mean calculations were made using Isoplot 3.0. Because old zircons can contain large amounts of radiogenic Pb, 207 Pb/ 206 Pb ages were adopted for zircons with ages >1000 Ma, and 206 Pb/ 238 U ages were adopted for zircons with ages <1000 Ma 57 . The age data and Th/U ratios are listed in Supplementary Tables 1 and 2. Major element analysis and weathering proxies Major element concentration data for 28 bulk samples (avoiding large clasts in till samples) were analyzed on a Zsx Primus II wavelength dispersive X-ray fluorescence spectrometer at the Wuhan Sample Solution Analytical Technology Co. These data were calibrated using national standard materials GBW07101-14, GBW07401-08 and GBW07302-12, and corrected by the theoretical α coefficient method 58 , yielding relative standard deviations of less than 2% for all elements of interest. The chemical index of alteration (CIA) was applied to evaluate variation in paleoweathering intensity 37,41 : CIA = molar [(Al 2 O 3 ) / (Al 2 O 3 + CaO* + Na 2 O + K 2 O)] × 100, where CaO* represents CaO in silicate minerals. Here, CaO* was corrected for Ca associated with phosphate (CaO* = molar CaO – molar P 2 O 5 × 10/3). If the calculated CaO* content was greater than Na 2 O, then Na 2 O was used in place of CaO* 44 . This correction is applicable exclusively to materials with relatively felsic protoliths, i.e., >60 wt% SiO 2 41 , a condition met by all of the present study samples (Supplementary Table 3). In addition, in order to evaluate any potential influence and multi-cyclic weathering, we calculated the Weathering Index (WIP 43 ), expressed as: WIP = molar (CaO*/0.7 + 2Na 2 O/0.35 + 2K 2 O corr /0.25 + MgO/0.9) × 100. Trace and rare earth element (REE) analysis A total of 32 bulk samples (avoiding large clasts in till samples) were analyzed on an Agilent 7700e ICP-MS at the Wuhan Sample Solution Analytical Technology Co. One mL of HNO 3 and 1 mL of HF were slowly added to 50 mg of sample powder (200 mesh) in a Teflon bomb, and the mixture was heated to 190 ℃ in an oven for >24 h (n.b., all utilized acids were high-purity laboratory-grade). After cooling, the Teflon bomb was opened and placed on a hotplate at 140 ℃ and evaporated to incipient dryness, and then 1 mL of HNO 3 was added and evaporated to dryness again. One mL of HNO 3 , 1 mL of MQ water, and 1 mL of an internal standard solution comprising 1 ppm In were added, and the Teflon bomb was resealed and placed in the oven at 190 ℃ for >12 h. The final solutions were transferred to polyethylene bottles and diluted to 100 g via addition of 2% HNO 3 prior to ICP-MS analysis. The international rock standards RGM-2, GSR-3 and JA-2 were used to monitor analytical accuracy. Analytical precision was better than ±5% for all elements based on international rock standards and replicate extractions. The results were listed in Supplementary Table 4, where Eu/Eu* = Eu N /(Sm N 2 ×Tb N ) 1/3 and the subscript N represents normalization to PAAS (Post-Archean Australian Shale). Declarations Acknowledgments This research was supported by the National Science and Technology Major Project of China (2025ZD1008901) and National Natural Science Foundation of China (42276068, 42302215, and 42472374). References Rooney, AD, Strauss, JV, Brandon, AD & Macdonald, FA A Cryogenian chronology: Two long-lasting synchronous Neoproterozoic glaciations. Geology 43 , 459–462 (2015). Rooney, AD, Yang, C, Condon, DJ, Zhu, M & Macdonald, FA U-Pb and Re-Os geochronology tracks stratigraphic condensation in the Sturtian snowball Earth aftermath. Geology 48 , 625–629 (2020). Ma, X, Wang, J, Wang, Z, Algeo, TJ, Chen, C, Cen, Y, Yin, Q-Z, Huang, C, Xu, L, Huang, C & Chen, D Geochronological constraints on Cryogenian ice ages: Zircon U-Pb ages from a shelf section in South China. Glob. Planet. Change 222 , 104071, https//doi.org/10.1016/j.gloplacha.2023.104071 (2023). Hoffmann, K-H, Condon, DJ, Bowring, SA & Crowley, JL U-Pb zircon date from the Neoproterozoic Ghaub Formation Namibia: Constraints on Marinoan glaciation. Geology 32 , 817–820 (2004). Condon, D, Zhu, M, Bowring, S, Wang, W, Yang, A & Jin, Y U-Pb ages from the Neoproterozoic Doushantuo Formation, China. Science 308 , 95–98 (2005). Dong, Y, Hui, B, Sun, S, Sun, J, Zang, R, Zhang, B, Luo, Q, Chong, F, Yu, K, Fan, M, Li, Y, Li, Y, Zhu, X, Dai, Q & Zuo, Z The links between Neoproterozoic tectonics, paleoenvironment and Cambrian explosion in the Yangtze Block, China. Earth Sci. Rev. 248 , doi.org/10.1016/j.earscirev.2023.104638 (2024). Key, RM, Liyungu, AK, Njamu, FM, Somwe, V, Banda, J, Mosley, PN & Armstrong, RA The western arm of the Lufilian Arc in NW Zambia and its potential for copper mineralization. J. Afr. Earth Sci. 33 , 503–528 (2001). Xu, B, Xiao, S, Zou, H, Chen, Y, Li, ZX, Song, B, Liu, D, Zhou, C & Yuan, X SHRIMP zircon U-Pb age constraints on Neoproterozoic Quruqtagh diamicities in NW China. Precambrian Res. 168 , 247–258 (2009). MacLennan, SA, Eddy, MP, Merschat, AJ, Mehra, A, Crockford, P, Maloof, AC, Southworth, CS & Schoene, B Geologic evidence for an icehouse Earth before the Sturtian global glaciation. Sci. Adv. 6 , eaay6647 (2020). Frimmel, HE Neoproterozoic Gariep Orogen. in The Geology of Namibia : Volume 2 , Neoproterozoic to Lower Palaeozoic (ed. Miller, RM) 14.1–14.39 (2008). Pu, JP, Macdonald, FA, Smith, EF, Ramezani, J & Swanson-Hysell, N Tonian basins record rifting of Kalahari from Rodinia and no evidence of a pre-Sturtian Kaigas glaciation. Earth Planet. Sci. Lett. 624 , https//doi.org/10.1016/j.epsl.2023.118472 (2023). Merdith, AS, Collins, AS, Williams, SE, Pisarevsky, S, Foden, JD, Archibald, DB, Blades, ML, Alessio, BL, Armistead, S, Plavsa, D, Clark, C & Müller, RD A full-plate global reconstruction of the Neoproterozoic. Gondwana Res. 50 , 84–134, https://doi.org/10.1016/j.gr.2017.04.001 (2017). Park, Y, Swanson-Hysell, NL, Xian, H, Zhang, S, Condon, DJ, Fu, H & Macdonald, FA A consistently high-latitude South China from 820 to 780 Ma: implications for exclusion from Rodinia and the feasibility of large-scale true polar wander. J. Geophys. Res. Solid Earth 126 , https//doi.org/10.1029/2020jb021541 (2021). Chang, L, Zhang, S, Li, H, Xian, H, Wu, H & Yang, T New paleomagnetic insights into the Neoproterozoic connection between South China and India and their position in Rodinia. Geophys. Res. Lett. 49 , https//doi.org/10.1029/2022gl098348 (2022). Li, S, Li, X, Wang, G, Liu, Y, Wang, Z, Wang, T, Cao, X, Guo, X, Somerville, I, Li, Y, Zhou, J, Dai, L, Jiang, S, Zhao, H, Wang, Y, Wang, G & Yu, S Global Meso-Neoproterozoic plate reconstruction and formation mechanism for Precambrian basins: constraints from three cratons in China. Earth Sci. Rev. 198 , 102946. doi.org/10.1016/j.earscirev.2019.102946 (2019) Li, Z Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correlations with other continents: evidence for a mantle superplume that broke up Rodinia. Precambrian Res. 122 , 85–109 (2003). Song, G, Wang, X, Shi, X & Jiang, G New U-Pb age constraints on the upper Banxi Group and synchrony of the Sturtian glaciation in South China. Geosci. Front. 8 , 1161–1173 (2017). Xu, Y, Zhang, K, He, W, Yu, Y, Kou, X, Song, B, Luo, M, Wang, L, Ma, Z & Yang, F Tonian tectonic-strata regions and geological significance in China. Acta Geol. Sin. Engl. Edn. 94 , 914–941 (2020) Lan, Z, Li, XH, Zhu, M, Zhang, Q & Li, Q-L Revisiting the Liantuo Formation in Yangtze Block, South China: SIMS U-Pb zircon age constraints and regional and global significance. Precambrian Res. 263 , 123–141 (2015). He, Y-Y, Niu, Z-J, Song, F & Yang, W-Q Geological characteristics and stratigraphic correlation of the Neoproterozoic Dayaogu Formation of the Lengjiaxi Group in Southern Hubei Province. J. Stratigr. 41 , 195–208 (2017) (in Chinese with English abstract). Song, F, Niu, Z-J, Liu, H, He, Y-Y & Yang, W-Q Stratigraphic sequence and contact relationship of the Nanhua system in South-Eastern Hubei Province: a key to the stratigraphic correlation between the inner Yangtze region and the south-eastern basin. J. Stratigr. 40 , 251–260 (2016) (in Chinese with English abstract). Rubatto, D Zircon trace element geochemistry: partitioning with garnet and the link between U-Pb ages and metamorphism. Chem. Geol. 184 , 123–128 (2002). Ning, K, Deng, Q, Cui, X, Wang, Z, Ren, G & Yang, Q Zircon U-Pb age and stratigraphic significance of the tuff from the lowermost Liantuo Formation in the Dahongshan area of the northern Yangtze Block. Geol. Bull. China 43 , 363–375 (2024) (in Chinese with English abstract). Ma, X, Wang, J, Algeo, TJ, Wang, Z, Cen, Y, Chen, C, Chen, D, Lu, J & Yang, Y U-Pb dating of detrital zircons from the Datangpo Formation, South China: Implications for Sturtian deglaciation age and Nanhua stratal provenance. Palaeogeogr. Palaeoclimatol. Palaeoecol. 617 , 111494, https//doi.org/10.1016/j.palaeo.2023.111494 (2023). Lan, Z, Huyskens, MH, Lu, K, Li, X-H, Zhang, G, Lu, D & Yin, Q-Z Toward refining the onset age of Sturtian glaciation in South China. Precambrian Res. 338 , doi.org/10.1016/j.precamres.2019.105555 (2020). Gao, S, Luo, TC, Zhang, BR, Zhang, HF, Han, YW, Zhao, ZD & Hu, YK Chemical composition of the continental crust as revealed by studies in East China. Geochim. Cosmochim. Acta 62 , 1959–1975 (1998). Garzanti, E, Padoan, M, Setti, M, Najman, Y, Peruta, L & Villa, IM Weathering geochemistry and Sr-Nd fingerprints of equatorial upper Nile and Congo muds. Geochem. Geophys. Geosyst. 14 , 292–316 (2013). Wang, Y, Kuang, H, Liu, Y, Zhao, F, Peng, N, Chen, X, Qi, K, Liu, H, Wang, Z, Zhong, Q & Chen, J Sedimentary evolution from greenhouse to icehouse of Neoproterozoic and age constraints in the northern Yangtze Craton. Glob. Planet. Change 227 , https//doi.org/10.1016/j.gloplacha.2023.104179 (2023). Menzies, J, van der Meer, JJM & Ravier, E A kinematic unifying theory of microstructures in subglacial tills. Sediment. Geol. 344 , 57–70, https//doi.org/10.1016/j.sedgeo.2016.03.024 (2016). Tembe, S, Lockner, DA & Wong, T-F Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite. J. Geophys. Res. 115 , B03416 (2010). Menzies, J & Ellwanger, D Insights into subglacial processes inferred from the micromorphological analyses of complex diamicton stratigraphy near Illmensee-Lichtenegg, Hochsten, Germany. Boreas 40 , 271–288, https//doi.org/10.1111/j.1502-3885.2010.00194.x (2010). Wang, Y, Kuang, H, Liu, Y, Zhao, F, Peng, N, Chen, X, Qi, K, Liu, H & Dong, G Chronological framework and sedimentary evolution process of the Neoproterozoic Liantuo Formation in the Yangtze Craton. Acta Geol. Sin. 97 , 3922–3952 (2023) (in Chinese with English abstract). Ma, G, Li, H & Zhang, Z An investigation of the age limits of the Sinian System in South China. Bull. Yichang Inst. Geol. Miner. Resour. Chin. Acad. Geol. Sci. 6–34 (1984) (in Chinese with English abstract). Gao, LZ, Lu, JP, Ding, XZ, Wang, HR, Liu, YX & Li, J Zircon U-Pb dating of Neoproterozoic tuff in South Guangxi and its implications for stratigraphic correlation. Geol. China 40 , 1443–1452 (2013) (in Chinese with English abstract). Yin, CY & Gao, LZ Definition, time limit and stratigraphic subdivision of the Nanhuan System in China. J. Stratigr. 37 , 534–541 (2013) (in Chinese with English abstract). Zhang, S, Jiang, G, Dong, J, Han, Y & Wu, H New SHRIMP U-Pb age from the Wuqiangxi Formation of Banxi Group: Implications for rifting and stratigraphic erosion associated with the early Cryogenian (Sturtian) glaciation in South China. Sci. China Ser. D Earth Sci. 51 , 1537–1544, doi.org/10.1007/s11430-008-0119-z (2008). Nesbitt, HW & Young, GM Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 299 , 715–717 (1982). Chen, C, Wang, J, Wang, Z, Peng, Y, Chen, X, Ma, X, Cen, Y, Zhao, J & Zhou, P Variation of chemical index of alteration (CIA) in the Ediacaran Doushantuo Formation and its environmental implications. Precambrian Res. 347 , 105829 (2020). Chen, C, Wang, J, Chen, X, Algeo, TJ, Wang, Z, Yang, W & Song, Q Productivity and redox influences on the late Ordovician ‘Katian Extinction’ and ‘early Silurian Recovery’. Palaeogeogr. Palaeoclimatol. Palaeoecol. 642 . doi.org/10.1016/j.palaeo.2024.112176. (2024) Price, JR & Velbel, MA Chemical weathering indices applied to weathering profiles developed on heterogeneous felsic metamorphic parent rocks. Chem. Geol. 202 , 397–416 (2003). Algeo, TJ, Hong, H & Wang, C The chemical index of alteration (CIA) and interpretation of ACNK diagrams. Chem. Geol. 671 , https://doi.org/10.1016/j.chemgeo.2024.122474 (2025). Guo, Y, Yang, S, Su, N, Li, C, Yin, P & Wang, Z Revisiting the effects of hydrodynamic sorting and sedimentary recycling on chemical weathering indices. Geochim. Cosmochim. Acta 227 , 48–63 (2018). Parker, A An index of weathering for silicate rocks. Geol. Mag. 107 , 501–504 (1970). McLennan, SM Weathering and global denudation. J. Geol. 101 , 295–303 (1993). Hong, H, Zhao, L, Fang, Q, Algeo, TJ, Wang, C, Yu, J, Gong, N, Yin, K & Ji, K Volcanic sources and diagenetic alteration of Permian-Triassic boundary K-bentonites in Guizhou Province, South China. Palaeogeogr. Palaeoclimatol. Palaeoecol. 519 , 141–153 (2019). van de Kamp, PC Potassium distribution and metasomatism in pelites and schists: how and when, relation to postdepositional events. J. Sediment. Res. 86 , 683–711 (2016). Fedo, CM, Nesbitt, HW, Young, GM Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleoweathering conditions and provenance. Geology 23 (10), 921–924 (1995) Wang, C Metallogenic characteristics and prospective prediction of Dahaoshan gold deposit in the north Jiangxi province. Doctoral thesis at China University of Geosciences-Wuhan (2017) (in Chinese with English abstract) Huang, J, Feng, L, Lu, D, Zhang, Q, Sun, T & Chu, X Multiple climate cooling prior to Sturtian glaciations: Evidence from chemical index of alteration of sediments in South China. Sci. Rep. 4 , 6868 (2014). Gu, Z, Jian, X, Liu, G, Shen, X, Fu, H, Zhai, X & Jiang, H Age, provenance and tectonic setting of the Tonian-Cryogenian clastic successions in the northwest Bikou terrane, NW Yangtze Block, Central China. Precambrian Res. 397 , https//doi.org/10.1016/j.precamres.2023.107197 (2023). Dehler, CM, Schmitz, M, Bullard, A, Porter, S, Timmons, M, Karlstrom, K & Cothren, H Precise U-Pb age models refine Neoproterozoic western Laurentian rift initiation, correlation, and Earth system changes. Precambrian Res. 396 , https//doi.org/10.1016/j.precamres.2023.107156 (2023). Trower, EJ, Gutoski, JR, Wala, VT, Mackey, TJ & Simpson, C Tonian Low-Latitude Marine Ecosystems Were Cold Before Snowball Earth. Geophysical Research Letters 50 (5). doi.org/10.1029/2022gl101903. (2023) Trower, EJ, Ingalls, M, Gutoski, JR, & Wala, VT New constraints on phosphate concentration and temperature in shallow late Tonian seawater. Geology doi.org/10.1130/g53532.1. (2025) Hu, Z, Zhang, W, Liu, Y, Gao, S, Li, M, Zong, K, Chen, H & Hu, S "Wave" signal-smoothing and mercury-removing device for laser ablation quadrupole and multiple collector ICPMS analysis: application to lead isotope analysis. Anal. Chem. 87 , 1152–1157 (2014). Zong, K, Klemd, R, Yuan, Y, He, Z, Guo, J, Shi, X, Liu, Y, Hu, Z & Zhang, Z The assembly of Rodinia: the correlation of early Neoproterozoic (ca. 900 Ma) high-grade metamorphism and continental arc formation in the southern Beishan Orogen, southern Central Asian Orogenic Belt (CAOB). Precambrian Res. 290 , 32–48 (2017). Liu, Y, Hu, Z, Gao, S, Gunther, D, Xu, J, Gao, C & Chen, H In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard. Chem. Geol. 257 , 34–43 (2008). Gao, J, Feng, Q, Zhang, X, Zhou, L, Jiao, Z & Qin, Y Zircon U-Pb geochronology of crystal tuff on Lingshan Island and its geological implications for magmatism, stratigraphic age and geological events. Sci. Rep. 8 , https://doi.org/10.1038/s41598-018-30060-1 (2018). Lachance, GR & Claisse, F Quantitative X-ray Fluorescence Analysis Theory and Application. John Wiley & Sons (1995). Additional Declarations There is NO Competing Interest. 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1","display":"","copyAsset":false,"role":"figure","size":318626,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLocations of study sections. (A) \u003c/strong\u003eLate Tonian (~780 Ma) global paleogeography\u003csup\u003e12–14\u003c/sup\u003e. Craton abbreviations: Am, Amazonia; Aus, Australian cratons including Antarctic Mawsonland; Ba, Baltica; Ca, Cathaysia; Co, Congo; Ind, India; Ka, Kalahari; Laur, Laurentia; NC, North China; RP, Rio Plata; SF, São Francisco; Sib, Siberia; Tar, Tarim; WA, West African; Yz, Yangtze. \u003cstrong\u003e(B) \u003c/strong\u003ePaleogeographic reconstruction for the Yangtze Block during the Late Tonian\u003csup\u003e6\u003c/sup\u003e showing the location of study area (red rectangle) and referred sections (whit spots); \u003cstrong\u003e(C) \u003c/strong\u003eGeological map of the study area showing the location of outcrops.\u003c/p\u003e","description":"","filename":"image1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/b04ece31e75447c8eaa36833.jpeg"},{"id":93218529,"identity":"78160c66-8be0-437d-b16e-5dce7c486141","added_by":"auto","created_at":"2025-10-10 10:21:11","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":887012,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eLithological column and outcrop photographs in the Shimentang section. (A)\u003c/strong\u003e Boundary between Xiaomuping slate and Dayaogu conglomerate at –6 m; \u003cstrong\u003e(B) \u003c/strong\u003eLow-angle cross-stratification at 15 m; \u003cstrong\u003e(C)\u003c/strong\u003e Sandstone with rounded conglomerate at 70 m, representing the Liantuo Formation; \u003cstrong\u003e(D)\u003c/strong\u003e Tuff layer (red dashed line) and grayish-green and grayish purple siltstone at 112 m; \u003cstrong\u003e(E)\u003c/strong\u003e Thin to medium-bedded (~10 cm) coarse-grained quartz sandstone at 130 m; \u003cstrong\u003e(F)\u003c/strong\u003e Ripple cross-bedded siltstone-mudstone at 139 m (white dashed rectangle); \u003cstrong\u003e(G)\u003c/strong\u003e Unconformity between the Liantuo sandstone and Datangpo Mn-enriched shale at 183 m (white dashed line); the dated sandstone sample is from the uppermost Liantuo Formation below the unconformity; note notebook for scale (190 × 130 mm); \u003cstrong\u003e(H) \u003c/strong\u003eDiamictite at 200 m representing the Nantuo Formation; \u003cstrong\u003e(I)\u003c/strong\u003e Gray to dark gray medium-thick dolostone representing the cap dolostone of the lowermost Doushantuo Formation. Heights above 0 m are from Outcrop 1, whereas those below 0 m correspond to Outcrop 2. Abbreviations: XMP = Xiaomuping Formation; DTP = Datangpo Formation; NT = Nantuo Formation. Ed. = Ediacaran; DST = Doushantuo Formation; Per. = Period; Fm. = Formation; Litho. = Lithology.\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/0eddd50f43b1fb350b5e914f.jpeg"},{"id":93219492,"identity":"f1e8ad8f-46f9-4378-b9a1-8634623c6cae","added_by":"auto","created_at":"2025-10-10 10:29:11","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":535291,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThin-section photomicrographs of tuff at 112 m. (A) \u003c/strong\u003eNeedle-shaped vitric fragments; \u003cstrong\u003e(B) \u003c/strong\u003eVesicular structures generated from volcanic gases; \u003cstrong\u003e(C-D)\u003c/strong\u003e Crystal fragments composed of angular quartz (white arrows) and plagioclase (yellow arrows). Panels A to C are in plane-polarized light, while panels D is in cross-polarized light.\u003c/p\u003e","description":"","filename":"image3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/7f23f91a5fe0b6ecaa218947.jpeg"},{"id":93218532,"identity":"95059d74-21a4-4b0f-b72b-c5b3b9226792","added_by":"auto","created_at":"2025-10-10 10:21:11","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":570851,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eZircon LA-ICP-MS U-Pb ages. (A, C) \u003c/strong\u003eU-Pb concordia diagrams for the tuff and sandstone samples. \u003cstrong\u003e(B, D) \u003c/strong\u003eWeighted mean \u003csup\u003e206\u003c/sup\u003ePb/\u003csup\u003e238\u003c/sup\u003eU ages. Each bar represents the date and uncertainty (1σ) of individual zircon grains. MSWD: mean square weighted deviation. Uncertainty of mean ages was calculated at the 95% confidence interval. \u003cstrong\u003e(E, F)\u003c/strong\u003e Cathodoluminescence images of representative zircons. Yellow circles show the location of U-Pb analysis spots (32 μm width).\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/57ce45c1afd33d109f169506.jpeg"},{"id":93218530,"identity":"9b342f9e-4aa5-4314-be04-c181c0a8598c","added_by":"auto","created_at":"2025-10-10 10:21:11","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":215298,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eGeochemical profile for the Shimentang section.\u003c/strong\u003e (A) A-CN-K (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-(CaO*+Na\u003csub\u003e2\u003c/sub\u003eO)-K\u003csub\u003e2\u003c/sub\u003eO) diagram. Three quasi-parallel weathering trends are evident: (1) Weathering Trend 1 (0-74 m), (2) Weathering Trend 2 (74-120 m), and (3) Weathering Trend 3 (120-200 m). The arrows generally indicate an increase in the height of the lithological column. YC = average composition of the Yangtze Craton\u003csup\u003e26\u003c/sup\u003e. (B) CIA vs. Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/SiO\u003csub\u003e2\u003c/sub\u003e; (C) WIP vs. CIA. First-cycle (solid arrow) and polycyclic weathering (dashed arrow) lines are modified from reference\u003csup\u003e27\u003c/sup\u003e; (D) Th/Sc vs Zr/Sr. Two outliers may have been influenced by preferential preservation of zircons during polycyclic weathering. Lithological legends and abbreviations as in Figure 2.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/997a99eb747753ba4f78a901.jpeg"},{"id":93219669,"identity":"9829b750-1d0e-4b54-b59b-d909b9f9e2e9","added_by":"auto","created_at":"2025-10-10 10:37:11","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":775704,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePhotographs for the clast-bearing silty claystone in the Dayaogu Formation. \u003c/strong\u003e(A-F) Outcrop 1, Shimentang section; (G-H) Outcrop 2, Shimentang section; (I-J) Outcrop 3, Sidouzhu section; (K-L) Outcrop 4, Sidouzhu section.\u003c/p\u003e","description":"","filename":"image6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/a84d9b81f0c5552c3a05c120.jpeg"},{"id":93219494,"identity":"2991a226-c0ef-40e2-9fc8-9692f7d22662","added_by":"auto","created_at":"2025-10-10 10:29:11","extension":"jpeg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":857132,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThin-section photomicrographs of clast-bearing silty claystone for the Shimentang section in plane-polarized light. \u003c/strong\u003eSample height: (A) 32 m; (B) 39 m; (C) 40 m; (D-F) 50 m (microstructure marks are in their lower parts). Abbreviations: \u003cem\u003ee-e\u003c/em\u003e = edge-to-edge crushing (black dashed rectangles); \u003cem\u003egst\u003c/em\u003e = grain stacks (blue dashed lines); \u003cem\u003ert\u003c/em\u003e = rotation structures (orange arrows); \u003cem\u003edom\u003c/em\u003e = domains (black lines).\u003c/p\u003e","description":"","filename":"image7.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/977c4a4da2f67048fdd1d871.jpeg"},{"id":93218536,"identity":"66c63de9-9ba3-491d-ad9d-4f21b4e98a5f","added_by":"auto","created_at":"2025-10-10 10:21:11","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":434676,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDepositional ages and stratigraphic correlation for the glacial deposits from the late Tonian to Cryogenian in South China.\u003c/strong\u003e (A) Shennongjia\u003csup\u003e28\u003c/sup\u003e; (B) Changyang, Yichang\u003csup\u003e3,32\u003c/sup\u003e; (C) Three Gorges, Yichang\u003csup\u003e13,19,33\u003c/sup\u003e; (D) Shimentang, Tongshan (this study); (E) Sidouzhu, Tongshan\u003csup\u003e20,32\u003c/sup\u003e; (F) Longbizui, Guzhang\u003csup\u003e19,36\u003c/sup\u003e; (G) Sibao, Luocheng\u003csup\u003e19,34,35\u003c/sup\u003e. Abbreviations and other Lithological legends as in Figure 2. See Figure 1B for their locations.\u003c/p\u003e","description":"","filename":"image8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/00bb372484f0e1646cbd28b4.jpeg"},{"id":95526295,"identity":"00d1af80-6ee2-4d64-81ee-d9c0339eb06e","added_by":"auto","created_at":"2025-11-10 10:06:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5619273,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/6054c2e6-3e94-442b-b967-affaaf4e0316.pdf"},{"id":93219493,"identity":"8a5f35fb-5485-4785-a18f-3301a4ba8260","added_by":"auto","created_at":"2025-10-10 10:29:11","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1695756,"visible":true,"origin":"","legend":"Supplementary Information","description":"","filename":"SI.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7658226/v1/baf7ea1e50eaac7375df7036.pdf"}],"financialInterests":"There is \u003cb\u003eNO\u003c/b\u003e Competing Interest.","formattedTitle":"Tonian glaciation in South China","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe Neoproterozoic Snowball Earth episodes represent some of the most extreme climatic events recorded in the geologic record, with two global glaciations\u0026nbsp;characterized by icesheet expansion into low-latitude areas for millions of years, i.e.,\u0026nbsp;the Sturtian at ~717\u0026ndash;661 Ma\u003csup\u003e1\u0026ndash;3\u003c/sup\u003e and the Marinoan at \u0026le;650\u0026ndash;635 Ma\u003csup\u003e4,5\u003c/sup\u003e. However, paleoclimatic conditions during the preceding Tonian Period (1000\u0026ndash;720 Ma) remain poorly known. Indeed, the general scarcity of glacially influenced sedimentary rocks potentially indicates a stable and predominantly ice-free climate in that period\u003csup\u003e6\u003c/sup\u003e. However, several pre-Sturtian glacial deposits have been tentatively identified, which, if verified, would document climatic cooling preceding the Cryogenian Snowball Earth\u003csup\u003e7\u0026ndash;9\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eProposed pre-Sturtian glacial deposits include (1) the Kaigas Formation of the Gariep Belt on the Kalahari Craton\u003csup\u003e10\u003c/sup\u003e, (2) the Grand Conglomerate from the Kundelungu Basin on the Congo Craton\u003csup\u003e7\u003c/sup\u003e, (3) the Bayisi Diamictite on the Tarim Craton\u003csup\u003e8\u003c/sup\u003e, and (4) glaciolacustrine deposits of the Konnarock Formation in the southern Appalachians of Laurentia\u003csup\u003e9\u003c/sup\u003e. However, the significance of these formations as evidence of pre-Sturtian glaciation has been challenged on the basis of either age reassignment or re-interpretation of evidence for a glacial origin. For example, the glacial deposits of the Kalahari Craton that were previously assigned to the Kaigas Formation are now considered to belong to the syn-Sturtian (~717\u0026ndash;661 Ma) Numees Formation, while pre-Numees strata were re-interpreted as part of a fan delta depositional system\u003csup\u003e11\u003c/sup\u003e. Similarly, the Grand Conglomerate of the Congo has been dated to \u0026lt;727 Ma and is thus coeval with Sturtian glaciation\u003csup\u003e1\u003c/sup\u003e. The poorly sorted conglomerates of the Bayisi Diamictite are thought to have formed within a volcanic rift\u003csup\u003e8\u003c/sup\u003e, and evidence for a glaciogenic origin is lacking. Finally, the Konnarock Formation in the southern Appalachians formed at low paleolatitudes and is regarded as a local high-altitude glaciolacustrine deposit\u003csup\u003e9\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCratons at high paleolatitudes are more likely to record stratigraphic evidence of glaciation than those at lower paleolatitudes. Given the high-latitude location of the South China Block in the late Tonian\u003csup\u003e12\u0026ndash;14\u003c/sup\u003e (Fig. 1A), the South China has considerable potential to record Tonian-aged glacial events, even if they were of lesser intensity than later Cryogenian Snowball Earth events.\u003c/p\u003e\n\u003cp\u003eHere, we report sedimentological, geochronologic, and geochemical data from sedimentary rocks of the Liantuo Formation and the Dayaogu Formation in Tongshan area, South China. The U-Pb geochronology generating a depositional age from zircon grains in a tuff interbed, and a maximum depositional age from detrital zircon grains in a sandstone bed that immediately underlies an erosive unconformity at the top of the Liantuo Formation. The main goals of this study were to (1) identify whether there were glacial till deposits in the pre-Sturtian of the Tongshan section, (2) reconstruct patterns of climatic changes during the late Tonian in South China and their relationship to the documented glacial deposits, and (3) examine additional evidence from other regions that supports Tonian glacial events of possible global significance.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eGeological Setting\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe evolution of the Yangtze Block can be divided into 4 stages: ~1000-830 Ma pre-rifting, ~820-800 Ma early rifting, ~790-730 Ma peak rifting, and ~700-630 Ma late rifting\u003csup\u003e15\u003c/sup\u003e. The early and peak rifting stages record the initiation of deposition on the Yangtze Craton\u003csup\u003e16\u003c/sup\u003e. Metamorphosed to lightly-metamorphosed siliciclastic strata with widespread magmatism include the Banxi, Danzhou, Xiuning, Zhitang and Chengjiang formations (or groups), which unconformably overlie the basement beginning at ~820 Ma\u003csup\u003e17,18\u003c/sup\u003e.\u0026nbsp;Under the combined influence of external subduction-accretion and internal rifting tectonic dynamics during the late Tonian, the western margin of the Yangtze Block experienced continuous subduction, while the northern margin was characterized by subduction-accretionary orogeny. Such tectonic settings had created mainly arc-related volcanic basins on the outer northern margins (Fig. 1B). In comparison, due to the tectonic activities gradually decreasing from north to south, the paleogeographic environment also changed regularly from fluvial-littoral facies in the north to shallow marine to bathyal facies in the south (Fig. 1B)\u003csup\u003e6\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; The four study outcrops are located at the northern part of Tongshan County, Xianning City, Hubei Province (Fig. 1C). Outcrop 1 (GPS coordinates: 29\u0026deg;40\u0026prime;51\u0026Prime;N, 114\u0026deg;29\u0026prime;25\u0026Prime;E) displays, from bottom to top, the Tonian-aged Dayaogu Formation and Liantuo Formation, the Cryogenian-aged Datangpo Formation and Nantuo Formation, and the Ediacaran-aged Doushantuo Formation. Outcrop 2 (GPS coordinates: 29\u0026deg;40\u0026prime;32\u0026Prime;N, 114\u0026deg;29\u0026prime;11\u0026Prime;E), located approximately 500 meters southwest of Outcrop 1, exposes the Tonian-aged Xiaomuping Formation and the lower part of the Dayaogu Formation. By integrating the stratigraphic information from these two nearby outcrops, we constructed a complete stratigraphic sequence ranging from the uppermost Xiaomuping Formation to the lowermost Doushantuo Formation. This composite section is named as the Shimentang section, due to its proximity to the Shimentang reservoir.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOutcrops 3 (GPS coordinates: 29\u0026deg;39\u0026prime;38\u0026Prime;N, 114\u0026deg;27\u0026prime;34\u0026Prime;E) and 4 (GPS coordinates: 29\u0026deg;39\u0026prime;45\u0026Prime;N, 114\u0026deg;27\u0026prime;60\u0026Prime;E) are situated ~3 km southwest of the Shimentang section and are seriously covered by Quaternary deposits. They expose the same stratigraphic sequence ranging from the Tonian-aged Xiaomuping Formation to the Cryogenian-aged Nantuo Formation. Each stratigraphic unit is notably thicker compared to those in the Shimentang section, and the sequence includes the Sturtian-aged Gucheng Formation, which is not present at Shimentang. Because these two outcrops are located on opposite sides of the Sidouzhu Reservoir, they are collectively referred to as the Sidouzhu Section.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eLithological description\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBased on lithological characteristics, detailed measurements of the Shimentang section (Outcrops 1 and 2) have led to the identification of ten distinct stratigraphic units (Fig. 2). It should be noted that the descriptions for heights below 0 m are from Outcrop 2, whereas those above 0 m correspond to Outcrop 1.\u003c/p\u003e\n\u003cp\u003eUnit 1 (\u0026ndash;15.5 to \u0026ndash;6 m): The underlying unit consists of gray to grayish-green slate. This unit is regarded as the Xiaomuping Formation. This slate is overlain by conglomerate of the base of the Dayaogu Formation (Fig. 2A).\u003c/p\u003e\n\u003cp\u003eUnit 2 (\u0026ndash;6 to 30 m): This unit is primarily composed of grayish-green to grayish-yellow silty mudstone, characterized by low-angle cross-stratification (Fig. 2B).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnit 3 (30 to 51 m): This unit is grayish-yellow to grayish-green, poorly sorted, clast-bearing silty claystone lacking bedding. It is interpreted as glacial till and will be described in detail in Discussion section.\u003c/p\u003e\n\u003cp\u003eUnit 4 (51 to 66 m): This unit is dominated by grayish-green siltstone to grayish-yellow silty mudstone.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnit 5 (66 to 74 m): This unit is a grayish-green, rounded clast-bearing silty claystone that lacks distinct bedding. The clasts range in size from 0.2 to 2 cm and are poorly sorted (Fig. 2C). It unconformably overlies Unit 4. Units 2 to 4 are assigned to the Dayaogou Formation, whereas Unit 5 is considered the base of the Liantuo Formation.\u003c/p\u003e\n\u003cp\u003eUnit 6 (74 to 125 m): This unit is dominated by grayish-green siltstone-sandstone interbedded with grayish-purple siltstone (Fig. 2D). The thickness of the differently colored siltstone layers ranges from less than 1 cm to ~10 cm. Horizontally laminated bedding is occasionally observed within these siltstones. In the middle of this unit is a grayish to off-white tuff layer at 112 m, which is easily distinguishable from the surrounding grayish-green siltstone/sandstone (Fig. 2D red dashed lines). The tuff layer is mainly composed of vitric fragments, crystal fragments, lithic fragments and clay matrix. Devitrification of vitric fragments during diagenesis has produced needle-like structures (Fig. 3A). Vesicular structures filled with felsic minerals are also present (Fig. 3B). In addition, crystal fragments are mainly composed of angular quartz (Fig. 3C and D, white arrows) and plagioclase (Fig. 3C and D, yellow arrows). Petrological evidence demonstrates a volcanic origin for this tuff.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnit 7 (125 to 183 m): The lowermost (125 to 135 m) and uppermost (174 to 183 m) of this units is a medium-bedded (~10 cm) gray coarse-grained quartz sandstone (Fig. 2E). The middle of this unit is dominated by dark-gray clay-rich mudstone interbedded with grayish-yellow siltstone showing graded bedding. Ripple cross-bedded siltstone is observed at 172 m, which may have been formed above the wave base (Fig. 2F, white dashed rectangle).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eUnit 8 (183 to 195 m): A Mn-enriched black shale unconformably overlies the sandstone (Fig. 2G), which is consistent with the characteristics of the Mn-enriched shale of the Datangpo Formation. Thus, the Sturtian-aged Gucheng diamictite is not present in the Northern Tongshan section. This observation is consistent with outcrops in the Three Gorges area, where both the Gucheng and Datangpo formations are missing\u003csup\u003e19\u003c/sup\u003e. Their local absence may be due to insufficient accommodation space resulting from sea-level fall.\u003c/p\u003e\n\u003cp\u003eUnit 9 (195 to 230 m): Diamictite with subrounded to subangular clasts (0.5-15 cm diam.) of quartz, feldspar, granite, diorite and sandstone, representing the Marinoan-aged Nantuo Formation (Fig. 2H).\u003c/p\u003e\n\u003cp\u003eUnit 10 (\u0026gt;230 m): Gray to dark gray medium-thick dolostone representing the cap dolostone of the lowermost Doushantuo Formation. The outcrop is severely covered in this unit (Fig. 2I).\u003c/p\u003e\n\u003cp\u003eThe stratigraphic sequence of the Sidouzhu section (outcrops 3 and 4) is broadly comparable to that of the Shimentang section, encompassing strata from the Tonian-aged Xiaomuping Formation to the Cryogenian-aged Nantuo Formation. Each formation in the Sidouzhu section is significantly thicker and may have undergone slight metamorphism\u003csup\u003e20\u003c/sup\u003e. Additionally, the sequence contains the Sturtian-aged Gucheng Formation, which is absent in the Shimentang section. Due to extensive Quaternary deposits obscuring the area, detailed stratigraphic units are not described. Instead, the lithological column is constructed based on a synthesis of two prior investigations conducted in this section\u003csup\u003e20,21\u003c/sup\u003e. Photographs documenting potential glacial till deposits were collected at all four outcrops (see Discussion).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eZircon LA-ICP-MS U-Pb ages\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe results of LA-ICP-MS U-Pb dating of zircons in the tuff (112 m, \u003cem\u003en\u003c/em\u003e = 120) and sandstone (182 m, \u003cem\u003en\u003c/em\u003e = 120) samples are presented in Supplementary Tables 1 and 2. In the tuff sample, the zircon grains are 90\u0026ndash;150 \u0026mu;m long and 35\u0026ndash;50 \u0026mu;m wide (Fig. 4A, inset photograph), and in the sandstone sample they are relatively irregular and spherical-elliptical with diameters in the range of 20\u0026ndash;150 \u0026mu;m (Fig. 4C, rounded inset), consistent with abrasion during transport. All zircon grains are transparent to pale yellow in color and display a euhedral to subhedral shape, with clear oscillatory growth zones under cathodoluminescence (Fig. 4E-F). In addition, nearly all grains (233 of 240) yield Th/U \u0026gt; 0.4, consistent with magmatic origins\u003csup\u003e22\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eZircon grains from the tuff sample have Th concentrations ranging from 40\u0026ndash;1090 ppm and U contents ranging from 45\u0026ndash;442 ppm. Of 120 grains, 91 exhibit a concordance of \u0026gt;90%. The zircon U-Pb ages range from 618\u0026ndash;854 Ma and can be divided into three groups (Fig. 4A). The Group 1 contains 7 grains with a dispersed age distribution (618\u0026ndash;694 Ma) that generally deviates from the line of concordance. The relatively concentrated ages within this group yield a weighted mean \u003csup\u003e206\u003c/sup\u003ePb/\u003csup\u003e238\u003c/sup\u003eU age of 674.0 \u0026plusmn; 5.2 Ma, which is associated with an anomalously high MSWD value of 27 (\u003cem\u003en\u0026nbsp;\u003c/em\u003e= 6), suggesting dispersion possibly due to Pb loss. Additionally, the age of 674.0 \u0026plusmn; 5.2 Ma corresponds to the Marinoan Glaciation, represented by the overlying Nantuo Formation, and is significantly younger than the known depositional age of the Liantuo Formation (ca. 780\u0026ndash;714 Ma\u003csup\u003e13,19,23\u003c/sup\u003e). Therefore, zircon grains from Group 1 cannot be interpreted as representing the depositional age of this tuff layer. The Group 2 comprises 74 grains that yield a weighted mean \u003csup\u003e206\u003c/sup\u003ePb/\u003csup\u003e238\u003c/sup\u003eU age of 747.2 \u0026plusmn; 1.9 Ma (MSWD = 0.87, \u003cem\u003en\u003c/em\u003e = 74) (Fig. 4B). The third group contains 10 grains with ages of 769\u0026ndash;854 Ma, which can be linked to magmatic episodes in South China at 780\u0026ndash;745 Ma and 820\u0026ndash;800 Ma\u003csup\u003e16\u003c/sup\u003e. Since the ages of the zircons of Groups 1 and 3 can be attributed to Pb loss and older magmatic activity, respectively, the U-Pb age cluster of Group 2 (747.2 \u0026plusmn; 1.9 Ma) represents the best estimate of the age of tuff eruption and deposition.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn the sandstone sample, 111 of 120 zircon grains exhibit a concordance of \u0026gt;90% (Fig. 4C). The youngest detrital zircon grains in a siliciclastic rock sample are commonly used to interpret its maximum depositional age\u003csup\u003e24\u003c/sup\u003e. In this sample, the youngest group of U-Pb ages, consisting of 89 zircon grains, ranges from 987 to 715 Ma (Fig. 4C, rectangular inset), and the youngest cluster of ages yields a maximum depositional age of 722.9 \u0026plusmn; 4.5 Ma (MSWD = 0.77,\u003cem\u003e\u0026nbsp;n\u0026nbsp;\u003c/em\u003e= 12) (Fig. 4D). Thus, the age of the uppermost Liantuo Formation in the Northern Tongshan section is interpreted to be younger than 722.9 \u0026plusmn; 4.5 Ma, which is close to the onset of the Sturtian Snowball glaciation at ca. 717 Ma\u003csup\u003e2,25\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eWeathering proxies\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eChemical Index of Alteration (CIA) values are listed in Supplementary Table 3. The study interval exhibits three major declines in weathering proxies, in the lower (15.15 m), middle (114.00 m) and uppermost (198.95 m) parts of the section (Fig. 5). CIA values decrease from 71 to 67 at 15.15 m and increase to 78 at 53.25 m. Above this level, CIA values gradually decrease to 62 at 114.0 m and then increase to 74 at 155.3 m. In the uppermost interval (to 198.95 m), CIA values decrease once more, from 74 to 67.\u0026nbsp;\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003e\u003cstrong\u003eCharacterization of glacial deposition\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe grayish-yellow to grayish-green, poorly sorted, clast-bearing silty claystone observed in all four outcrops of the Dayaogu Formation is interpreted as glacial till (Fig. 6). The clasts range in diameter from 0.2 mm to ~30 cm (Fig. 6A and I yellow arrow), and consist of quartz, feldspar, granite, and diorite (Fig. 6C and L). Clast shapes include subrounded prolate shape (Fig. 6B), rounded shape (Fig. 6C), oblate shape (Fig. 6F), and subrounded/subangular shape with poor sorting (Fig. 6D, K, and L). In particular, scratches that may have been formed from glacier movement can be found in oblate-shape clasts (Fig. 6F yellow arrows).\u003c/p\u003e\n\u003cp\u003eThese characteristics collectively provide a robust set of criteria for identifying the deposit as a glacial till, effectively distinguishing it from other diamictites of similar appearance but different origin, such as those formed in fluvial and debris flow. Fluvial conglomerates are characterized by moderate to good sorting and a high degree of clast roundness due to prolonged abrasion during bedload transport (e.g., Fig. 2C). They typically exhibit clast imbrication, where elongated pebbles are oriented with their flat planes dipping upstream, and are supported by a well-sorted sandy matrix\u003csup\u003e28\u003c/sup\u003e. In contrast, the Dayaogu deposit shows extremely poor sorting with a wide, unstructured grain-size distribution and a clay-silt matrix, which is inconsistent with the winnowing and sorting action of consistent hydraulic flow. The presence of both well-rounded and subangular clasts is a key indicator (e.g., Fig. 6I-L); the rounded clasts are likely reworked from pre-existing deposits and incorporated into the ice without significant further abrasion, a common feature in tills. While debris flow deposits (lahars, mudflows) can also be poorly sorted and matrix-supported. The most definitive differentiating feature is the presence of glacial striations (scratches) observed on the oblate clasts. These parallel, linear grooves are formed by subglacial abrasion as debris-laden ice grinds over a substrate. This is a hallmark of glacial transport virtually never replicated in the high-fluid-content, short-duration shear environment of a debris flow. In addition, debris flow deposits are typically of limited lateral extent; in contrast, this particular diamictite unit may has been observed in numerous sections across the Yangtze Block (see Discussion of Figure 8).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe forcible embedding of clasts is evident in photomicrographs. Edge-to-edge crushing (\u003cem\u003ee-e\u003c/em\u003e) microstructures are found in samples at 32 m (Fig. 7A, black dashed rectangles). The \u003cem\u003ee-e\u003c/em\u003e microstructures developed at the earliest stages of subglacial till formation as soon as the sediment experienced strain\u003csup\u003e29\u003c/sup\u003e and can be easily destroyed by development of other structures. Thus, the existence of \u003cem\u003ee-e\u003c/em\u003e microstructures for this sample may indicate limited reworking by subsequent glacial outwash or flowing water. Grain stacks (\u003cem\u003egst\u003c/em\u003e) are observed in most samples of this unit as linear arrangements of grains that form as two sets of conjugate structures, likely indicative of simple shear deformation (Fig. 7D-F, blue dashed lines). Grain stacks evolved after \u003cem\u003ee-e\u003c/em\u003e and are an important kinematic marker of till deformation\u003csup\u003e29\u003c/sup\u003e. Rotation structures (\u003cem\u003ert\u003c/em\u003e) are also common in this unit (Fig. 7, orange arrows). This microstructure is often observed in fine-grained subglacial tills with relatively high clay content (\u0026gt;20%\u003csup\u003e30\u003c/sup\u003e), reflecting plastic flow during subglacial deformation. Because \u003cem\u003egst\u003c/em\u003e are commonly twisted around \u003cem\u003ert\u003c/em\u003e of larger clasts (Fig. 7D and E), the \u003cem\u003ert\u003c/em\u003e is interpreted to have formed later than \u003cem\u003egst\u003c/em\u003e. Another feature typical of subglacial tills is the presence of multiple domains (\u003cem\u003edom\u003c/em\u003e) of often slightly different or in some cases very different lithofacies units that have all been incorporated into the subglacial till (Fig. 7F, black lines)\u003csup\u003e31\u003c/sup\u003e. The domains are found at 50 m and are likely formed due to previously deposited sediments being incorporated into the subglacial till and subsequently moving within a mobile soft-sediment subglacial bed prior to final emplacement\u003csup\u003e31\u003c/sup\u003e. All macroscopic and microscopic characteristics of the clasts are consistent with glacial till deposition.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDepositional ages and stratigraphic correlation of Tonian Glacial deposits\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe 747.2 \u0026plusmn; 1.9 Ma age of the tuff at 112 m indicates that the glacial deposits in the Dayonggu Formation of the Shimentang section are almost certainly of late Tonian age. Tuffs dated to approximately 750 Ma have also been identified in the middle of the overlying Liantuo Formation from several nearby outcrops in Hubei Province, suggesting that the same tuff layer may be present regionally (Fig. 8A-D; pink dashed line). In the Shennongjia area, a fine-bedded tuff yielded a youngest population of zircon grains (20 of 35) with a concordant age of 752 \u0026plusmn; 6.5 Ma\u003csup\u003e28\u003c/sup\u003e (Fig. 8A). In the Changyang section, a tuff yielded a youngest group of zircon grains (21 of 35) with a concordant age of 751.5 \u0026plusmn; 6.3 Ma\u003csup\u003e32\u003c/sup\u003e (Fig. 8B). In the Three Gorges area, tuffs from the middle to upper parts of the Liantuo Formation yielded a youngest zircon age cluster of 748 \u0026plusmn; 12 Ma\u003csup\u003e33\u003c/sup\u003e (Fig. 8C). These chronological studies confirm that the Liantuo Formation was deposited during the late Tonian Period.\u003c/p\u003e\n\u003cp\u003eThe youngest cluster of ages from detrital zircons in the uppermost beds of the Liantuo Formation (722.9 \u0026plusmn; 4.5 Ma) is similar to those of tuffs from the top of the Liantuo Formation (Fig. 8A and C), suggesting the maximum depositional age of this sandstone is close to its true depositional age. The absence of the Sturtian-aged Gucheng Formation may be attributed to insufficient accommodation space resulting from a glacio-eustatic sea-level fall during the early Cryogenian. Similar stratigraphic relationships have also been observed in other sections, where the Liantuo Formation is unconformably overlain by the Marinoan-aged Nantuo Formation (e.g., Fig. 8C). Given a magmatic zircon age of 660.1 \u0026plusmn; 3.6 Ma for the basal Datangpo Formation (Fig. 8B), this unconformity represents a ~60-Myr-long hiatus in the Shimentang section.\u003c/p\u003e\n\u003cp\u003eIn the nearby Sidouzhu section, the depositional age of these glacial deposits has been further constrained to between 823 Ma and 760.5 Ma (Fig. 8E) based on a detrital zircon age of 816 \u0026plusmn; 7 Ma from the base of the Dayaogu Formation\u003csup\u003e20\u003c/sup\u003e and a magmatic zircon age of 764.1 \u0026plusmn; 3.6 Ma from the base of the Liantuo Formation\u003csup\u003e32\u003c/sup\u003e. This suggests a potential correlation between these glacial deposits and the controversial Chang\u0026rsquo;an Formation, which was proposed to be associated with the so-called \u0026ldquo;Kaigas Glaciation\u0026rdquo;\u003csup\u003e34,35\u003c/sup\u003e. Although the concept of the \u0026ldquo;Kaigas Glaciation\u0026rdquo; has recently been challenged by Pu et al.\u003csup\u003e11\u003c/sup\u003e, zircon ages obtained from the base of this diamictite unit support the existence of pre-Sturtian glacial deposits in South China (Fig. 8F\u0026ndash;G) and provide tighter age constraints for this glacial till sequence at 792.1\u0026ndash;773 Ma. In addition, these deposits exhibit a wide spatial distribution, extending from nearshore to shallow marine environments (Fig. 1B).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePaleoclimate in the Shimentang section and global evidence for Pre-Sturtian Glaciations\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe chemical index of alteration has been applied as a proxy for paleoclimatic change in many studies\u003csup\u003e37\u0026ndash;39\u003c/sup\u003e. However, it is imperative to assess influences related to sedimentary provenance, grain size, sediment recycling, and K-metasomatism in order to avoid potential misinterpretations of CIA signals\u003csup\u003e27,40,41\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eChanges in protolith composition can influence the chemical composition of the weathering product\u003csup\u003e40\u003c/sup\u003e, so it is first necessary to evaluate the protolith in order to draw paleoclimate inferences based on variations in weathering proxy data. Ternary A-CN-K (i.e., molar Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e-(Na\u003csub\u003e2\u003c/sub\u003eO+CaO*)-K\u003csub\u003e2\u003c/sub\u003eO) diagrams can permit inferences about protolith composition\u003csup\u003e41\u003c/sup\u003e. In the present study section, three parallel weathering trends are observed, with one trend (Trend 1, pink dashed arrow; Fig. 5A) showing relatively greater weathering intensity than the other two trends (Trends 2 and 3, yellow and blue dashed arrows; Fig. 5A). The weathering trends 2 and 3 can be extended backward to a point that represents the average composition of the Yangtze Craton\u003csup\u003e26\u003c/sup\u003e, suggesting derivation from a mixture of regionally weathered material, whereas Trend 1 shows a markedly more mafic protolith, suggesting more localized weathering sources. Although the exact cause of this shift cannot be determined, several possible influences can be identified: (1) changes in sea level or glacial cycles resulting in submergence or exposure of terrigenous source areas; (2) changes in river drainage systems (e.g., the presence of fluvial deposits at the Liantuo Formation may indicate development of a new estuary); and/or (3) major tectonic movements during rifting of the Yangtze Craton, exposing new rock units to weathering.\u003c/p\u003e\n\u003cp\u003eHydrodynamic sorting segregates detrital minerals according to their size, shape and density, leading to geochemical differentiation in sediments\u003csup\u003e41\u003c/sup\u003e. Therefore, weathering indices based on sediment chemistry may reflect not only weathering intensity also hydraulic changes during sediment transport and deposition. Grain size, as a result of hydrodynamic sorting, can be represented by molar Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/SiO\u003csub\u003e2\u003c/sub\u003e ratios\u003csup\u003e42\u003c/sup\u003e. However, only a weak correlation is apparent between Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e/SiO\u003csub\u003e2\u003c/sub\u003e and CIA (\u003cem\u003er\u003c/em\u003e = +0.14, \u003cem\u003en\u003c/em\u003e = 28, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001), suggesting a limited influence from hydrodynamic sorting (Fig. 5B). It is possible that the samples of Trend 1 (0-80 m) were derived from the same protolith as those of Trends 2 and 3 (\u0026gt; 80 m), but that lower energy conditions of deposition of the former resulted in the preferential accumulation of fines, shifting Trend 1 toward higher Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e compositions relative to the other trends. Given the tentativeness of this inference, no correction procedure was applied.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA WIP (Weathering Index\u003csup\u003e43\u003c/sup\u003e) vs. CIA diagram can be used to evaluate whether samples have undergone significant sedimentary recycling. The relationship between CIA and WIP is linear for first-cycle muds and sands\u003csup\u003e27\u003c/sup\u003e. However, recycled samples display quartz dilution produced by physical processes in chemical-weathering-limited conditions. The effect of quartz dilution is most easily detected in more arid regions, where recycling is indicated by low WIP despite low CIA (Fig. 5C, dashed line). The proximity of all present study samples to the first-cycle weathering line suggests a minimal influence from sedimentary recycling (Fig. 5C). Furthermore, the relatively strong covariation of Zr/Sc and Th/Sc in most samples (30 of 32) also indicates that these samples likely originated from first-cycle weathering (\u003cem\u003er\u003c/em\u003e = +0.83, \u003cem\u003en\u003c/em\u003e = 31, \u003cem\u003ep\u003c/em\u003e \u0026lt; 0.001, Fig. 5D). This is because first-cycle sedimentary deposits exhibit strong positive covariation of Zr/Sc and Th/Sc and a compositional variation trend reflective of the source rock. Recycled sediments, in contrast, exhibit greater variation in Zr/Sc than Th/Sc owing to preferential preservation of zircons\u003csup\u003e44\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eK-metasomatism results from the alteration of rocks by hydrothermal or magmatic fluids, a process that typically introduces excess K\u003csub\u003e2\u003c/sub\u003eO and leads to formation of secondary K-bearing minerals\u003csup\u003e45\u003c/sup\u003e or replacement of plagioclase by K-feldspar\u003csup\u003e46\u003c/sup\u003e. Metasomatic introduction of K\u003csub\u003e2\u003c/sub\u003eO lowers measured CIA values, making quantitative corrections for K-metasomatic effects necessary to recover primary weathering signals.\u0026nbsp;The most widely used method is based on the concept of an \u0026ldquo;ideal weathering trend\u0026rdquo; that aligns parallel to the A-CN axis\u003csup\u003e47\u003c/sup\u003e. However, given the observed substantial variability of actual weathering trends in modern soil profiles, Algeo et al.\u003csup\u003e41\u003c/sup\u003e demonstrated that reliance on an \u0026ldquo;ideal weathering trend\u0026rdquo; may result in unwarranted inferences regarding K-metasomatism and inaccurate correction of CIA values. They further argued that highly aligned data arrays in A-CN-K space generally represent original weathering trends. In this study, although a low-temperature hydrothermal deposit is present in northern Jiangxi Province (~300 km east of Tongshan\u003csup\u003e48\u003c/sup\u003e), we infer that the present study samples were unaffected (or minimally affected) by K-metasomatism for the following reasons: (1) the A-CN-K relations of the study samples reveal three separate weathering trends, each developed within a discrete stratigraphic interval of the study section, that are aligned and quasi-parallel to each other, extending from the feldspar line to the illite pole; (2) none of these weathering trends shows a significant deviation towards the K apex; and (3) Eu/Eu* values range from 0.74 to 1.41 (Supplementary Table 4, mean 1.07 \u0026plusmn; 0.16). Therefore, no correction procedure was applied for K-metasomatic effects.\u003c/p\u003e\n\u003cp\u003eThe CIA profile suggests that two intervals were deposited under relatively cooler and/or more arid climatic conditions (Fig. 5A). The older glacial event interval (GE-I) shows distinct characteristics that support glacial deposition and constrained to 792.1\u0026ndash;773 Ma according to stratigraphic correlation. Given the high paleolatitude of the South China Block at ~780 Ma (cf. Fig. 1A), these ice-contact deposits likely reflect the existence of glaciers and/or icesheets in the Northern Hemisphere polar region at that time. The younger glacial event interval (GE-II), however, shows no clear sedimentological evidence for ice-contact deposition. Here, the age of 747.2 \u0026plusmn; 1.9 Ma from a tuff interbed supports broad temporal equivalence with cool climatic conditions recorded in the ca. 750 Ma Konnarock Formation of the southern Appalachians, Laurentia\u003csup\u003e9\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThese GEs can also be evident from CIA across disparate paleocontinental settings, with decreased CIA not only in South China\u003csup\u003e28,49,50\u003c/sup\u003e but also in the Grand Canyon in North America\u003csup\u003e51\u003c/sup\u003e. In addition, the recent observation of petrographic fingerprints of ikaite from North America\u0026mdash;a mineral that typically forms in near-freezing sedimentary environments\u0026mdash;in late Tonian strata (780\u0026ndash;730 Ma) was interpreted as evidence that low-latitude shallow marine environments were cold prior to the Cryogenian Period\u003csup\u003e52,53\u003c/sup\u003e. Together, these transcontinental records provide relatively robust evidence for pre-Sturtian glaciations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWe investigated U-Pb geochronology and paleoweathering for a Tonian outcrop section at Tongshan, South China. Based on sedimentological and geochemical evidence, we propose the existence of two relatively colder climatic intervals: GE-I at ~780 Ma and GE-II at ~750 Ma. The earlier colder interval was accompanied by the deposition of glacial till on the South China Block. We suggest that the higher paleolatitude of the South China Block enabled the proximal development of glaciers (and possibly icesheets) at GE-I. Conversely, no sedimentological evidence for glacial deposition has been recorded for the GE-II in South China, but this interval coincides with low latitude (high altitude) glaciolacustrine strata in Laurentia. Our study thus reveals multiple intervals of global cooling during the Tonian, thereby adding important new constraints for the accurate calibration of global Earth System models that aim to reconstruct climatic conditions in advance of the Sturtian Snowball Earth.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003e\u003cstrong\u003eZircon U-Pb geochronology\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the Shimentang section, a tuff in the middle of the Liantuo Formation (at 112 m) and a sandstone bed near its top (at 182 m) were sampled for zircon U-Pb dating. Approximately 3.3 kg of volcanic tuff and 2.5 kg of sandstone were powdered to 60 mesh and processed to recover zircon concentrates using conventional magnetic and density separation techniques in a clean lab at the State Key Laboratory of Geomicrobiology and Environmental Geology, China University of Geosciences-Wuhan. Zircon grains were handpicked from each sample under a stereoscopic microscope, mounted onto 2.54-cm epoxy disks, and polished to expose an interior cross-section of each grain.\u003c/p\u003e\n\u003cp\u003eAll zircon grains were documented with cathodoluminescence images to observe their internal structure and to identify any detrital or inherited components. An Analytical Scanning Electron Microscope (JSM-IT100) connected to a GATAN MINICL system was used to generate cathodoluminescence images. The imaging conditions included a 10.0\u0026ndash;13.0 kV electric field and an 80\u0026ndash;85 \u0026mu;A current through a tungsten filament.\u003c/p\u003e\n\u003cp\u003eMeasurements of U, Th, Pb and other trace elements were performed by LA-ICP-MS at Wuhan Sample Solution Analytical Technology Co. Laser sampling was conducted using a GeolasPro laser ablation system that consists of a COMPexPro 102 ArF excimer laser and a MicroLas optical system. An Agilent 7700e ICP-MS instrument was used to acquire ion-signal intensities. The laser was operated at a wavelength of 193 nm and maximum energy of 200 mJ. The laser spot size and frequency were set to 32 \u0026mu;m and 5 Hz, respectively. Helium was used as a carrier gas and argon was used as the make-up gas, which was mixed with the carrier gas via a T-connector before entering the ICP. A \u0026ldquo;wire\u0026rdquo; signal smoothing device was included in the laser ablation system\u003csup\u003e54\u003c/sup\u003e. Each analysis included a background acquisition of approximately 20 s (gas blank), followed by 50 s of data acquisition from the sample. Detailed operating conditions for the laser ablation system and the ICP-MS instrument, as well as the data reduction method, followed those of Zong et al.\u003csup\u003e55\u003c/sup\u003e. An Excel-based software, ICPMSDataCal 10.9, was used to perform off-line selection and integration of background and analyzed signals, time-drift correction and quantitative calibration for trace element analysis and U-Pb dating\u003csup\u003e56\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo ensure the reliability of the data, zircon 91500, GJ-1, Ple, Tanz, and SRM 610 were used as external standards for U-Pb dating and trace element calibration, and the zircon GJ-1 was used as a second standard to monitor data quality. The 91500 standard was analyzed twice for every 7 unknowns. Concordia diagrams for U-Pb isotopic ratios and weighted mean calculations were made using Isoplot 3.0. Because old zircons can contain large amounts of radiogenic Pb, \u003csup\u003e207\u003c/sup\u003ePb/\u003csup\u003e206\u003c/sup\u003ePb ages were adopted for zircons with ages \u0026gt;1000 Ma, and \u003csup\u003e206\u003c/sup\u003ePb/\u003csup\u003e238\u003c/sup\u003eU ages were adopted for zircons with ages \u0026lt;1000 Ma\u003csup\u003e57\u003c/sup\u003e. The age data and Th/U ratios are listed in Supplementary Tables 1 and 2.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMajor element analysis and weathering proxies\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMajor element concentration data for 28 bulk samples (avoiding large clasts in till samples) were analyzed on a Zsx Primus II wavelength dispersive X-ray fluorescence spectrometer at the Wuhan Sample Solution Analytical Technology Co. These data were calibrated using national standard materials GBW07101-14, GBW07401-08 and GBW07302-12, and corrected by the theoretical \u0026alpha; coefficient method\u003csup\u003e58\u003c/sup\u003e, yielding relative standard deviations of less than 2% for all elements of interest.\u003c/p\u003e\n\u003cp\u003eThe chemical index of alteration (CIA) was applied to evaluate variation in paleoweathering intensity\u003csup\u003e37,41\u003c/sup\u003e: CIA = molar [(Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e) / (Al\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e3\u003c/sub\u003e + CaO* + Na\u003csub\u003e2\u003c/sub\u003eO + K\u003csub\u003e2\u003c/sub\u003eO)] \u0026times; 100, where CaO* represents CaO in silicate minerals. Here, CaO* was corrected for Ca associated with phosphate (CaO* = molar CaO \u0026ndash; molar P\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e \u0026times; 10/3). If the calculated CaO* content was greater than Na\u003csub\u003e2\u003c/sub\u003eO, then Na\u003csub\u003e2\u003c/sub\u003eO was used in place of CaO*\u003csup\u003e44\u003c/sup\u003e. This correction is applicable exclusively to materials with relatively felsic protoliths, i.e., \u0026gt;60 wt% SiO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e41\u003c/sup\u003e, a condition met by all of the present study samples (Supplementary Table 3). In addition, in order to evaluate any potential influence and multi-cyclic weathering, we calculated the Weathering Index (WIP\u003csup\u003e43\u003c/sup\u003e), expressed as: WIP = molar (CaO*/0.7 + 2Na\u003csub\u003e2\u003c/sub\u003eO/0.35 + 2K\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003ecorr\u003c/sub\u003e/0.25 + MgO/0.9) \u0026times; 100.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTrace and rare earth element (REE) analysis\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 32 bulk samples (avoiding large clasts in till samples) were analyzed on an Agilent 7700e ICP-MS at the Wuhan Sample Solution Analytical Technology Co. One mL of HNO\u003csub\u003e3\u003c/sub\u003e and 1 mL of HF were slowly added to 50 mg of sample powder (200 mesh) in a Teflon bomb, and the mixture was heated to 190 ℃ in an oven for \u0026gt;24 h (n.b., all utilized acids were high-purity laboratory-grade). After cooling, the Teflon bomb was opened and placed on a hotplate at 140 ℃ and evaporated to incipient dryness, and then 1 mL of HNO\u003csub\u003e3\u003c/sub\u003e was added and evaporated to dryness again. One mL of HNO\u003csub\u003e3\u003c/sub\u003e, 1 mL of MQ water, and 1 mL of an internal standard solution comprising 1 ppm In were added, and the Teflon bomb was resealed and placed in the oven at 190 ℃ for \u0026gt;12 h. The final solutions were transferred to polyethylene bottles and diluted to 100 g via addition of 2% HNO\u003csub\u003e3\u003c/sub\u003e prior to ICP-MS analysis. The international rock standards RGM-2, GSR-3 and JA-2 were used to monitor analytical accuracy. Analytical precision was better than \u0026plusmn;5% for all elements based on international rock standards and replicate extractions. The results were listed in Supplementary Table 4, where Eu/Eu* = Eu\u003csub\u003eN\u003c/sub\u003e/(Sm\u003csub\u003eN\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e\u0026times;Tb\u003csub\u003eN\u003c/sub\u003e)\u003csup\u003e1/3\u003c/sup\u003e and the subscript N represents normalization to PAAS (Post-Archean Australian Shale).\u0026nbsp;\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research was supported by the National Science and Technology Major Project of China (2025ZD1008901) and National Natural Science Foundation of China (42276068, 42302215, and 42472374).\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRooney, AD, Strauss, JV, Brandon, AD \u0026amp; Macdonald, FA A Cryogenian chronology: Two long-lasting synchronous Neoproterozoic glaciations. \u003cem\u003eGeology\u003c/em\u003e \u003cstrong\u003e43\u003c/strong\u003e, 459\u0026ndash;462 (2015).\u003c/li\u003e\n\u003cli\u003eRooney, AD, Yang, C, Condon, DJ, Zhu, M \u0026amp; Macdonald, FA U-Pb and Re-Os geochronology tracks stratigraphic condensation in the Sturtian snowball Earth aftermath. \u003cem\u003eGeology\u003c/em\u003e \u003cstrong\u003e48\u003c/strong\u003e, 625\u0026ndash;629 (2020).\u003c/li\u003e\n\u003cli\u003eMa, X, Wang, J, Wang, Z, Algeo, TJ, Chen, C, Cen, Y, Yin, Q-Z, Huang, C, Xu, L, Huang, C \u0026amp; Chen, D Geochronological constraints on Cryogenian ice ages: Zircon U-Pb ages from a shelf section in South China. \u003cem\u003eGlob. Planet. Change\u003c/em\u003e \u003cstrong\u003e222\u003c/strong\u003e, 104071, https//doi.org/10.1016/j.gloplacha.2023.104071 (2023).\u003c/li\u003e\n\u003cli\u003eHoffmann, K-H, Condon, DJ, Bowring, SA \u0026amp; Crowley, JL U-Pb zircon date from the Neoproterozoic Ghaub Formation Namibia: Constraints on Marinoan glaciation. \u003cem\u003eGeology\u003c/em\u003e \u003cstrong\u003e32\u003c/strong\u003e, 817\u0026ndash;820 (2004).\u003c/li\u003e\n\u003cli\u003eCondon, D, Zhu, M, Bowring, S, Wang, W, Yang, A \u0026amp; Jin, Y U-Pb ages from the Neoproterozoic Doushantuo Formation, China. \u003cem\u003eScience\u003c/em\u003e \u003cstrong\u003e308\u003c/strong\u003e, 95\u0026ndash;98 (2005).\u003c/li\u003e\n\u003cli\u003eDong, Y, Hui, B, Sun, S, Sun, J, Zang, R, Zhang, B, Luo, Q, Chong, F, Yu, K, Fan, M, Li, Y, Li, Y, Zhu, X, Dai, Q \u0026amp; Zuo, Z The links between Neoproterozoic tectonics, paleoenvironment and Cambrian explosion in the Yangtze Block, China. \u003cem\u003eEarth Sci. Rev.\u003c/em\u003e \u003cstrong\u003e248\u003c/strong\u003e, doi.org/10.1016/j.earscirev.2023.104638 (2024).\u003c/li\u003e\n\u003cli\u003eKey, RM, Liyungu, AK, Njamu, FM, Somwe, V, Banda, J, Mosley, PN \u0026amp; Armstrong, RA The western arm of the Lufilian Arc in NW Zambia and its potential for copper mineralization. \u003cem\u003eJ. Afr. Earth Sci.\u003c/em\u003e \u003cstrong\u003e33\u003c/strong\u003e, 503\u0026ndash;528 (2001).\u003c/li\u003e\n\u003cli\u003eXu, B, Xiao, S, Zou, H, Chen, Y, Li, ZX, Song, B, Liu, D, Zhou, C \u0026amp; Yuan, X SHRIMP zircon U-Pb age constraints on Neoproterozoic Quruqtagh diamicities in NW China. \u003cem\u003ePrecambrian Res. \u003c/em\u003e\u003cstrong\u003e168\u003c/strong\u003e, 247\u0026ndash;258 (2009).\u003c/li\u003e\n\u003cli\u003eMacLennan, SA, Eddy, MP, Merschat, AJ, Mehra, A, Crockford, P, Maloof, AC, Southworth, CS \u0026amp; Schoene, B Geologic evidence for an icehouse Earth before the Sturtian global glaciation. \u003cem\u003eSci. Adv.\u003c/em\u003e \u003cstrong\u003e6\u003c/strong\u003e, eaay6647 (2020).\u003c/li\u003e\n\u003cli\u003eFrimmel, HE Neoproterozoic Gariep Orogen. in \u003cem\u003eThe Geology of Namibia\u003c/em\u003e: Volume \u003cstrong\u003e2\u003c/strong\u003e, Neoproterozoic to Lower Palaeozoic (ed. Miller, RM) 14.1\u0026ndash;14.39 (2008).\u003c/li\u003e\n\u003cli\u003ePu, JP, Macdonald, FA, Smith, EF, Ramezani, J \u0026amp; Swanson-Hysell, N Tonian basins record rifting of Kalahari from Rodinia and no evidence of a pre-Sturtian Kaigas glaciation. \u003cem\u003eEarth Planet. Sci. Lett.\u003c/em\u003e \u003cstrong\u003e624\u003c/strong\u003e, https//doi.org/10.1016/j.epsl.2023.118472 (2023).\u003c/li\u003e\n\u003cli\u003eMerdith, AS, Collins, AS, Williams, SE, Pisarevsky, S, Foden, JD, Archibald, DB, Blades, ML, Alessio, BL, Armistead, S, Plavsa, D, Clark, C \u0026amp; M\u0026uuml;ller, RD A full-plate global reconstruction of the Neoproterozoic.\u003cem\u003e Gondwana Res.\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e, 84\u0026ndash;134, https://doi.org/10.1016/j.gr.2017.04.001 (2017).\u003c/li\u003e\n\u003cli\u003ePark, Y, Swanson-Hysell, NL, Xian, H, Zhang, S, Condon, DJ, Fu, H \u0026amp; Macdonald, FA A consistently high-latitude South China from 820 to 780 Ma: implications for exclusion from Rodinia and the feasibility of large-scale true polar wander. \u003cem\u003eJ. Geophys. Res. Solid Earth\u003c/em\u003e \u003cstrong\u003e126\u003c/strong\u003e, https//doi.org/10.1029/2020jb021541 (2021).\u003c/li\u003e\n\u003cli\u003eChang, L, Zhang, S, Li, H, Xian, H, Wu, H \u0026amp; Yang, T New paleomagnetic insights into the Neoproterozoic connection between South China and India and their position in Rodinia. \u003cem\u003eGeophys. Res. Lett.\u003c/em\u003e \u003cstrong\u003e49\u003c/strong\u003e, https//doi.org/10.1029/2022gl098348 (2022).\u003c/li\u003e\n\u003cli\u003eLi, S, Li, X, Wang, G, Liu, Y, Wang, Z, Wang, T, Cao, X, Guo, X, Somerville, I, Li, Y, Zhou, J, Dai, L, Jiang, S, Zhao, H, Wang, Y, Wang, G \u0026amp; Yu, S Global Meso-Neoproterozoic plate reconstruction and formation mechanism for Precambrian basins: constraints from three cratons in China. \u003cem\u003eEarth Sci. Rev.\u003c/em\u003e \u003cstrong\u003e198\u003c/strong\u003e, 102946. doi.org/10.1016/j.earscirev.2019.102946 (2019)\u003c/li\u003e\n\u003cli\u003eLi, Z Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correlations with other continents: evidence for a mantle superplume that broke up Rodinia. \u003cem\u003ePrecambrian Res. \u003c/em\u003e\u003cstrong\u003e122\u003c/strong\u003e, 85\u0026ndash;109 (2003).\u003c/li\u003e\n\u003cli\u003eSong, G, Wang, X, Shi, X \u0026amp; Jiang, G New U-Pb age constraints on the upper Banxi Group and synchrony of the Sturtian glaciation in South China.\u003cem\u003e Geosci. Front.\u003c/em\u003e \u003cstrong\u003e8\u003c/strong\u003e, 1161\u0026ndash;1173 (2017).\u003c/li\u003e\n\u003cli\u003eXu, Y, Zhang, K, He, W, Yu, Y, Kou, X, Song, B, Luo, M, Wang, L, Ma, Z \u0026amp; Yang, F Tonian tectonic-strata regions and geological significance in China. \u003cem\u003eActa Geol. Sin. Engl. Edn.\u003c/em\u003e \u003cstrong\u003e94\u003c/strong\u003e, 914\u0026ndash;941 (2020)\u003c/li\u003e\n\u003cli\u003eLan, Z, Li, XH, Zhu, M, Zhang, Q \u0026amp; Li, Q-L Revisiting the Liantuo Formation in Yangtze Block, South China: SIMS U-Pb zircon age constraints and regional and global significance. \u003cem\u003ePrecambrian Res.\u003c/em\u003e \u003cstrong\u003e263\u003c/strong\u003e, 123\u0026ndash;141 (2015).\u003c/li\u003e\n\u003cli\u003eHe, Y-Y, Niu, Z-J, Song, F \u0026amp; Yang, W-Q Geological characteristics and stratigraphic correlation of the Neoproterozoic Dayaogu Formation of the Lengjiaxi Group in Southern Hubei Province.\u003cem\u003e J. Stratigr.\u003c/em\u003e \u003cstrong\u003e41\u003c/strong\u003e, 195\u0026ndash;208 (2017) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eSong, F, Niu, Z-J, Liu, H, He, Y-Y \u0026amp; Yang, W-Q Stratigraphic sequence and contact relationship of the Nanhua system in South-Eastern Hubei Province: a key to the stratigraphic correlation between the inner Yangtze region and the south-eastern basin. \u003cem\u003eJ. Stratigr.\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 251\u0026ndash;260 (2016) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eRubatto, D Zircon trace element geochemistry: partitioning with garnet and the link between U-Pb ages and metamorphism. \u003cem\u003eChem. Geol.\u003c/em\u003e \u003cstrong\u003e184\u003c/strong\u003e, 123\u0026ndash;128 (2002).\u003c/li\u003e\n\u003cli\u003eNing, K, Deng, Q, Cui, X, Wang, Z, Ren, G \u0026amp; Yang, Q Zircon U-Pb age and stratigraphic significance of the tuff from the lowermost Liantuo Formation in the Dahongshan area of the northern Yangtze Block. \u003cem\u003eGeol. Bull. China\u003c/em\u003e \u003cstrong\u003e43\u003c/strong\u003e, 363\u0026ndash;375 (2024) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eMa, X, Wang, J, Algeo, TJ, Wang, Z, Cen, Y, Chen, C, Chen, D, Lu, J \u0026amp; Yang, Y U-Pb dating of detrital zircons from the Datangpo Formation, South China: Implications for Sturtian deglaciation age and Nanhua stratal provenance. \u003cem\u003ePalaeogeogr. Palaeoclimatol. Palaeoecol.\u003c/em\u003e \u003cstrong\u003e617\u003c/strong\u003e, 111494, https//doi.org/10.1016/j.palaeo.2023.111494 (2023).\u003c/li\u003e\n\u003cli\u003eLan, Z, Huyskens, MH, Lu, K, Li, X-H, Zhang, G, Lu, D \u0026amp; Yin, Q-Z Toward refining the onset age of Sturtian glaciation in South China. \u003cem\u003ePrecambrian Res. \u003c/em\u003e\u003cstrong\u003e338\u003c/strong\u003e, doi.org/10.1016/j.precamres.2019.105555 (2020).\u003c/li\u003e\n\u003cli\u003eGao, S, Luo, TC, Zhang, BR, Zhang, HF, Han, YW, Zhao, ZD \u0026amp; Hu, YK Chemical composition of the continental crust as revealed by studies in East China. \u003cem\u003eGeochim. Cosmochim. Acta\u003c/em\u003e \u003cstrong\u003e62\u003c/strong\u003e, 1959\u0026ndash;1975 (1998).\u003c/li\u003e\n\u003cli\u003eGarzanti, E, Padoan, M, Setti, M, Najman, Y, Peruta, L \u0026amp; Villa, IM Weathering geochemistry and Sr-Nd fingerprints of equatorial upper Nile and Congo muds. \u003cem\u003eGeochem. Geophys. Geosyst.\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 292\u0026ndash;316 (2013).\u003c/li\u003e\n\u003cli\u003eWang, Y, Kuang, H, Liu, Y, Zhao, F, Peng, N, Chen, X, Qi, K, Liu, H, Wang, Z, Zhong, Q \u0026amp; Chen, J Sedimentary evolution from greenhouse to icehouse of Neoproterozoic and age constraints in the northern Yangtze Craton. \u003cem\u003eGlob. Planet. Change\u003c/em\u003e \u003cstrong\u003e227\u003c/strong\u003e, https//doi.org/10.1016/j.gloplacha.2023.104179 (2023).\u003c/li\u003e\n\u003cli\u003eMenzies, J, van der Meer, JJM \u0026amp; Ravier, E A kinematic unifying theory of microstructures in subglacial tills. \u003cem\u003eSediment. Geol.\u003c/em\u003e \u003cstrong\u003e344\u003c/strong\u003e, 57\u0026ndash;70, https//doi.org/10.1016/j.sedgeo.2016.03.024 (2016).\u003c/li\u003e\n\u003cli\u003eTembe, S, Lockner, DA \u0026amp; Wong, T-F Effect of clay content and mineralogy on frictional sliding behavior of simulated gouges: binary and ternary mixtures of quartz, illite, and montmorillonite.\u003cem\u003e J. Geophys. Res.\u003c/em\u003e \u003cstrong\u003e115\u003c/strong\u003e, B03416 (2010).\u003c/li\u003e\n\u003cli\u003eMenzies, J \u0026amp; Ellwanger, D Insights into subglacial processes inferred from the micromorphological analyses of complex diamicton stratigraphy near Illmensee-Lichtenegg, Hochsten, Germany.\u003cem\u003e Boreas\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 271\u0026ndash;288, https//doi.org/10.1111/j.1502-3885.2010.00194.x (2010).\u003c/li\u003e\n\u003cli\u003eWang, Y, Kuang, H, Liu, Y, Zhao, F, Peng, N, Chen, X, Qi, K, Liu, H \u0026amp; Dong, G Chronological framework and sedimentary evolution process of the Neoproterozoic Liantuo Formation in the Yangtze Craton. \u003cem\u003eActa Geol. Sin. \u003c/em\u003e\u003cstrong\u003e97\u003c/strong\u003e, 3922\u0026ndash;3952 (2023) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eMa, G, Li, H \u0026amp; Zhang, Z An investigation of the age limits of the Sinian System in South China. Bull. Yichang Inst. Geol. Miner. Resour. Chin.\u003cem\u003e Acad. Geol. Sci. \u003c/em\u003e\u003cstrong\u003e6\u0026ndash;34\u003c/strong\u003e (1984) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eGao, LZ, Lu, JP, Ding, XZ, Wang, HR, Liu, YX \u0026amp; Li, J Zircon U-Pb dating of Neoproterozoic tuff in South Guangxi and its implications for stratigraphic correlation. \u003cem\u003eGeol. China\u003c/em\u003e \u003cstrong\u003e40\u003c/strong\u003e, 1443\u0026ndash;1452 (2013) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eYin, CY \u0026amp; Gao, LZ Definition, time limit and stratigraphic subdivision of the Nanhuan System in China.\u003cem\u003e J. Stratigr.\u003c/em\u003e\u003cstrong\u003e37\u003c/strong\u003e, 534\u0026ndash;541 (2013) (in Chinese with English abstract).\u003c/li\u003e\n\u003cli\u003eZhang, S, Jiang, G, Dong, J, Han, Y \u0026amp; Wu, H New SHRIMP U-Pb age from the Wuqiangxi Formation of Banxi Group: Implications for rifting and stratigraphic erosion associated with the early Cryogenian (Sturtian) glaciation in South China. \u003cem\u003eSci. China Ser. D Earth Sci. \u003c/em\u003e\u003cstrong\u003e51\u003c/strong\u003e, 1537\u0026ndash;1544, doi.org/10.1007/s11430-008-0119-z (2008).\u003c/li\u003e\n\u003cli\u003eNesbitt, HW \u0026amp; Young, GM Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. \u003cem\u003eNature\u003c/em\u003e \u003cstrong\u003e299\u003c/strong\u003e, 715\u0026ndash;717 (1982).\u003c/li\u003e\n\u003cli\u003eChen, C, Wang, J, Wang, Z, Peng, Y, Chen, X, Ma, X, Cen, Y, Zhao, J \u0026amp; Zhou, P Variation of chemical index of alteration (CIA) in the Ediacaran Doushantuo Formation and its environmental implications. \u003cem\u003ePrecambrian Res.\u003c/em\u003e \u003cstrong\u003e347\u003c/strong\u003e, 105829 (2020).\u003c/li\u003e\n\u003cli\u003eChen, C, Wang, J, Chen, X, Algeo, TJ, Wang, Z, Yang, W \u0026amp; Song, Q Productivity and redox influences on the late Ordovician \u0026lsquo;Katian Extinction\u0026rsquo; and \u0026lsquo;early Silurian Recovery\u0026rsquo;. \u003cem\u003ePalaeogeogr. Palaeoclimatol. Palaeoecol.\u003c/em\u003e \u003cstrong\u003e642\u003c/strong\u003e. doi.org/10.1016/j.palaeo.2024.112176. (2024)\u003c/li\u003e\n\u003cli\u003ePrice, JR \u0026amp; Velbel, MA Chemical weathering indices applied to weathering profiles developed on heterogeneous felsic metamorphic parent rocks. \u003cem\u003eChem. Geol.\u003c/em\u003e \u003cstrong\u003e202\u003c/strong\u003e, 397\u0026ndash;416 (2003).\u003c/li\u003e\n\u003cli\u003eAlgeo, TJ, Hong, H \u0026amp; Wang, C The chemical index of alteration (CIA) and interpretation of ACNK diagrams. \u003cem\u003eChem. Geol.\u003c/em\u003e\u003cstrong\u003e 671\u003c/strong\u003e, https://doi.org/10.1016/j.chemgeo.2024.122474 (2025).\u003c/li\u003e\n\u003cli\u003eGuo, Y, Yang, S, Su, N, Li, C, Yin, P \u0026amp; Wang, Z Revisiting the effects of hydrodynamic sorting and sedimentary recycling on chemical weathering indices. \u003cem\u003eGeochim. Cosmochim. Acta \u003c/em\u003e\u003cstrong\u003e227\u003c/strong\u003e, 48\u0026ndash;63 (2018).\u003c/li\u003e\n\u003cli\u003eParker, A An index of weathering for silicate rocks. \u003cem\u003eGeol. Mag.\u003c/em\u003e \u003cstrong\u003e107\u003c/strong\u003e, 501\u0026ndash;504 (1970).\u003c/li\u003e\n\u003cli\u003eMcLennan, SM Weathering and global denudation. \u003cem\u003eJ. Geol.\u003c/em\u003e \u003cstrong\u003e101\u003c/strong\u003e, 295\u0026ndash;303 (1993).\u003c/li\u003e\n\u003cli\u003eHong, H, Zhao, L, Fang, Q, Algeo, TJ, Wang, C, Yu, J, Gong, N, Yin, K \u0026amp; Ji, K Volcanic sources and diagenetic alteration of Permian-Triassic boundary K-bentonites in Guizhou Province, South China. \u003cem\u003ePalaeogeogr. Palaeoclimatol. Palaeoecol.\u003c/em\u003e \u003cstrong\u003e519\u003c/strong\u003e, 141\u0026ndash;153 (2019).\u003c/li\u003e\n\u003cli\u003evan de Kamp, PC Potassium distribution and metasomatism in pelites and schists: how and when, relation to postdepositional events.\u003cem\u003e J. Sediment. Res.\u003c/em\u003e \u003cstrong\u003e86\u003c/strong\u003e, 683\u0026ndash;711 (2016).\u003c/li\u003e\n\u003cli\u003eFedo, CM, Nesbitt, HW, Young, GM Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleoweathering conditions and provenance.\u003cem\u003e Geology\u003c/em\u003e \u003cstrong\u003e23\u003c/strong\u003e (10), 921\u0026ndash;924 (1995)\u003c/li\u003e\n\u003cli\u003eWang, C Metallogenic characteristics and prospective prediction of Dahaoshan gold deposit in the north Jiangxi province. \u003cem\u003eDoctoral thesis at China University of Geosciences-Wuhan \u003c/em\u003e(2017) (in Chinese with English abstract)\u003c/li\u003e\n\u003cli\u003eHuang, J, Feng, L, Lu, D, Zhang, Q, Sun, T \u0026amp; Chu, X Multiple climate cooling prior to Sturtian glaciations: Evidence from chemical index of alteration of sediments in South China.\u003cem\u003e Sci. Rep.\u003c/em\u003e \u003cstrong\u003e4\u003c/strong\u003e, 6868 (2014).\u003c/li\u003e\n\u003cli\u003eGu, Z, Jian, X, Liu, G, Shen, X, Fu, H, Zhai, X \u0026amp; Jiang, H Age, provenance and tectonic setting of the Tonian-Cryogenian clastic successions in the northwest Bikou terrane, NW Yangtze Block, Central China. \u003cem\u003ePrecambrian Res.\u003c/em\u003e \u003cstrong\u003e397\u003c/strong\u003e, https//doi.org/10.1016/j.precamres.2023.107197 (2023).\u003c/li\u003e\n\u003cli\u003eDehler, CM, Schmitz, M, Bullard, A, Porter, S, Timmons, M, Karlstrom, K \u0026amp; Cothren, H Precise U-Pb age models refine Neoproterozoic western Laurentian rift initiation, correlation, and Earth system changes. \u003cem\u003ePrecambrian Res.\u003c/em\u003e \u003cstrong\u003e396\u003c/strong\u003e, https//doi.org/10.1016/j.precamres.2023.107156 (2023).\u003c/li\u003e\n\u003cli\u003eTrower, EJ, Gutoski, JR, Wala, VT, Mackey, TJ \u0026amp; Simpson, C Tonian Low-Latitude Marine Ecosystems Were Cold Before Snowball Earth. \u003cem\u003eGeophysical Research Letters\u003c/em\u003e \u003cstrong\u003e50\u003c/strong\u003e (5). doi.org/10.1029/2022gl101903. (2023)\u003c/li\u003e\n\u003cli\u003eTrower, EJ, Ingalls, M, Gutoski, JR, \u0026amp; Wala, VT New constraints on phosphate concentration and temperature in shallow late Tonian seawater. \u003cem\u003eGeology\u003c/em\u003e doi.org/10.1130/g53532.1. (2025)\u003c/li\u003e\n\u003cli\u003eHu, Z, Zhang, W, Liu, Y, Gao, S, Li, M, Zong, K, Chen, H \u0026amp; Hu, S \u0026quot;Wave\u0026quot; signal-smoothing and mercury-removing device for laser ablation quadrupole and multiple collector ICPMS analysis: application to lead isotope analysis. \u003cem\u003eAnal. Chem.\u003c/em\u003e \u003cstrong\u003e87\u003c/strong\u003e, 1152\u0026ndash;1157 (2014).\u003c/li\u003e\n\u003cli\u003eZong, K, Klemd, R, Yuan, Y, He, Z, Guo, J, Shi, X, Liu, Y, Hu, Z \u0026amp; Zhang, Z The assembly of Rodinia: the correlation of early Neoproterozoic (ca. 900 Ma) high-grade metamorphism and continental arc formation in the southern Beishan Orogen, southern Central Asian Orogenic Belt (CAOB). \u003cem\u003ePrecambrian Res.\u003c/em\u003e \u003cstrong\u003e290\u003c/strong\u003e, 32\u0026ndash;48 (2017).\u003c/li\u003e\n\u003cli\u003eLiu, Y, Hu, Z, Gao, S, Gunther, D, Xu, J, Gao, C \u0026amp; Chen, H In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard. \u003cem\u003eChem. Geol.\u003c/em\u003e \u003cstrong\u003e257\u003c/strong\u003e, 34\u0026ndash;43 (2008).\u003c/li\u003e\n\u003cli\u003eGao, J, Feng, Q, Zhang, X, Zhou, L, Jiao, Z \u0026amp; Qin, Y Zircon U-Pb geochronology of crystal tuff on Lingshan Island and its geological implications for magmatism, stratigraphic age and geological events.\u003cem\u003e Sci. Rep. \u003c/em\u003e\u003cstrong\u003e8\u003c/strong\u003e, https://doi.org/10.1038/s41598-018-30060-1 (2018).\u003c/li\u003e\n\u003cli\u003eLachance, GR \u0026amp; Claisse, F Quantitative X-ray Fluorescence Analysis Theory and Application. \u003cem\u003eJohn Wiley \u0026amp; Sons\u003c/em\u003e (1995).\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":"[email protected]","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":"","lastPublishedDoi":"10.21203/rs.3.rs-7658226/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7658226/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Paleoclimatic conditions during the Tonian Period (~1000-720 Ma), preceding the Cryogenian Snowball Earth glaciations, remain ambiguous. While the apparent paucity of glacially influenced sedimentary rocks suggests a stable and dominantly ice-free climate during the late Tonian, several pre-Sturtian glacial deposits have been tentatively identified. To investigate climatic conditions leading up to the Cryogenian, we present glacial till depositions in Tonian from four outcrops in the Tongshan, South China, along with geochemical and geochronologic data from one of these sites, revealing significant regional climatic shifts during the Tonian period. This glacial till deposition is constrained older than 745.3 Ma from zircon age and is constrained in 792.1–773 Ma through stratigraphic correlation. In addition, another climatic cooling at ~750 Ma, although with no clear sedimentological evidence, is evidenced by decreased weathering proxy. This climatic cooling may have been correlated with the glaciolacustrine deposits of the Konnarock Formation in southwestern Virginia, USA. Our findings thus reveal the existence of at least two cold climate intervals during the late Tonian Period, thereby providing novel insights into the evolution of global climate conditions in advance of the Cryogenian Snowball Earth.","manuscriptTitle":"Tonian glaciation in South China","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-10 10:21:06","doi":"10.21203/rs.3.rs-7658226/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","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":"1273e318-2c88-434b-9e71-8976f1326a8b","owner":[],"postedDate":"October 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":55508431,"name":"Earth and environmental sciences/Solid Earth sciences/Geology/Precambrian geology"},{"id":55508432,"name":"Earth and environmental sciences/Climate sciences/Palaeoclimate"},{"id":55508433,"name":"Earth and environmental sciences/Solid Earth sciences/Geology"}],"tags":[],"updatedAt":"2025-11-07T15:31:41+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-10 10:21:06","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7658226","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7658226","identity":"rs-7658226","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}