Control of shelf width on submarine canyon formation along the central Algerian margin

Control of shelf width on submarine canyon formation along the central Algerian margin | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Control of shelf width on submarine canyon formation along the central Algerian margin nadia amarni, lounes fernane, ryhane lounas This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9129667/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 Erosive dynamics in deep marine environments are strongly controlled by the morphology of the continental shelf, particularly along active margins. On the central Algerian margin, where shelf width varies laterally, submarine incision manifests through the co-development of deeply incised canyons and dense gully networks. This study investigates how shelf width influences the formation, spatial distribution, and evolution of these erosive features, based on high-resolution bathymetric data acquired during the MARADJA 1 cruise (2003) and through detailed morphometric analyses. The results reveal that in areas where the continental shelf is narrow (5_20 km), gravitational processes are highly focused, promoting the development of deeply incised canyons characterized by steep slopes, smooth longitudinal profiles, and hierarchical drainage networks. Conversely, wider shelf areas (30_40 km) facilítate a gradual dissipation of sedimentary energy, leading to the formation of dense but shallow gully networks, organized in a less hierarchical pattern. The spatial distribution of these erosive forms suggests that shelf width acts as a morphological filter, controlling sediment transfer pathways to the slope and deep basin. These findings provide new insights into the geomorphological processes shaping the evolution of continental margins and highlight the critical role of morphological parameters in modeling sediment transfer and assessing associated geological hazards, such as submarine landslides and tsunamis. Central Algerian margin Continental shelf Submarine canyons Submarine gullies Sediment dynamics. Figures Figure 1 Figure 2 Figure 3 1. Introduction Continental margins constitute critical transitional domains between terrestrial environments and the deep ocean. Within these zones, tectonic activity, sedimentary dynamics, oceanographic circulation, and biological processes converge and interact in complex ways. As highly dynamic systems, continental margins regulate the transfer of sediment, nutrients, organic matter, and energy from continental sources to oceanic basins. Through these exchanges, they exert a strong influence on seafloor morphology, biogeochemical cycling, and the structure and functioning of deep-marine ecosystems (Fildani, 2017 ; Harris and Whiteway, 2011 ; Nittrouer and Wright, 1994 ). Among the most distinctive geomorphological features of continental margins are submarine canyons. These deeply incised valleys cut across the continental shelf and slope, forming major conduits for sediment transport from shallow coastal areas to the deep sea. Beyond their striking morphology, submarine canyons represent fundamental structural and functional components of marine sedimentary systems. Submarine canyons are now widely recognized as preferential pathways for the gravity-driven transfer of sediments, organic matter, nutrients, and, in some cases, pollutants from coastal and neritic environments to deep ocean basins (Fernandez-Arcaya et al., 2017 ; Harris and Whiteway, 2011 ; Puig et al., 2014). By maintaining both vertical and longitudinal connectivity, submarine canyons function as dynamic links between continental, coastal, and deep-marine environments. They regulate sediment redistribution across continental margins and enhance exchanges between shallow and deep systems. Beyond their sedimentary significance, their complex geomorphology influences deep-sea ecological processes by promoting the accumulation of organic matter, thereby sustaining diverse and productive benthic communities. Scientific recognition of submarine canyons began in the early twentieth century, when early bathymetric surveys revealed deeply incised valleys beneath sea level. In 1903, Joseph William Spencer proposed a subaerial fluvial origin linked to low sea-level stands. The pioneering work of Francis Parker (Shepard, 1981 ; Shepard, 1965 ) advanced this field by highlighting both the morphological similarities with continental canyons and the role of distinct marine processes in their formation. More recently, advances in multibeam bathymetry and seismic imaging have enabled high-resolution global mapping, revealing thousands of submarine canyons distributed along active and passive margins worldwide (Amblas et al., 2017 ; Harris and Whiteway, 2011 ). Submarine canyons are defined as sinuous valleys with steep walls, V-shaped cross sections, and longitudinal profiles sloping seaward (Shepard, 1965 ). Their morphology exhibits considerable variability in form, size, and degree of incision, reflecting the combined influence of tectonic setting, sediment characteristics, and the intensity of hydro-sedimentary processes (Covault et al., 2011 ; Farre et al., 1983 ; Pratson and Coakley, 1996 ). Global morphometric analyses reveal clear contrasts between canyons on active margins—typically narrower and more deeply incised—and those on passive margins, which are generally broader and less deeply entrenched (Goff, 2001 ; Harris and Whiteway, 2011 ). The origin and long-term evolution of submarine canyons result from the interplay of processes operating across multiple spatial and temporal scales. Turbidity currents are a primary mechanism driving canyon incision and sediment transport to deep basins (Ewing and Heezen, 1952 ; Mulder et al., 2012 ; Normark and Carlson, 2003 ). These gravity-driven flows may be triggered by submarine landslides, extreme river floods, storms, dense water cascading from the continental shelf, or seismic activity (Nittrouer and Wright, 1994 ; Puig et al., 2014). Eustatic sea-level changes have also strongly influenced submarine canyon formation, with Quaternary lowstands promoting headward incision and enhancing connections to continental rivers, enabling direct sediment transfer to deep margins (Harris and Whiteway, 2011 ; Shepard, 1981 ). However, canyon evolution reflects the combined action of multiple processes, including retrogressive erosion, gravitational incision, tectonics, fluid seepage, and mass-wasting events (Daly, 1936 ; Harris and Whiteway, 2011 ; Mountjoy et al., 2009b ). Therefore, submarine canyons are dynamic systems shaped by both sea-level fluctuations and diverse geomorphic processes. Submarine canyons are typically classified based on head configuration and connectivity with river systems into three types : (i) shelf-incising canyons directly connected to rivers, (ii) shelf-incising canyons without direct fluvial connection, and (iii) slope-confined canyons (Harris and Whiteway, 2011 ). Morphological maturity provides a complementary classification, distinguishing dendritic, sinuous mature canyons from more linear, juvenile forms (Goff, 2001 ; Twichell and Roberts, 1982 ). Longitudinal profiles—concave, linear, or convex—offer insight into dominant processes and tectono-sedimentary context (Covault et al., 2011 ; Goff, 2001 ). Concave profiles are typical of highly erosive active margins, linear profiles of mature passive margins dominated by fluvial input, and convex profiles of tectonically uplifted margins. Beyond their geomorphological and sedimentary importance, submarine canyons support highly diverse and productive deep-sea ecosystems. Their complex topography enhances organic matter accumulation, bentho-pelagic exchanges, and habitat diversity, thereby sustaining cold-water corals and numerous deep-sea fishes (De Leo et al., 2020 ; Fernandez-Arcaya et al., 2017 )). In addition, submarine canyons contribute to global carbon cycling through the sequestration and long-term storage of organic carbon. The Algerian continental margin in the western Mediterranean is an ideal setting to study submarine canyons due to its complex morphology and tectonic framework, shaped by Africa–Eurasia convergence, Alpine inheritance, and active sedimentary processes. Bathymetric and seismic data reveal numerous canyons along the slope, particularly between Algiers and Boumerdès, characterized by pronounced relief and sinuous courses indicative of active erosion and deposition (Gennesseaux et al., 2017 ; Nabila and Sabah, 2021 ). Canyon morphology varies with shelf width: narrow shelves favor deeply incised canyons, while broader shelves produce more confined forms (Fernane, 2014 ; Fernane et al., 2022 ; Lounes, 2022 ). Overall, shelf geometry, slope gradient, and structural topography strongly influence canyon formation, though integrated studies along the Algerian margin remain limited. This study examines how continental shelf width influences the formation, evolution, and morphometry of submarine canyons along the central Algerian margin using high-resolution bathymetric data, aiming to improve the understanding of submarine incision processes in the western Mediterranean and to refine general models of submarine canyon evolution. 2. General Framework 2.1. Geographical Overview The central Algerian continental margin constitutes a geostrategically significant segment of the southern Mediterranean coastline. It is characterized by a complex geomorphological setting and pronounced tectonic activity resulting from the ongoing convergence between the African and Eurasian plates. This sector is bounded to the north by the deep Algerian Basin, part of the western Mediterranean Sea, and to the south by the Tellian Atlas, an active fold-and-thrust belt. Geographically, it extends from Tipaza in the west to Boumerdes in the east, encompassing the coastline of the capital city, Algiers, and covering approximately 400 km of shoreline (Fig. 1 ). In contrast to passive margins, the central Algerian margin is an active compressional margin. It is distinguished by a narrow and steep continental shelf, numerous structural lineaments, and intense crustal deformation associated with plate convergence. The contemporary morphology reflects this tectonic regime, displaying fault-controlled bathymetric features, slope instabilities, and submarine canyon systems shaped by both structural inheritance and morphodynamic processes. 2.2. Geological Overview Northern Algeria forms part of the Alpine belt known as the Maghrebian Chain. From south to north, this chain is subdivided into three principal structural domains: (1) the external domain, represented by the Tellian units, mainly composed of marls and calcareous sedimentary series; (2) the flysch domain, corresponding to sediments deposited in the Maghrebian Tethys and subsequently involved in subduction processes; and (3) the internal domain, consisting of a Hercynian basement partially overlain by its sedimentary cover, referred to as the Kabylian Dorsale, and interpreted as a remnant of the Alboran–Kabylian–Peloritani–Calabrian (AlKaPeCa) domain. According to (Domzig et al., 2006 ), the subsurface of the study area comprises Oligo-Miocene sedimentary deposits, flysch units, and locally volcanic formations. The coastal strip extending from Dellys to Damous crosses the internal zones of the Maghrebian Chain. Lithostratigraphic mapping of the Algiers region reveals a Mio–Plio–Quaternary sedimentary cover unconformably overlying a Paleozoic metamorphic basement (Fig. 2 ). This basement consists predominantly of schists, micaschists, gneisses, and granites, and is strongly tectonized, cropping out notably between the Chenoua and Algiers massifs. In the Dellys region, outcrops are largely dominated by olistostromes, flysch deposits, and Tellian marls. These formations are interpreted as evidence of large-scale gravitational sliding within the Oligo-Miocene Kabylian basin. They are unconformably overlain by post-orogenic Miocene deposits, locally intruded by Miocene volcanic products, including the basalts of Cap Djinet (Raymond, 1976 ). The sedimentary cover of the Algerian offshore has been documented in several studies (Auzende, 1978 ; Domzig et al., 2006 ; El-Robrini, 1986 ; Hsü et al., 1973 ; Medaouri, 2014 ; Medaouri et al., 2012 ). A major feature of this cover is the Messinian salt series (Upper Miocene), deposited in basin areas during the Messinian Salinity Crisis (5.96–5.32 Ma). This event involved a significant sea-level drop and one or more phases of Mediterranean desiccation, leading to intense margin erosion and the accumulation of substantial evaporitic deposits in the basins (Clauzon, 1982 ; Gargani and Rigollet, 2007 ; Rouchy et al., 2001 ). Following the Pliocene reflooding, Pliocene to Quaternary sediments were progressively deposited. The mechanical properties of the Messinian evaporites favor syn-sedimentary mobility and diapiric processes (Domzig et al., 2006 ). 2.3. Climatic and Hydrological Overview Algeria is predominantly characterized by a hot and arid climate, except along its northern coastal fringe, which experiences a Mediterranean-type climate. In coastal cities, winter temperatures typically range between 8°C and 15°C. By late spring, average temperatures reach approximately 25°C, rising to 28–30°C during July and August. The topographic configuration of the coastal relief strongly influences regional climatic conditions, particularly precipitation distribution and intensity. Rainfall exhibits marked spatial and temporal variability, with irregular and occasionally intense events. Data from the National Office of Meteorology (ONM) for the period 1986 to 2025 indicate an average annual precipitation of approximately 690 mm in coastal areas. This climate variability plays a crucial role in controlling geological and hydrological processes along northern Algeria’s coastal zones. The drainage network within the study area remains relatively underdeveloped. The main watersheds originate in the Tellian Atlas, with the most significant being, from west to east, Oued Mazafran, Oued Isser, and Oued Sébaou (Fig. 2 ). Toward the western sector of the study area, watershed areas decrease considerably, in some cases to less than 200 km², while average slopes increase to 4–5°. These geomorphological conditions favor the development of short, steep catchments characterized by episodic torrential flows, particularly during autumn and spring. During intense rainfall events, hyperpycnal flows may be generated, potentially playing a key role in sediment transport to adjacent coastal and marine environments. 3. Data and Methods The data set used in this study was acquired during the MARADJA 1 oceanographic survey in September 2003 (MARADJA: MARge Active el DJAzaïr, el Djazaïr = Algiers) on board the Suroît research vessel (IFREMER). Bathymetric and reflectivity data along the slope were obtained using a Kongsberg EM300 Simrad multibeam echosounder, whereas a Kongsberg EM1000 was used to acquire data along the continental platform. The Simrad EM300 is a 32-kHz multibeam system that allows an overall swath coverage of approximately six times the water depth, increasing with depth to a maximum width of 5000 m at 1000 m. Its vertical accuracy can reach 2 m for the central beam and its lateral resolution is at most approximately 25 m. Bathymetric information allows a precise study of seabed morphology, and backscatter data allow the analysis of variations in seabed reflectivity. The depth of multibeam coverage ranges from 60 to 2800 m. The data set allowed the production of a Digital Elevation Model at a spatial resolution of 25 m ( Fig. 2 ). To delineate the boundaries of submarine canyons and gullies within the study area, a manual digitization approach was employed. This method integrates geomorphometric analysis, GIS-based processing, and morphological classification based on parameters such as size, depth, and degree of incision. The distinction between submarine canyons and gullies was based on morphometric criteria defined by (Harris and Whiteway, 2011). Two conditions must be simultaneously met for a feature to be classified as a submarine canyon: (I) The incision of the canyon head relative to the surrounding interfluves must exceed 100 meters; (II) The depth difference between the canyon head and its foot must be greater than 1000 meters. If either of these conditions is not satisfied, the feature is classified as a submarine gully. Additional morphometric parameters were also considered to further characterize the identified features. These include the width of the continental shelf, the total length of canyons and gullies, as well as the depth at the canyon head. These indicators provide valuable insights into the geometry, spatial organization, and degree of development of the submarine incision systems within the study area. 4. Results The morphological analysis of the central Algerian margin highlights a clear lateral segmentation of the shelf–slope system ( Fig. 3 ). Three morpho-structural sectors were distinguished: (i) an eastern sector between Cap Matifou and Tigzirt; (ii) a central sector encompassing the Bay of Bou Ismaïl and the Bay of Algiers; (iii) a western sector extending between Cap Chenoua and Cap Ténès. This spatial organization reveals a direct relationship between the width of the continental shelf, the morphology of the adjacent coastline, and the degree of development and formation of submarine canyons. Eastern sector: characterized by a narrow shelf with strong slope incision: The eastern sector is characterized by a narrow continental shelf (< 20 km), directly bordered by elevated coastal massifs (Thenia and Dellys massifs). The shelf–slope transition is abrupt, with slopes locally exceeding 10–15%. The slope is deeply incised by a dense network of submarine canyons sensu stricto, organized into hierarchical systems with multiple tributaries. These canyons include, from east to west, the Dellys Canyon, the Sebaou Canyon, and the Algiers Canyon. Canyon heads are located in close proximity to the shelf break, and several systems extend to the deep basin, indicating efficient sediment transport. The high density of incisions, their depth, and their longitudinal continuity suggest (i) sustained sediment supply from short and steep catchments and (ii) concentration of sediment fluxes at the shelf edge. The geometric configuration of the shelf therefore promotes sediment bypass and long-term slope incision. Central sector: wide shelf with limited incision: In contrast, the central sector displays a markedly wider continental shelf (> 30–40 km), developed offshore from low-relief coastal plains (Mitidja Plain). Submarine incision is weakly developed. The observed forms correspond predominantly to shallow, rectilinear gullies lacking hierarchical organization and confined to the upper slope or shelf edge. Their spatial distribution is discontinuous, and their longitudinal extent remains limited. The absence of mature canyons suggests lateral dispersion of sediment supply across the widened shelf, thereby reducing flow focusing at the slope. Thus, the wide shelf acts as a zone of sediment accommodation and dissipation, limiting the development of deep incisions. Western sector: very narrow shelf with strong incision: In the western sector, the continental shelf narrows again (5–10 km) and is bordered by steep coastal massifs (Ténès Massif). The slope exhibits steep gradients approaching 20 % and high morphological roughness. Numerous submarine canyons are developed in this sector, including the Gouraya Canyon and the Chlef Canyon. They display predominantly linear to sub-linear courses, steep interfluves, and locally stepped longitudinal profiles. The very strong incision observed in this sector reflects: (i) concentration of gravity-driven flows; (ii) structural and lithological control; (iii) enhanced efficiency of continent–basin coupling. Regional Controls on Canyon Distribution Comparison of the three sectors highlights a first-order morphological control exerted by continental shelf width and coastal physiography. Two principal configurations emerge: Narrow shelf + coastal massifs (eastern and western sectors) → high canyon density, deep incision, concentrated sediment transfer. Wide shelf + coastal plains (central sector) → limited incision, predominance of gullies, dispersed sediment fluxes. These results indicate that shelf width modulates sediment flux focusing at the continental margin, conditioning the transition from a morphology dominated by gullies to one dominated by well-developed submarine canyons. At the regional scale, the central Algerian margin thus appears segmented according to a morphodynamic gradient controlled by margin geometry, adjacent continental relief, and structural inheritance. 5. Discussion The results obtained along the central Algerian margin clearly highlight a first-order morphological control exerted by continental shelf width on the genesis, organization, and degree of maturity of submarine incision systems. Although this relationship has been suggested in several global studies, it appears particularly structuring at the regional scale, where lateral segmentation of the margin corresponds to marked contrasts between domains dominated by deeply incised canyons and sectors characterized by weakly developed gullies. The eastern and western sectors, characterized by narrow shelves (5–20 km), exhibit a high density of deeply incised canyons with predominantly concave to sublinear longitudinal profiles. This configuration is consistent with observations from the Gulf of Béjaïa and the western Algerian margin (Dahra margin), where incision is also associated with reduced shelf width and steep slopes (Fernane, 2014 ; Fernane et al., 2022 ; Lounes, 2022 ; Nabila and Sabah, 2021 ). In contrast, the central sector (Bay of Algiers – Bay of Bou Ismaïl), marked by a wider shelf (> 30–40 km), displays limited incision dominated by weakly hierarchical gullies. This organization is consistent with models proposed for relatively more stable portions of the western Algerian margin, where lateral dissipation of sediment flux reduces the focusing of gravity-driven flows (Aïdi et al., 2018 ; Domzig et al., 2006 ). At the scale of the Algerian margin, our results confirm that shelf width acts as a morphodynamic filter controlling the transition from a regime of concentrated sediment bypass (narrow shelf) to a regime of accommodation and storage (wide shelf). This dynamic occurs within an active compressive tectonic context related to Africa–Eurasia convergence, which enhances slope gradients and promotes gravitational instability (Bouyahiaoui et al., 2015 ). At the scale of the western Mediterranean, comparable results have been described along the Catalan margin and the Gulf of Lion, where deeply incised canyons are associated with relatively narrow shelves and active fluvial systems (Amblas et al., 2017 ; Puig et al., 2014). Similarly, on the Sardinian margin recently studied by (Caradonna et al., 2025 ), canyon morphology shows a strong correlation between shelf geometry and incision style. Sectors with narrow shelves display canyons efficiently connected to the deep basin, whereas wider shelves favor the development of shallow gully networks. The central Algerian margin therefore fits well within the Mediterranean model of active margins characterized by strong morphological segmentation, where lateral variability in shelf width modulates the intensity of continent–basin coupling. At the global scale, (Harris and Whiteway, 2011 ) demonstrated that canyons along active margins are generally shorter, narrower, and more deeply incised than those developed along passive margins. The characteristics observed in the eastern and western sectors of the Algerian margin are consistent with this model, with steep slopes and pronounced incision. Comparable observations have been reported offshore California and Chile, where narrow continental shelves associated with compressive margins favor the development of canyons deeply connected to abyssal basins (Covault et al., 2011 ; Mountjoy et al., 2009a ). In contrast, along passive margins such as the northwestern Atlantic margin, wide shelves and gentler slopes favor broader canyons with less abrupt profiles, often dominated by sediment reworking processes rather than intense gravitational incision (Pratson and Coakley, 1996 ). Our results therefore confirm that shelf width constitutes a key morphometric parameter, although its effect is amplified or modulated by tectonic setting, slope gradient, lithological nature, and sediment supply. The differences observed among the three sectors of the central Algerian margin suggest two contrasting morphodynamic regimes: Concentrated transfer regime (narrow shelf) : high gravitational energy, sustained incision, efficient connection to the deep basin, and increased potential for turbidity currents and submarine landslides. Lateral dissipation regime (wide shelf) : temporary sediment storage, dispersion of sediment flux, and incision largely restricted to the upper slope. These findings are consistent with sediment transfer models proposed by (Fildani, 2017 ), according to which margin geometry controls source-to-sink connectivity and the frequency of gravity-driven events. From a geological hazard perspective, sectors characterized by narrow shelves may present increased susceptibility to gravitational instabilities and submarine-generated tsunamis, consistent with regional analyses conducted after the Boumerdès earthquake (Aïdi et al., 2018 ). 6. Conclusion Continental shelf width is a key factor controlling the development, organization, and maturity of submarine incision systems along the central Algerian margin. Narrow shelves (5–20 km) are associated with deeply incised, hierarchically organized canyons and concentrated sediment transfer, while wide shelves (> 30 km) favor shallow gullies, lateral sediment dispersion, and limited slope incision. Shelf width interacts with slope gradient, tectonic compression, structural inheritance, and sediment supply to determine whether submarine systems evolve into mature, basin-connected canyons or remain confined as gullies. These insights have both scientific and applied significance: narrow-shelf sectors are prone to slope instability, submarine landslides, and tsunami hazards. Integrating morphometric parameters into sediment transfer and hazard models is therefore essential. Overall, this study highlights the fundamental role of margin geometry in shaping canyon–gully systems and provides a framework for future research combining bathymetry, seismic data, and numerical modeling to better understand source-to-sink dynamics and predict the evolution of active continental margins. Declarations Author Contribution Author Contributions All authors contributed significantly to the development of this work.[Author 1: Nadia Amarni]: Conceptualization, Data Collection, Formal Analysis, Writing – Original Draft.[Author 2: Lounes Fernane]: Supervision, Methodology.[Author 3: Ryhane Lounas]: Review and Editing, Validation.All authors have read and approved the final version of the manuscript. References Aïdi, C., Beslier, M.-O., Yelles-Chaouche, A.K., Klingelhoefer, F., Bracene, R., Galve, A., Bounif, A., Schenini, L., Hamai, L. and Schnurle, P.J.T., 2018. 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Rouchy, J., Orszag-Sperber, F., Blanc-Valleron, M.-M., Pierre, C., Rivière, M., Combourieu-Nebout, N. and Panayides, I.J.S.G., 2001. Paleoenvironmental changes at the Messinian–Pliocene boundary in the eastern Mediterranean (southern Cyprus basins): significance of the Messinian Lago-Mare. 145(1-2): 93-117. Shepard, F.P.J.A.b., 1981. Submarine canyons: multiple causes and long-time persistence. 65(6): 1062-1077. Shepard, F.P.J.P.i.o., 1965. Importance of submarine valleys in funneling sediments to the deep sea. 3: 321-332. Twichell, D.C. and Roberts, D.G.J.G., 1982. Morphology, distribution, and development of submarine canyons on the United States Atlantic continental slope between Hudson arid Baltimore Canyons. 10(8): 408-412. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9129667","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":611622739,"identity":"14bcf86b-2bca-4861-968f-52d6001ab410","order_by":0,"name":"nadia amarni","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYNACAyA+zMD4GMxhZm4gWguzMZjFzEiMFhA4wMAmDdFMQAv/tMPPPhcU3JHnO878rLqg4k80fztQy4+KbTi1SNxOM549w+CZ4czDbGa3Z5wxyJ1xmLGBsefMbdzW3E4wZuYxOMy44TCD2W3eNoPcBqAWZsY23Frkb6d/Bmmx33CY/VsxSMt8QloMbueAbUnccJjHjBmkZQMhLYa3c4pBWpJnHuYpluY5Y5y7EajlID6/yN1O38zM8+ewbd/54xs/81TI5c47f/jggx8VeLyPFRwgUf0oGAWjYBSMAjQAAMnrWCwDfaA1AAAAAElFTkSuQmCC","orcid":"","institution":"Houari Boumedienne University","correspondingAuthor":true,"prefix":"","firstName":"nadia","middleName":"","lastName":"amarni","suffix":""},{"id":611622740,"identity":"06a2b11d-254f-4009-a5c9-7d370979812e","order_by":1,"name":"lounes fernane","email":"","orcid":"","institution":"Higher National School of Marine Sciences and Coastal Management. Dely Ibrahim, Bois des Cars University Campus","correspondingAuthor":false,"prefix":"","firstName":"lounes","middleName":"","lastName":"fernane","suffix":""},{"id":611622741,"identity":"8a41813c-a886-45f2-8cb8-4f3473ba09a7","order_by":2,"name":"ryhane lounas","email":"","orcid":"","institution":"University of Las Palmas de Gran Canaria (ULPGC)","correspondingAuthor":false,"prefix":"","firstName":"ryhane","middleName":"","lastName":"lounas","suffix":""}],"badges":[],"createdAt":"2026-03-15 15:23:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9129667/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9129667/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105565637,"identity":"220cab31-1768-4897-abae-90737aaee26a","added_by":"auto","created_at":"2026-03-27 12:53:53","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":779011,"visible":true,"origin":"","legend":"\u003cp\u003eGeographical map of the study area.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9129667/v1/c148d472602761335811f41f.png"},{"id":105443589,"identity":"4aa5bd0c-277c-4787-8d54-0a623b5c9629","added_by":"auto","created_at":"2026-03-26 06:42:29","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":627445,"visible":true,"origin":"","legend":"\u003cp\u003eGeological map of the study area and associated bathymetric datasets.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9129667/v1/16af7b4911c74f54bc60fe80.png"},{"id":105566584,"identity":"d40c3d90-9f5d-49ec-9831-1774caf2689f","added_by":"auto","created_at":"2026-03-27 12:56:45","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":518522,"visible":true,"origin":"","legend":"\u003cp\u003eDistribution of canyons and gullies based on the width of the continental shelf.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9129667/v1/3cf68e81369367759fa692e8.png"},{"id":105570182,"identity":"705c0370-e870-4d6b-8e82-cc01fa68465f","added_by":"auto","created_at":"2026-03-27 13:15:10","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2277279,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9129667/v1/6d52ae63-cc04-4e17-a321-26c7f6655939.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Control of shelf width on submarine canyon formation along the central Algerian margin","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eContinental margins constitute critical transitional domains between terrestrial environments and the deep ocean. Within these zones, tectonic activity, sedimentary dynamics, oceanographic circulation, and biological processes converge and interact in complex ways. As highly dynamic systems, continental margins regulate the transfer of sediment, nutrients, organic matter, and energy from continental sources to oceanic basins. Through these exchanges, they exert a strong influence on seafloor morphology, biogeochemical cycling, and the structure and functioning of deep-marine ecosystems (Fildani, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Nittrouer and Wright, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1994\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAmong the most distinctive geomorphological features of continental margins are submarine canyons. These deeply incised valleys cut across the continental shelf and slope, forming major conduits for sediment transport from shallow coastal areas to the deep sea. Beyond their striking morphology, submarine canyons represent fundamental structural and functional components of marine sedimentary systems.\u003c/p\u003e \u003cp\u003eSubmarine canyons are now widely recognized as preferential pathways for the gravity-driven transfer of sediments, organic matter, nutrients, and, in some cases, pollutants from coastal and neritic environments to deep ocean basins (Fernandez-Arcaya et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Puig et al., 2014). By maintaining both vertical and longitudinal connectivity, submarine canyons function as dynamic links between continental, coastal, and deep-marine environments. They regulate sediment redistribution across continental margins and enhance exchanges between shallow and deep systems. Beyond their sedimentary significance, their complex geomorphology influences deep-sea ecological processes by promoting the accumulation of organic matter, thereby sustaining diverse and productive benthic communities.\u003c/p\u003e \u003cp\u003eScientific recognition of submarine canyons began in the early twentieth century, when early bathymetric surveys revealed deeply incised valleys beneath sea level. In 1903, Joseph William Spencer proposed a subaerial fluvial origin linked to low sea-level stands. The pioneering work of Francis Parker (Shepard, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Shepard, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1965\u003c/span\u003e) advanced this field by highlighting both the morphological similarities with continental canyons and the role of distinct marine processes in their formation.\u003c/p\u003e \u003cp\u003eMore recently, advances in multibeam bathymetry and seismic imaging have enabled high-resolution global mapping, revealing thousands of submarine canyons distributed along active and passive margins worldwide (Amblas et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSubmarine canyons are defined as sinuous valleys with steep walls, V-shaped cross sections, and longitudinal profiles sloping seaward (Shepard, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e1965\u003c/span\u003e). Their morphology exhibits considerable variability in form, size, and degree of incision, reflecting the combined influence of tectonic setting, sediment characteristics, and the intensity of hydro-sedimentary processes (Covault et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Farre et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e1983\u003c/span\u003e; Pratson and Coakley, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1996\u003c/span\u003e). Global morphometric analyses reveal clear contrasts between canyons on active margins\u0026mdash;typically narrower and more deeply incised\u0026mdash;and those on passive margins, which are generally broader and less deeply entrenched (Goff, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe origin and long-term evolution of submarine canyons result from the interplay of processes operating across multiple spatial and temporal scales. Turbidity currents are a primary mechanism driving canyon incision and sediment transport to deep basins (Ewing and Heezen, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e1952\u003c/span\u003e; Mulder et al., \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Normark and Carlson, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). These gravity-driven flows may be triggered by submarine landslides, extreme river floods, storms, dense water cascading from the continental shelf, or seismic activity (Nittrouer and Wright, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Puig et al., 2014). Eustatic sea-level changes have also strongly influenced submarine canyon formation, with Quaternary lowstands promoting headward incision and enhancing connections to continental rivers, enabling direct sediment transfer to deep margins (Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Shepard, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1981\u003c/span\u003e). However, canyon evolution reflects the combined action of multiple processes, including retrogressive erosion, gravitational incision, tectonics, fluid seepage, and mass-wasting events (Daly, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e1936\u003c/span\u003e; Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Mountjoy et al., \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2009b\u003c/span\u003e). Therefore, submarine canyons are dynamic systems shaped by both sea-level fluctuations and diverse geomorphic processes.\u003c/p\u003e \u003cp\u003eSubmarine canyons are typically classified based on head configuration and connectivity with river systems into three types : (i) shelf-incising canyons directly connected to rivers, (ii) shelf-incising canyons without direct fluvial connection, and (iii) slope-confined canyons (Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Morphological maturity provides a complementary classification, distinguishing dendritic, sinuous mature canyons from more linear, juvenile forms (Goff, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Twichell and Roberts, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e1982\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLongitudinal profiles\u0026mdash;concave, linear, or convex\u0026mdash;offer insight into dominant processes and tectono-sedimentary context (Covault et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Goff, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Concave profiles are typical of highly erosive active margins, linear profiles of mature passive margins dominated by fluvial input, and convex profiles of tectonically uplifted margins.\u003c/p\u003e \u003cp\u003eBeyond their geomorphological and sedimentary importance, submarine canyons support highly diverse and productive deep-sea ecosystems. Their complex topography enhances organic matter accumulation, bentho-pelagic exchanges, and habitat diversity, thereby sustaining cold-water corals and numerous deep-sea fishes (De Leo et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Fernandez-Arcaya et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e)). In addition, submarine canyons contribute to global carbon cycling through the sequestration and long-term storage of organic carbon.\u003c/p\u003e \u003cp\u003eThe Algerian continental margin in the western Mediterranean is an ideal setting to study submarine canyons due to its complex morphology and tectonic framework, shaped by Africa\u0026ndash;Eurasia convergence, Alpine inheritance, and active sedimentary processes. Bathymetric and seismic data reveal numerous canyons along the slope, particularly between Algiers and Boumerd\u0026egrave;s, characterized by pronounced relief and sinuous courses indicative of active erosion and deposition (Gennesseaux et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Nabila and Sabah, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Canyon morphology varies with shelf width: narrow shelves favor deeply incised canyons, while broader shelves produce more confined forms (Fernane, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Fernane et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Lounes, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Overall, shelf geometry, slope gradient, and structural topography strongly influence canyon formation, though integrated studies along the Algerian margin remain limited.\u003c/p\u003e \u003cp\u003eThis study examines how continental shelf width influences the formation, evolution, and morphometry of submarine canyons along the central Algerian margin using high-resolution bathymetric data, aiming to improve the understanding of submarine incision processes in the western Mediterranean and to refine general models of submarine canyon evolution.\u003c/p\u003e"},{"header":"2. General Framework","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Geographical Overview\u003c/h2\u003e \u003cp\u003eThe central Algerian continental margin constitutes a geostrategically significant segment of the southern Mediterranean coastline. It is characterized by a complex geomorphological setting and pronounced tectonic activity resulting from the ongoing convergence between the African and Eurasian plates. This sector is bounded to the north by the deep Algerian Basin, part of the western Mediterranean Sea, and to the south by the Tellian Atlas, an active fold-and-thrust belt. Geographically, it extends from Tipaza in the west to Boumerdes in the east, encompassing the coastline of the capital city, Algiers, and covering approximately 400 km of shoreline (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn contrast to passive margins, the central Algerian margin is an active compressional margin. It is distinguished by a narrow and steep continental shelf, numerous structural lineaments, and intense crustal deformation associated with plate convergence. The contemporary morphology reflects this tectonic regime, displaying fault-controlled bathymetric features, slope instabilities, and submarine canyon systems shaped by both structural inheritance and morphodynamic processes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Geological Overview\u003c/h2\u003e \u003cp\u003eNorthern Algeria forms part of the Alpine belt known as the Maghrebian Chain. From south to north, this chain is subdivided into three principal structural domains: (1) the external domain, represented by the Tellian units, mainly composed of marls and calcareous sedimentary series; (2) the flysch domain, corresponding to sediments deposited in the Maghrebian Tethys and subsequently involved in subduction processes; and (3) the internal domain, consisting of a Hercynian basement partially overlain by its sedimentary cover, referred to as the Kabylian Dorsale, and interpreted as a remnant of the Alboran\u0026ndash;Kabylian\u0026ndash;Peloritani\u0026ndash;Calabrian (AlKaPeCa) domain. According to (Domzig et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), the subsurface of the study area comprises Oligo-Miocene sedimentary deposits, flysch units, and locally volcanic formations.\u003c/p\u003e \u003cp\u003eThe coastal strip extending from Dellys to Damous crosses the internal zones of the Maghrebian Chain. Lithostratigraphic mapping of the Algiers region reveals a Mio\u0026ndash;Plio\u0026ndash;Quaternary sedimentary cover unconformably overlying a Paleozoic metamorphic basement (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This basement consists predominantly of schists, micaschists, gneisses, and granites, and is strongly tectonized, cropping out notably between the Chenoua and Algiers massifs.\u003c/p\u003e \u003cp\u003eIn the Dellys region, outcrops are largely dominated by olistostromes, flysch deposits, and Tellian marls. These formations are interpreted as evidence of large-scale gravitational sliding within the Oligo-Miocene Kabylian basin. They are unconformably overlain by post-orogenic Miocene deposits, locally intruded by Miocene volcanic products, including the basalts of Cap Djinet (Raymond, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e1976\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe sedimentary cover of the Algerian offshore has been documented in several studies (Auzende, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e1978\u003c/span\u003e; Domzig et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; El-Robrini, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e1986\u003c/span\u003e; Hs\u0026uuml; et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e1973\u003c/span\u003e; Medaouri, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Medaouri et al., \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). A major feature of this cover is the Messinian salt series (Upper Miocene), deposited in basin areas during the Messinian Salinity Crisis (5.96\u0026ndash;5.32 Ma). This event involved a significant sea-level drop and one or more phases of Mediterranean desiccation, leading to intense margin erosion and the accumulation of substantial evaporitic deposits in the basins (Clauzon, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e1982\u003c/span\u003e; Gargani and Rigollet, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Rouchy et al., \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2001\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFollowing the Pliocene reflooding, Pliocene to Quaternary sediments were progressively deposited. The mechanical properties of the Messinian evaporites favor syn-sedimentary mobility and diapiric processes (Domzig et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Climatic and Hydrological Overview\u003c/h2\u003e \u003cp\u003eAlgeria is predominantly characterized by a hot and arid climate, except along its northern coastal fringe, which experiences a Mediterranean-type climate. In coastal cities, winter temperatures typically range between 8\u0026deg;C and 15\u0026deg;C. By late spring, average temperatures reach approximately 25\u0026deg;C, rising to 28\u0026ndash;30\u0026deg;C during July and August.\u003c/p\u003e \u003cp\u003eThe topographic configuration of the coastal relief strongly influences regional climatic conditions, particularly precipitation distribution and intensity. Rainfall exhibits marked spatial and temporal variability, with irregular and occasionally intense events. Data from the National Office of Meteorology (ONM) for the period 1986 to 2025 indicate an average annual precipitation of approximately 690 mm in coastal areas.\u003c/p\u003e \u003cp\u003eThis climate variability plays a crucial role in controlling geological and hydrological processes along northern Algeria\u0026rsquo;s coastal zones. The drainage network within the study area remains relatively underdeveloped. The main watersheds originate in the Tellian Atlas, with the most significant being, from west to east, Oued Mazafran, Oued Isser, and Oued S\u0026eacute;baou (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eToward the western sector of the study area, watershed areas decrease considerably, in some cases to less than 200 km\u0026sup2;, while average slopes increase to 4\u0026ndash;5\u0026deg;. These geomorphological conditions favor the development of short, steep catchments characterized by episodic torrential flows, particularly during autumn and spring. During intense rainfall events, hyperpycnal flows may be generated, potentially playing a key role in sediment transport to adjacent coastal and marine environments.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Data and Methods","content":"\u003cp\u003eThe data set used in this study was acquired during the MARADJA 1 oceanographic survey in September 2003 (MARADJA: MARge Active el DJAzaïr, el Djazaïr = Algiers) on board the Suroît research vessel (IFREMER). Bathymetric and reflectivity data along the slope were obtained using a Kongsberg EM300 Simrad multibeam echosounder, whereas a Kongsberg EM1000 was used to acquire data along the continental platform. The Simrad EM300 is a 32-kHz multibeam system that allows an overall swath coverage of approximately six times the water depth, increasing with depth to a maximum width of 5000 m at 1000 m. Its vertical accuracy can reach 2 m for the central beam and its lateral resolution is at most approximately 25 m. Bathymetric information allows a precise study of seabed morphology, and backscatter data allow the analysis of variations in seabed reflectivity. The depth of multibeam coverage ranges from 60 to 2800 m. The data set allowed the production of a Digital Elevation Model at a spatial resolution of 25 m (\u003cstrong\u003eFig. 2\u003c/strong\u003e).\u003c/p\u003e\n\u003cp\u003eTo delineate the boundaries of submarine canyons and gullies within the study area, a manual digitization approach was employed. This method integrates geomorphometric analysis, GIS-based processing, and morphological classification based on parameters such as size, depth, and degree of incision.\u003c/p\u003e\n\u003cp\u003eThe distinction between submarine canyons and gullies was based on morphometric criteria defined by\u0026nbsp;(Harris and Whiteway, 2011). Two conditions must be simultaneously met for a feature to be classified as a submarine canyon:\u003cbr\u003e\u0026nbsp;(I) The incision of the canyon head relative to the surrounding interfluves must exceed 100 meters;\u003cbr\u003e\u0026nbsp;(II) The depth difference between the canyon head and its foot must be greater than 1000 meters.\u003c/p\u003e\n\u003cp\u003eIf either of these conditions is not satisfied, the feature is classified as a submarine gully.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAdditional morphometric parameters were also considered to further characterize the identified features. These include the width of the continental shelf, the total length of canyons and gullies, as well as the depth at the canyon head. These indicators provide valuable insights into the geometry, spatial organization, and degree of development of the submarine incision systems within the study area.\u003c/p\u003e"},{"header":"4. Results","content":"\u003cp\u003eThe morphological analysis of the central Algerian margin highlights a clear lateral segmentation of the shelf\u0026ndash;slope system (\u003cstrong\u003eFig. 3\u003c/strong\u003e). Three morpho-structural sectors were distinguished:\u003cbr\u003e\u0026nbsp;(i) an eastern sector between Cap Matifou and Tigzirt;\u003cbr\u003e\u0026nbsp;(ii) a central sector encompassing the Bay of Bou Isma\u0026iuml;l and the Bay of Algiers;\u003cbr\u003e\u0026nbsp;(iii) a western sector extending between Cap Chenoua and Cap T\u0026eacute;n\u0026egrave;s.\u003c/p\u003e\n\u003cp\u003eThis spatial organization reveals a direct relationship between the width of the continental shelf, the morphology of the adjacent coastline, and the degree of development and formation of submarine canyons.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003ch3\u003eEastern sector: characterized by a narrow shelf with strong slope incision:\u003c/h3\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe eastern sector is characterized by a narrow continental shelf (\u0026lt; 20 km), directly bordered by elevated coastal massifs (Thenia and Dellys massifs). The shelf\u0026ndash;slope transition is abrupt, with slopes locally exceeding 10\u0026ndash;15%.\u003c/p\u003e\n\u003cp\u003eThe slope is deeply incised by a dense network of submarine canyons sensu stricto, organized into hierarchical systems with multiple tributaries. These canyons include, from east to west, the Dellys Canyon, the Sebaou Canyon, and the Algiers Canyon. Canyon heads are located in close proximity to the shelf break, and several systems extend to the deep basin, indicating efficient sediment transport.\u003c/p\u003e\n\u003cp\u003eThe high density of incisions, their depth, and their longitudinal continuity suggest (i) sustained sediment supply from short and steep catchments and (ii) concentration of sediment fluxes at the shelf edge.\u003c/p\u003e\n\u003cp\u003eThe geometric configuration of the shelf therefore promotes sediment bypass and long-term slope incision.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003ch3\u003eCentral sector: wide shelf with limited incision:\u003c/h3\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eIn contrast, the central sector displays a markedly wider continental shelf (\u0026gt; 30\u0026ndash;40 km), developed offshore from low-relief coastal plains (Mitidja Plain).\u003c/p\u003e\n\u003cp\u003eSubmarine incision is weakly developed. The observed forms correspond predominantly to shallow, rectilinear gullies lacking hierarchical organization and confined to the upper slope or shelf edge. Their spatial distribution is discontinuous, and their longitudinal extent remains limited. The absence of mature canyons suggests lateral dispersion of sediment supply across the widened shelf, thereby reducing flow focusing at the slope.\u003c/p\u003e\n\u003cp\u003eThus, the wide shelf acts as a zone of sediment accommodation and dissipation, limiting the development of deep incisions.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\n \u003ch3\u003eWestern sector: very narrow shelf with strong incision:\u003c/h3\u003e\n \u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eIn the western sector, the continental shelf narrows again (5\u0026ndash;10 km) and is bordered by steep coastal massifs (T\u0026eacute;n\u0026egrave;s Massif). The slope exhibits steep gradients approaching 20 % and high morphological roughness.\u003c/p\u003e\n\u003cp\u003eNumerous submarine canyons are developed in this sector, including the Gouraya Canyon and the Chlef Canyon. They display predominantly linear to sub-linear courses, steep interfluves, and locally stepped longitudinal profiles.\u003c/p\u003e\n\u003cp\u003eThe very strong incision observed in this sector reflects:\u003cbr\u003e\u0026nbsp;(i) concentration of gravity-driven flows; (ii) structural and lithological control; (iii) enhanced efficiency of continent\u0026ndash;basin coupling.\u003c/p\u003e\n\u003ch2\u003eRegional Controls on Canyon Distribution\u003c/h2\u003e\n\u003cp\u003eComparison of the three sectors highlights a first-order morphological control exerted by continental shelf width and coastal physiography.\u003c/p\u003e\n\u003cp\u003eTwo principal configurations emerge:\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003eNarrow shelf + coastal massifs (eastern and western sectors) \u0026rarr; high canyon density, deep incision, concentrated sediment transfer.\u003c/li\u003e\n \u003cli\u003eWide shelf + coastal plains (central sector) \u0026rarr; limited incision, predominance of gullies, dispersed sediment fluxes.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThese results indicate that shelf width modulates sediment flux focusing at the continental margin, conditioning the transition from a morphology dominated by gullies to one dominated by well-developed submarine canyons.\u003c/p\u003e\n\u003cp\u003eAt the regional scale, the central Algerian margin thus appears segmented according to a morphodynamic gradient controlled by margin geometry, adjacent continental relief, and structural inheritance.\u003c/p\u003e"},{"header":"5. Discussion","content":"\u003cp\u003eThe results obtained along the central Algerian margin clearly highlight a first-order morphological control exerted by continental shelf width on the genesis, organization, and degree of maturity of submarine incision systems. Although this relationship has been suggested in several global studies, it appears particularly structuring at the regional scale, where lateral segmentation of the margin corresponds to marked contrasts between domains dominated by deeply incised canyons and sectors characterized by weakly developed gullies.\u003c/p\u003e \u003cp\u003eThe eastern and western sectors, characterized by narrow shelves (5\u0026ndash;20 km), exhibit a high density of deeply incised canyons with predominantly concave to sublinear longitudinal profiles. This configuration is consistent with observations from the Gulf of B\u0026eacute;ja\u0026iuml;a and the western Algerian margin (Dahra margin), where incision is also associated with reduced shelf width and steep slopes (Fernane, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; Fernane et al., \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Lounes, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Nabila and Sabah, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn contrast, the central sector (Bay of Algiers \u0026ndash; Bay of Bou Isma\u0026iuml;l), marked by a wider shelf (\u0026gt;\u0026thinsp;30\u0026ndash;40 km), displays limited incision dominated by weakly hierarchical gullies. This organization is consistent with models proposed for relatively more stable portions of the western Algerian margin, where lateral dissipation of sediment flux reduces the focusing of gravity-driven flows (A\u0026iuml;di et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Domzig et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2006\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAt the scale of the Algerian margin, our results confirm that shelf width acts as a morphodynamic filter controlling the transition from a regime of concentrated sediment bypass (narrow shelf) to a regime of accommodation and storage (wide shelf). This dynamic occurs within an active compressive tectonic context related to Africa\u0026ndash;Eurasia convergence, which enhances slope gradients and promotes gravitational instability (Bouyahiaoui et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2015\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAt the scale of the western Mediterranean, comparable results have been described along the Catalan margin and the Gulf of Lion, where deeply incised canyons are associated with relatively narrow shelves and active fluvial systems (Amblas et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Puig et al., 2014). Similarly, on the Sardinian margin recently studied by (Caradonna et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), canyon morphology shows a strong correlation between shelf geometry and incision style. Sectors with narrow shelves display canyons efficiently connected to the deep basin, whereas wider shelves favor the development of shallow gully networks.\u003c/p\u003e \u003cp\u003eThe central Algerian margin therefore fits well within the Mediterranean model of active margins characterized by strong morphological segmentation, where lateral variability in shelf width modulates the intensity of continent\u0026ndash;basin coupling.\u003c/p\u003e \u003cp\u003eAt the global scale, (Harris and Whiteway, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) demonstrated that canyons along active margins are generally shorter, narrower, and more deeply incised than those developed along passive margins. The characteristics observed in the eastern and western sectors of the Algerian margin are consistent with this model, with steep slopes and pronounced incision. Comparable observations have been reported offshore California and Chile, where narrow continental shelves associated with compressive margins favor the development of canyons deeply connected to abyssal basins (Covault et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; Mountjoy et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2009a\u003c/span\u003e). In contrast, along passive margins such as the northwestern Atlantic margin, wide shelves and gentler slopes favor broader canyons with less abrupt profiles, often dominated by sediment reworking processes rather than intense gravitational incision (Pratson and Coakley, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e1996\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOur results therefore confirm that shelf width constitutes a key morphometric parameter, although its effect is amplified or modulated by tectonic setting, slope gradient, lithological nature, and sediment supply.\u003c/p\u003e \u003cp\u003eThe differences observed among the three sectors of the central Algerian margin suggest two contrasting morphodynamic regimes:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eConcentrated transfer regime (narrow shelf)\u003c/b\u003e: high gravitational energy, sustained incision, efficient connection to the deep basin, and increased potential for turbidity currents and submarine landslides.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eLateral dissipation regime (wide shelf)\u003c/b\u003e: temporary sediment storage, dispersion of sediment flux, and incision largely restricted to the upper slope.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThese findings are consistent with sediment transfer models proposed by (Fildani, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2017\u003c/span\u003e), according to which margin geometry controls source-to-sink connectivity and the frequency of gravity-driven events. From a geological hazard perspective, sectors characterized by narrow shelves may present increased susceptibility to gravitational instabilities and submarine-generated tsunamis, consistent with regional analyses conducted after the Boumerd\u0026egrave;s earthquake (A\u0026iuml;di et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eContinental shelf width is a key factor controlling the development, organization, and maturity of submarine incision systems along the central Algerian margin. Narrow shelves (5\u0026ndash;20 km) are associated with deeply incised, hierarchically organized canyons and concentrated sediment transfer, while wide shelves (\u0026gt;\u0026thinsp;30 km) favor shallow gullies, lateral sediment dispersion, and limited slope incision.\u003c/p\u003e \u003cp\u003eShelf width interacts with slope gradient, tectonic compression, structural inheritance, and sediment supply to determine whether submarine systems evolve into mature, basin-connected canyons or remain confined as gullies.\u003c/p\u003e \u003cp\u003eThese insights have both scientific and applied significance: narrow-shelf sectors are prone to slope instability, submarine landslides, and tsunami hazards. Integrating morphometric parameters into sediment transfer and hazard models is therefore essential.\u003c/p\u003e \u003cp\u003eOverall, this study highlights the fundamental role of margin geometry in shaping canyon\u0026ndash;gully systems and provides a framework for future research combining bathymetry, seismic data, and numerical modeling to better understand source-to-sink dynamics and predict the evolution of active continental margins.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAuthor Contributions All authors contributed significantly to the development of this work.[Author 1: Nadia Amarni]: Conceptualization, Data Collection, Formal Analysis, Writing \u0026ndash; Original Draft.[Author 2: Lounes Fernane]: Supervision, Methodology.[Author 3: Ryhane Lounas]: Review and Editing, Validation.All authors have read and approved the final version of the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eA\u0026iuml;di, C., Beslier, M.-O., Yelles-Chaouche, A.K., Klingelhoefer, F., Bracene, R., Galve, A., Bounif, A., Schenini, L., Hamai, L. and Schnurle, P.J.T., 2018. 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Paleoenvironmental changes at the Messinian\u0026ndash;Pliocene boundary in the eastern Mediterranean (southern Cyprus basins): significance of the Messinian Lago-Mare. 145(1-2): 93-117.\u003c/li\u003e\n \u003cli\u003eShepard, F.P.J.A.b., 1981. Submarine canyons: multiple causes and long-time persistence. 65(6): 1062-1077.\u003c/li\u003e\n \u003cli\u003eShepard, F.P.J.P.i.o., 1965. Importance of submarine valleys in funneling sediments to the deep sea. 3: 321-332.\u003c/li\u003e\n \u003cli\u003eTwichell, D.C. and Roberts, D.G.J.G., 1982. Morphology, distribution, and development of submarine canyons on the United States Atlantic continental slope between Hudson arid Baltimore Canyons. 10(8): 408-412.\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":"Central Algerian margin, Continental shelf, Submarine canyons, Submarine gullies, Sediment dynamics.","lastPublishedDoi":"10.21203/rs.3.rs-9129667/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9129667/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eErosive dynamics in deep marine environments are strongly controlled by the morphology of the continental shelf, particularly along active margins. On the central Algerian margin, where shelf width varies laterally, submarine incision manifests through the co-development of deeply incised canyons and dense gully networks. This study investigates how shelf width influences the formation, spatial distribution, and evolution of these erosive features, based on high-resolution bathymetric data acquired during the MARADJA 1 cruise (2003) and through detailed morphometric analyses.\u003c/p\u003e \u003cp\u003eThe results reveal that in areas where the continental shelf is narrow (5_20 km), gravitational processes are highly focused, promoting the development of deeply incised canyons characterized by steep slopes, smooth longitudinal profiles, and hierarchical drainage networks. Conversely, wider shelf areas (30_40 km) facil\u0026iacute;tate a gradual dissipation of sedimentary energy, leading to the formation of dense but shallow gully networks, organized in a less hierarchical pattern. The spatial distribution of these erosive forms suggests that shelf width acts as a morphological filter, controlling sediment transfer pathways to the slope and deep basin.\u003c/p\u003e \u003cp\u003eThese findings provide new insights into the geomorphological processes shaping the evolution of continental margins and highlight the critical role of morphological parameters in modeling sediment transfer and assessing associated geological hazards, such as submarine landslides and tsunamis.\u003c/p\u003e","manuscriptTitle":"Control of shelf width on submarine canyon formation along the central Algerian margin","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-26 06:42:23","doi":"10.21203/rs.3.rs-9129667/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":"5615510e-a175-478c-8d45-cad9afbac199","owner":[],"postedDate":"March 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-03-26T06:42:24+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-26 06:42:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9129667","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9129667","identity":"rs-9129667","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}