Depositional Record最新文献

{"title":"Exploring the application of dual-energy CT to discriminate sediment facies in a varved sequence","authors":"M. Martini,&nbsp;P. Francus,&nbsp;L. Di Schiavi Trotta,&nbsp;P. Letellier,&nbsp;M. Des Roches,&nbsp;P. Després","doi":"10.1002/dep2.271","DOIUrl":"10.1002/dep2.271","url":null,"abstract":"<p>Dual-energy X-ray computed tomography consists of imaging objects using two incident X-ray beams of different energy to distinguish the different compounds within a sample based on their density (electron density, <i>ρ</i>_<i>e</i>) and elemental composition (effective atomic number, <i>Z</i>_<i>eff</i>). The stoichiometric calibration for dual-energy X-ray computed tomography was already successfully implemented to identify single and homogeneous minerals easily and non-destructively. It is here applied for the first time to a more complex and heterogeneous sample, a varved sediment core with three distinct facies. The output of dual-energy X-ray computed tomography was compared against elemental geochemistry obtained at the same resolution using a micro-XRF core scanner. The three individual facies can be successfully differentiated using dual-energy X-ray computed tomography because their range of <i>ρ</i>_<i>e</i> and <i>Z</i>_<i>eff</i> values allow their discrimination. Correlations with elemental geochemistry are also discussed but are less conclusive, probably because of variations in grain size and porosity, and because these high resolution analyses were not performed at the exact same location. The paper not only eventually discusses the limitations when using dual-energy X-ray computed tomography on sediments but also demonstrates its potential to quantitatively study sediment cores in a non-destructive way.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.271","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139685590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic biology influences sedimentation in submarine channel bends: Coupling of biology, sedimentation and flow","authors":"M. Azpiroz-Zabala,&nbsp;E. J. Sumner,&nbsp;M. J. B. Cartigny,&nbsp;J. Peakall,&nbsp;M. A. Clare,&nbsp;S. E. Darby,&nbsp;D. R. Parsons,&nbsp;R. M. Dorrell,&nbsp;E. Özsoy,&nbsp;D. Tezcan,&nbsp;R. B. Wynn,&nbsp;J. Johnson","doi":"10.1002/dep2.265","DOIUrl":"https://doi.org/10.1002/dep2.265","url":null,"abstract":"<p>Submarine channels are key features for the transport of flow and nutrients into deep water. Previous studies of their morphology and channel evolution have treated these systems as abiotic, and therefore assume that physical processes are solely responsible for morphological development. Here, a unique dataset is utilised that includes spatial measurements around a channel bend that hosts active sediment gravity flows. The data include flow velocity and density, alongside bed grain size and channel-floor benthic macrofauna. Analysis of these parameters demonstrate that while physical processes control the broadest scale variations in sedimentation around and across the channel, benthic biology plays a critical role in stabilising sediment and trapping fines. This leads to much broader mixed grain sizes than would be expected from purely abiotic sedimentation, and the maintenance of sediment beds in positions where all the sediment should be actively migrating. Given that previous work has also shown that submarine channels can be biological hotspots, then the present study suggests that benthic biology probably plays a key role in channel morphology and evolution, and that these need to be considered both in the modern and when considering examples preserved in the rock record.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.265","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139976567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The provenance of a turbidite system within a tectonically active wrench basin: Insights from heavy mineral characteristics of Miocene sandstones in the Tabernas Basin, south-east Spain","authors":"Paula McGill,&nbsp;Alex W. Milne,&nbsp;Andrew Morton,&nbsp;Gwyd Williams","doi":"10.1002/dep2.270","DOIUrl":"10.1002/dep2.270","url":null,"abstract":"<p>This paper provides insight into the provenance of the Late Miocene turbidite succession of the Tabernas Basin. Although this area has been extensively studied, only limited attention has been paid to sediment provenance. Through heavy mineral analysis, it has been possible to identify provenance-related signatures from the adjacent Sierra de los Filabres and Sierra Alhamilla uplifts. Stable mineral ratio data confirm that the Sierra de los Filabres provided sediment with generally higher chloritoid:tourmaline and higher Type Bii garnet abundances than those derived from the Sierra Alhamilla. By comparison, modern sediments derived from the Sierra Alhamilla have garnet compositions with larger proportions of Types A and C, suggesting that the basinal sediments were not sourced from the incipient Sierra Alhamilla Uplift. Heavy mineral analysis confirms that the Sierra de los Filabres was the primary source for the Tabernas succession, with minor variations indicating that the erosive part of the system migrated across the uplift. Input was predominantly from the Nevado–Filábride Complex, with minor amounts from the small remnant of the Alpujarride Complex attached to the southern margin of the Sierra de los Filabres. Evidence strongly suggests a single sediment routing system but identifies some subtle provenance variations. In particular, there was a shift in detrital garnet composition between the Sartenella Formation and the Verdelecho Formation, Solitary Channel and El Gordo Megabed, which is attributed here to a shift in catchment within the Sierra de los Filabres. This shift appears to have occurred during the deposition of the Sartenella Formation, since the garnet compositions of the Verdelecho Formation and Solitary Channel are similar to each other and differ from the preceding part of the Sartenella Formation. The Solitary Channel displays marked heterogeneities in provenance character, manifested by changes in chloritoid abundance, consistent with previous studies that suggest the depositional architecture in the channel was influenced by high-frequency changes in sediment flux and sea level.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.270","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139598139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Facies distribution and depositional cycles in lacustrine and palustrine carbonates: The Lutetian–Aquitanian record in the Paris Basin","authors":"Kévin Moreau,&nbsp;Simon Andrieu,&nbsp;Justine Briais,&nbsp;Benjamin Brigaud,&nbsp;Magali Ader","doi":"10.1002/dep2.264","DOIUrl":"10.1002/dep2.264","url":null,"abstract":"<p>The difficulty of correlating continental deposits hinders predicting lacustrine and palustrine carbonate facies variations in time and space. This study aims to understand better the factors governing these facies heterogeneities by measuring carbonate isotopes and conducting facies, petrographic and sequence stratigraphic analyses of the Lutetian–Aquitanian deposits of the Paris Basin, that record the transition from marine to lacustrine environments. Large-scale correlations enabled the definition of two lacustrine–palustrine carbonate facies models. (1) The coastal lacustrine system (Bartonian to Rupelian), consists of fine-grained brackish carbonate exhibiting episodic marine inputs during short-term relative sea-level maxima and evaporite sedimentation during relative sea-level minima. Lacustrine sediments differ notably from marine ones with more negative δ¹³C and δ¹⁸O compositions that co-vary and a biota adapted to low salinity conditions. In the associated palustrine environment, depositional sequences evolve upwards from micritic lacustrine deposits to nodular and then laminar calcretes. Microbial-coated grains and rhizoliths indicate biological processes during repeated subaerial exposure phases in sub-tropical to arid climates. (2) The inland lacustrine system (Rupelian and Aquitanian) was disconnected from the marine domain and showed evidence of microbial activity with microbial crusts and oncoidal rudstones. Facies rich in micritic intraclasts composed of palustrine and lacustrine facies indicate the reworking of already lithified sediments along the margins. In the palustrine domain, the calcrete facies are less abundant than breccias formed <i>in-situ</i> by desiccation, limestones with root traces, or organic-rich wackestones and marls. This system reflects a more temperate climate with more developed microbial structures and less exposed carbonates than the coastal lacustrine system. The southward migration of the depocentre and the transition from marine environments to (1) coastal and then (2) inland systems are controlled by uplift phases induced by Pyrenean and Alpine orogenesis. Third-order relative sea-level variations appear to control only short-term cycles in coastal systems.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.264","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139176285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Biogenicity of amorphous organic matter and bacteriomorph acritarchs preserved in wrinkle structures from the Ediacaran Cíjara Formation, Spain","authors":"J. Javier Álvaro,&nbsp;José E. Ortiz,&nbsp;Carlos Neto de Carvalho,&nbsp;Ignacio López-Cilla,&nbsp;Yolanda Sánchez-Palencia,&nbsp;Trinidad Torres","doi":"10.1002/dep2.258","DOIUrl":"10.1002/dep2.258","url":null,"abstract":"<p>Establishing the biogenicity of sedimentary surface textures with unresolved microbial origin is critical to any environmental and geobiological interpretation of clastic settings. Here, some Ediacaran wrinkle structures and associated carbonaceous greywacke samples containing mat fragments rich in ‘bacteriomorph acritarchs’ are investigated. Their biogenicity was evaluated with transmitted light and scanning electron microscopy, epifluorescence and Raman spectroscopy, and confirmed by the presence of distinct cyanobacterial biomarkers. The comparison of results yielded by these techniques validates the use of Raman spectroscopy on Neoproterozoic kerogen (organic-walled microfossils and amorphous organic material) under low metamorphic conditions. Raman spectrographs also allowed recognition of associated rare-earth element-rich phosphate (monazite) and subsidiary metal sulphide concentrations, and interpreted as a result of biosorption and/or mat trapping under normal oxic conditions. These microbial mat features represent cyanobacterial bloom-forming <i>Bavlinella</i> acritarchs, which characterise eutrophic episodes in a semi-enclosed retroarc basin sandwiched between an active Cadomian arc and West Gondwana.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.258","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139183546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sequence stratigraphical and palaeoenvironmental implications of Cenomanian–Santonian dinocyst assemblages from the Trans-Sahara epicontinental seaway: a multivariate statistical approach","authors":"Musa B. Usman,&nbsp;David W. Jolley,&nbsp;Alexander T. Brasier,&nbsp;Adrian J. Boyce","doi":"10.1002/dep2.260","DOIUrl":"10.1002/dep2.260","url":null,"abstract":"<p>The Cretaceous was punctuated by episodic flooding of continental margins forming epicontinental seas. The Trans-Sahara Seaway was one of these epicontinental seas, connecting the Gulf of Guinea with the Tethys Ocean. In this study, data including microplankton abundances, stable carbon isotopes of organic material and elemental geochemistry were integrated with traditional sedimentological analyses from the Trans-Sahara Seaway. The carbon isotopic data provide the first evidence that oceanic anoxic event 2 was present in the Trans-Sahara Seaway, and palynology shows it was associated with an increase in peridinioid dinocyst abundance. A combined study of microplankton assemblages and sedimentology reveals palaeoenvironmental trends linked to sea-level change. Lowstand system tracts were characterised by increased siliciclastic grain size, low microplankton diversity, and were dominated by Chlorophyceae. Transgressive system tracts were associated with diversity increases during rising sea level, with open marine gonyaulacoid dinocysts dominating the assemblages. Maximum flooding surfaces were recognised by the highest increase in biological diversity in argillaceous deposits. As sea level started to fall, the peridinioid dinocysts became dominant, with decreased microplankton diversity during highstand systems tracts. This combination of sedimentology and interpretation of dinocyst assemblages allows the identification of shallow to deeper marine depositional sequences of Cenomanian–Santonian strata within the Yola Sub-basin. This approach could be used to delineate marine depositional sequences where using conventional sedimentological methods alone is very challenging.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.260","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139183549","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterising the heterogeneous nature of tufa mounds by integrating petrographic, petrophysical, acoustic and electromagnetic measurements","authors":"S. Schröder,&nbsp;J. P. Corella,&nbsp;X. M. Pellicer,&nbsp;P. Rook,&nbsp;A. Kara,&nbsp;X. Comas","doi":"10.1002/dep2.259","DOIUrl":"10.1002/dep2.259","url":null,"abstract":"<p>Determination of the physical properties of subsurface geological bodies is essential for georesource management and geotechnical applications. In the absence of direct measurements, this usually passes via geophysical methods such as seismic and ground-penetrating radar. These require conversion to physical properties, and measurements at different scales to test for consistency. This approach is non-trivial in geobodies with heterogeneous patterns of properties. Tufa mounds—in-situ terrestrial carbonate buildups precipitating from geothermal waters—are characterised by high contrasts in facies and petrophysical properties from microscale to macroscale, and are therefore ideally suited to test the ability of non-invasive geophysical methods to estimate such contrasts, and to develop petrophysical models based on geophysical properties. Here, a laboratory-based study of a Pleistocene tufa mound in Spain is presented that combines (1) petrography, (2) digital 2D pore network analysis, (3) gas porosity and permeability measurements, (4) acoustic velocity measurements and (5) electromagnetic wave velocity and porosity determination from ground-penetrating radar, to develop empirical petrophysical models. These results show the consistency of petrophysical properties determined with different methods across various observational scales. Electromagnetically derived porosity positively correlates with gas porosity. Petrophysical properties depend on measurable rock fabric parameters and the degree of cementation, which provide predictive tools for subsurface geobodies. Strongly cemented peloidal-thrombolitic fabrics with intergranular and intercrystalline pores, and a dominance of small complex pores best transmit acoustic waves. Weak cementation and a significant fraction of large simple pores (framework, vegetation moulds) increase porosity and permeability of shrubby fabrics, while causing lower acoustic velocity. This study demonstrates that ground-penetrating radar models can be used in combination with direct measurements of physical subsurface properties to capture highly contrasting physical properties associated with different sedimentary facies that would not be achievable with other methods, thus improving the understanding of formational processes.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.259","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139254383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Testing geological proxies for deep‐time tidal model simulations","authors":"B. Guo, L. A. M. Fitzgerald, J. M. Hewitt, O. Pampaloni, J. A. M. Green","doi":"10.1002/dep2.256","DOIUrl":"https://doi.org/10.1002/dep2.256","url":null,"abstract":"Abstract Tides are a key driver of a range of Earth system processes, and we now have the capacity to simulate tidal dynamics on a range of temporal and spatial scales. Deep‐time tidal model simulations have been used to provide insight into past ocean circulation patterns, evolution of life and the developments of the Earth‐Moon system's orbital configuration. However, these tidal model simulations are relatively poorly constrained and validated because of a lack of readily available proxies. The feasibility of using two types of proxy is explored here; (1) sedimentary deposits which can directly estimate palaeotidal ranges, and (2) black shale, to constrain three palaeotidal model simulations for different time slices. Specifically, three palaeotidal range proxies were used for the early Devonian (400 Ma), three palaeotidal range proxies and five black shales for the lower Jurassic (185 Ma), and eight black shales for the early Cretaceous (95 Ma). Both tidal proxies confirm the tidal model results in most locations. The model results for 400 Ma and 185 Ma matched 2/3 of the palaeotidal range proxies for each of these periods. The locations of black shale were compared with tidal front locations predicted by the model outputs based on the Simpson–Hunter parameter and the model results from 95 to 185 Ma agree with the black shale proxies in 10/13 of the locations. In the cases where there is a disagreement, the model resolution is probably too low to fully resolve the details of the coastal topography, or—in one case—the palaeobathymetry is incorrect. Consequently, it is argued that it is worth expanding this type of work, and that such data can be used to validate both models and reconstructions.","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135889007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The origin of planar lamination in fine‐grained sediment deposited by subaqueous sediment gravity flows","authors":"Omar N. Al‐Mufti, R. William C. Arnott","doi":"10.1002/dep2.257","DOIUrl":"https://doi.org/10.1002/dep2.257","url":null,"abstract":"Abstract Planar lamination is a ubiquitous component of modern and ancient fine‐grained sediments deposited by subaqueous sediment gravity flows. These sediments commonly exhibit alternating sub‐millimetre‐thick, sharply bounded silt‐rich and clay‐rich layers that change little in thickness or sediment texture over lateral distances that range up to at least several tens of metres. Silt‐rich layers are moderately to well‐sorted and a few tens to hundreds of microns to a single silt‐grain thick. In contrast, clay‐rich layers are more poorly sorted, and a few tens to hundreds of microns thick. The thickness and regular alternation of these texturally differentiated interlayers, in addition to the absence of features suggesting transport bypass or deposition by migrating rugged bed forms, suggest alternating physical processes and related modes of deposition in the near‐bed region immediately above the bed. Previous interpretations have focussed on clay flocculation, which is difficult to reconcile with the high fluid shear conditions in the near‐bed region. Here it is suggested that in the millimetre to sub‐millimetre‐thick viscous sublayer at the base of a hydraulically smooth turbulent flow, a combination of high fluid shear and sediment concentration initially leads to shear thinning and enhanced mobility in the lower part of the flow, and for silt to continue settling to the bed forming a well‐sorted silt lamina. As silt settles and clay‐size sediment increases in concentration, hydrodynamic lubrication forces strengthen and reduce mobility of the near‐bed part of the flow. This condition is then perturbed by a bedward‐directed outer flow disturbance that dramatically increases frictional stresses and effective fluid viscosity and ultimately shear jamming that causes gelling and deposition of a poorly sorted clay‐rich layer. This process is then repeated multiple times to build up a deposit composed of alternating silt‐rich and clay‐rich laminae overlain by structureless mud deposited directly from suspension.","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135758764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An integrated petrographical and geochemical study of the Tredian Formation in the Salt and Trans-Indus Surghar ranges, North-West Pakistan: Implications for palaeoclimate","authors":"Kamil Ahmed Qureshi,&nbsp;Muhammad Rizwan,&nbsp;Hammad Tariq Janjuhah,&nbsp;Ihtisham Islam,&nbsp;George Kontakiotis,&nbsp;Ahmer Bilal,&nbsp;Mohamad Arif","doi":"10.1002/dep2.255","DOIUrl":"10.1002/dep2.255","url":null,"abstract":"<p>The Middle Triassic Tredian Formation is well exposed in the western region of the Salt Range. It is mostly composed of sandstone with minor alternations of shales and dolomite. This is the first integrated attempt using petrographical and geochemical features to reveal palaeoclimate during deposition of the Tredian Formation. This work sheds light on the petrographical and geochemical properties of the Tredian sandstone in order to date various layers and evaluate the palaeoclimate. The formation was sampled at two distinct stratigraphic layers for petrographic and geochemical analysis of major and trace elements. The sandstone of the Tredian Formation is sub-feldspathic to feldspathic arenite with sub-angular to rounded grains that are moderately to extensively sorted. The relative proportions of the quartz, feldspars and lithoclasts in the examined sandstone samples shows that the Tredian sediments originated from the interior of the craton during a transitional continental regime. Chemical index of alteration values of 59, chemical index of weathering values of 67, and plagioclase index of alteration values of 74.5 indicate a low to moderate degree of weathering in the Tredian sediment source region. Based on the silica content, SiO₂/Al₂O₃ ratios (2.7–6.1; mean 4.1), and chemical maturity index, it is deduced that the Tredian Formation was deposited in chemically immature to sub-mature and dry to semi-arid conditions. Geochemical proxies indicate the acidic source of sediment and deposition on the passive margin of the Indian Plate. The trace element characteristics of the sediments, especially the Rb/Sr, Cu/Zn, Ni/Co, V/Cr and Sr/Ba ratios, indicate that the sediments originated from the first weathering cycle and support the notion that they were deposited in an oxidising continental environment. A semi-arid to arid palaeoclimate predominated through the Middle Triassic at the north-western passive continental margin of the Indian Plate in the south-eastern Neo-Tethys.</p>","PeriodicalId":54144,"journal":{"name":"Depositional Record","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2023-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dep2.255","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135758628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}