Sedimentary Geology最新文献

{"title":"Linking dolomitization to sequence stratigraphy: Insights from the Upper Jurassic Arab Formation, offshore oilfield, UAE","authors":"Xiaolan Jia ,&nbsp;Mohammad Alsuwaidi ,&nbsp;Daniel Morad ,&nbsp;Juan Diego Martín-Martín ,&nbsp;Xia Wang ,&nbsp;Kate Al Tameemi ,&nbsp;Bashayer Al Muhairi","doi":"10.1016/j.sedgeo.2024.106772","DOIUrl":"10.1016/j.sedgeo.2024.106772","url":null,"abstract":"<div><div>This petrographic, petrophysical, and geochemical study revealed that dolomitization in the Upper Jurassic Arab Formation reservoir, United Arab Emirates, can be constrained within 2nd, 3rd, and 4th order sequences. The formation represents a 2nd order regressive sequence/cycle (highstand systems tracts, HST) that was deposited across a carbonate ramp with shoal under hot arid climatic conditions during the Kimmeridgian-Tithonian. Deposition occurred subsequent to maximum marine transgression (maximum flooding surface, MFS) and was accompanied by a progressive increase in the degree of restriction of the connectivity between the inner platform (supratidal, upper intertidal and lagoon) and the open sea. Sporadic dolomitization took place in transgressive systems tracts (TST) of the 3rd and 4th order cycles of earliest stages of the 2nd order regression, below the parasequence boundaries and within bioturbation sites. Subsequent rapid and extended 2nd order marine regression cycles were embossed by trends of progressive increase in salinity, which resulted in concomitant systematic decrease in limestone deposition and increase in intensity of seepage reflux/sabkha dolomitization by seepage reflux of hypersaline brines. Dolomitization is most prevalent in the 4th order HST sequences and was accompanied by occlusion of the moldic and intercrystalline pores in the dolostones by gypsum/anhydrite cement. Dolomitization that was accompanied by limited formation of gypsum/anhydrite in the late 2nd order HST is attributed to reflux of penesaline (salinity saturated with Ca-sulfate) /mesohaline (below Ca-sulfate saturation) brines. The reflux of the latter brines is attributed to smaller extent of relative sea-level falls, i.e., partial restriction of the inner platform. The precipitation of dolomite cement in moldic pores and as thin overgrowths around replacive dolomite is attributed to the flow hot basinal brines (i.e., hydrothermal fluids). This interpretation is supported by the presence of saddle dolomite, along with depleted δ¹⁸O values, relative enrichment in ⁸⁷Sr isotope, and high fluid-inclusions homogenization temperatures. The greater amounts of these post-dolomitization cements in the dolopackstones and dolograinstones caused stronger obliteration of their near-surface isotopic signatures compared to the dolomudstones and dolowackestones.</div><div>This study demonstrates that linking dolomitization of limestones across carbonate ramps under hot-arid climatic conditions to different orders of changes in the relative sea level and lithology of the succession indicates the involvement of various types of dolomitizing fluids and geochemical conditions, including: (i) domination of seepage reflux of hypersaline and mesohaline/penesaline brines, (ii) dolomitization below the seafloor during marine transgression, and (iii) dolomitization within bioturbation sites.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"474 ","pages":"Article 106772"},"PeriodicalIF":2.7,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705946","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of lake level fluctuations in the Early Cretaceous Songliao Basin supports aquifer eustacy","authors":"Zilong Wang,&nbsp;Shaobin Guo","doi":"10.1016/j.sedgeo.2024.106770","DOIUrl":"10.1016/j.sedgeo.2024.106770","url":null,"abstract":"<div><div>Clear geochronology and precise interpretation of sequence stratigraphy enhance our understanding of continental lake-level evolution. The Songliao Basin features well-preserved Cretaceous continental strata. Nevertheless, the correlation between lake-level fluctuations and global sea-level changes remains ambiguous. High-resolution gamma ray logging data were used to analyze the cyclical stratigraphy of the lower member of the Early Cretaceous Shahezi Formation in the Songliao Basin. X-ray fluorescence experiments characterized the sedimentary environment of this formation. Lake-level variations in the lower part of the Early Cretaceous Shahezi Formation were reconstructed using sedimentary noise modeling based on finely tuned gamma ray logging data. Time series analysis using the tuned gamma ray data established an astronomical timescale of approximately 2.4 Myr within the lower section of the early Cretaceous Shahezi Formation in the Songliao Basin. A volcanic ash layer dating (118.20 ± 1.5) Ma from the base of the Shahezi Formation served as an anchor point, providing an absolute astronomical timescale ranging from 115.80 to 118.20 Ma for the study region. The sedimentary model indicates that variations in paleowater depth within the lower section of the Shahezi Formation closely match fluctuations observed in the Fe/Mn index, which reflects paleowater depth changes. This introduces a novel approach to assess changes in continental lake levels. The sedimentary noise model revealed a notable obliquity cycle of about 1.2 million years, strongly associated with fluctuations in lake levels. This indicates that prolonged obliquity periods affect lake level variations. Intriguingly, when lake levels rise, global sea levels concurrently decline, highlighting an inverse relationship between these phenomena. This observation offers insights into how long-term obliquity-driven climate changes regulate sea and lake levels.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"474 ","pages":"Article 106770"},"PeriodicalIF":2.7,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142655372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tufas record significant imprints of climate and tectonic activity over the past 600 ka: Evidence from a multi-story wedge in Northwest Africa","authors":"Khalil Azennoud ,&nbsp;Yassine Ait Brahim ,&nbsp;Abdennasser Baali ,&nbsp;Franziska A. Lechleitner ,&nbsp;Hicham El Asmi ,&nbsp;Xianglei Li ,&nbsp;R. Lawrence Edwards ,&nbsp;Matthew Peros","doi":"10.1016/j.sedgeo.2024.106769","DOIUrl":"10.1016/j.sedgeo.2024.106769","url":null,"abstract":"<div><div>The Quaternary Period climatic oscillations, typically those driven by Milankovitch cycles, have significantly left profound imprints in the geological records. However, the potential of terrestrial archives, particularly tufa deposits, as archives for Quaternary climate remain relatively underexplored. This study aims to contribute to filling the gap in a data-scarce region (Northwest Africa) through investigating Middle Pleistocene to Holocene groundwater-fed tufa deposits, using fieldwork-based, process-oriented facies analysis and advanced ²³⁰Th technique. Eight stratigraphic sections were measured, identifying thirteen sedimentary facies grouped into four facies associations representing specific depositional settings: (i) fluvio-lacustrine and palustrine tufa, (ii) barrage cascade tufa with buttresses, (iii) tufa in channels with pools, and (iv) tufa in shallow braided channels with free-flowing water. The depositional system comprises a single multi-story wedge of vertically and laterally stacked barrage-cascade dammed-area systems.</div><div>Our Integrated analysis revealed significant tufa growth during MIS 14, with implications for a warm and humid MISs 15–13 ‘extra-long interglacial’, consistent with multiple paleoclimate records. Such conditions would have supported late Acheulean hominin occupation and the emergence of Early Modern Humans in the region around 300 ka. The findings also highlight the possible impact of the Mid-Brunhes Event (MBE) on tufa deposition patterns, likely through CO₂-climate feedbacks, underscoring the sensitivity of tufa records to global climatic changes. Moreover, the study outcomes suggest significant regional tectonic activity during the late Middle Pleistocene, causing counter-clockwise rotation and northward tilting of MIS 14 deposits. The associated seismic events may have modified the hydrogeological budget and, by extension, altered the balance between tufa aggradation and degradation. The rotation about the vertical axis suggests a bookshelf faulting mechanism driven by regional left-lateral strike-slip tectonics. Differential karstic dissolution and tectonic forces would have further contributed to deposit tilting. The study highlights the potential of tufa as a valuable terrestrial archive for understanding Quaternary climate dynamics and tectonic processes. Future research should aim to expand the chronological framework and further investigate the climatic and tectonic influences on tufa deposition in this data-scarce region. This can be achieved through additional ²³⁰Th dating, high-resolution stable isotope measurements on microbialites, particularly focusing on the significance of the Mid-Brunhes Event (MBE) in Northwest Africa.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"474 ","pages":"Article 106769"},"PeriodicalIF":2.7,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142705947","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative characterization on multistage formation of sedimentary pyrite driven by H2S derived from biogenic process in the northeastern Ordos Basin, China","authors":"Liang Yue,&nbsp;Yangquan Jiao,&nbsp;Liqun Wu,&nbsp;Hui Rong","doi":"10.1016/j.sedgeo.2024.106768","DOIUrl":"10.1016/j.sedgeo.2024.106768","url":null,"abstract":"<div><div>Negative δ³⁴S values of sedimentary pyrite associated with organic matter are routinely assumed to be the result of biogenic process. However, the distribution and evolution of isotopic values mediated by bacteria across sedimentary strata remains poorly understood. Abundant pyrite-rich nodules (PyRNs) are distributed in the bottom of the sandstone unconformably overlying the coal in middle Jurassic strata in the northeastern Ordos Basin, providing a good opportunity to quantitatively characterize the distribution, morphology and compositions of sulfur isotope and trace element of pyrite in the sandstone influenced by organic matter in the coal. A total of 1007 PyRNs occurs within a range of 4 m from the coal. From bottom to top in the sandstone, the shape of the nodule changes from oval to round on the vertical section, and the length and number gradually decrease at the rate of ~45 mm and ~ 228 for every 1 m increase in distance, respectively. Microscopically, pyrite occurs as euhedral crystals, and trace element mapping reveals multistage growth (up to a dozen times) and a marked compositional zoning with respect to Co, Ni, As, Se and Mo. The positive correlation between Co and Ni, with ratios of Co/Ni ranging from 0.06 to 0.45, indicates that Fe and those trace elements are sourced from diagenetic fluid. The organic sulfur in coal, serving as a sulfur source, is reduced by bacteria to generate H₂³²S at a slow reduction rate. The H₂³²S migrates upwards and reacts with Fe to form pyrite in the sandstone, resulting in extremely low δ³⁴S values (from −53.9 to −43.1 ‰), which gradual decrease both from core to margin in individual grain and at the rate of 2.2 to 8.8 ‰ for every 1 m increase in distance away from the coal. This study highlights the significant variability of mineralogical (e.g., number, size, morphology) and geochemical (trace elements, sulfur isotope) characteristics of sedimentary pyrite. Results allow the relation of multistage growth of pyrite to biogenic fractionation, and provide fresh insights into biogenically derived sulfur from coals to be fixed in sandstones, which can be applied to quantitative characterization of formation processes of sedimentary minerals controlled by organic matter in sedimentary environments worldwide.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106768"},"PeriodicalIF":2.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Similar sources but distinct δ13C signatures in adjacent low-temperature travertines from Laguna Amarga (Southern Patagonian Andes)","authors":"Paulo Quezada ,&nbsp;Leonardo Fadel Cury ,&nbsp;Mauricio Calderón ,&nbsp;Carolina Henríquez ,&nbsp;Luis Mancini ,&nbsp;Joicy Micheletto ,&nbsp;Gustavo Barbosa Athayde ,&nbsp;Anelize Bahniuk Rumbelsperger","doi":"10.1016/j.sedgeo.2024.106758","DOIUrl":"10.1016/j.sedgeo.2024.106758","url":null,"abstract":"&lt;div&gt;&lt;div&gt;This study examined the waters and carbonates from two cold spring travertines (ca. 13 °C) located on the sun-exposed (north-facing travertine) and sun-shaded (south-facing travertine) margins of Laguna Amarga, an alkaline lake from the semiarid region of the eastern Patagonian Andes (51°S).&lt;/div&gt;&lt;div&gt;The travertines are composed of calcite + low-Mg calcite ± aragonite. Both exhibit similar sedimentological transitions along their longitudinal profiles. In the proximal zones, biologically-influenced carbonates form in wetland-like environments. Spherulitic calcite precipitates in association with extracellular polymeric substances in microbial biofilms containing cyanobacteria-like molds at the vent of the south-facing travertine, while aragonite spherulite formation at the north-facing travertine vent also involves sulfate-reducing bacteria, as indicated by their close association with framboidal pyrite. Downstream, in the intermediate and distal zones, crystalline dendrites predominantly precipitate due to increased turbulence-induced CO&lt;sub&gt;2&lt;/sub&gt; degassing.&lt;/div&gt;&lt;div&gt;Both travertines share a similar range of carbonate &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr composition (0.70720–0.70740) and isotopic signatures of the spring waters, including δ&lt;sup&gt;2&lt;/sup&gt;H (ca. −110 ‰ VSMOW), δ&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;water&lt;/sub&gt; (ca. −14 ‰ VSMOW) and δ&lt;sup&gt;13&lt;/sup&gt;C-DIC (ca. −5 ‰ VPDB), suggesting common sources and processes influencing fluid composition. This points to the dissolution of carbonates from mudstone-rich marine units of the Lower Cretaceous (δ&lt;sup&gt;13&lt;/sup&gt;C ca. −1 ‰ VPDB) and Upper Cretaceous (δ&lt;sup&gt;13&lt;/sup&gt;C ca. −10 ‰ VPDB) during shallow subsurface circulation of meteoric waters through the bedrock. The carbon isotopic composition of the deposits resembles those of endogenic travertines (δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;trav&lt;/sub&gt; −1.2 to 5.3 ‰ VPDB), with the highest δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;trav&lt;/sub&gt; values associated with carbonates from the vents. However, the involvement of deep CO&lt;sub&gt;2&lt;/sub&gt; sources is unclear and epigenic processes capable of producing the observed &lt;sup&gt;13&lt;/sup&gt;C enrichments are discussed.&lt;/div&gt;&lt;div&gt;Despite their common sources, similar sedimentological features and δ&lt;sup&gt;18&lt;/sup&gt;O&lt;sub&gt;trav&lt;/sub&gt; compositional range (−12.4 to −10.1 ‰ VPDB), the δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;trav&lt;/sub&gt; values are lower in the south-facing travertine (−1.2 to 1.9 ‰ VPDB) compared to the north-facing travertine (1.8 to 5.3 ‰ VPDB). This disparity is inferred to result from variations in local environmental conditions due to different levels of insolation, which favored the incorporation of soil-derived CO&lt;sub&gt;2&lt;/sub&gt; in the south-facing travertine and likely increased photosynthetic productivity in the north-facing travertine, thereby shifting their δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;trav&lt;/sub&gt; signatures to lower and higher values, respectively. These relationships highlight the sensitivity of low-temperature spring carbonates to subtle environmental changes at basin scales.&lt;/div","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106758"},"PeriodicalIF":2.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic response to event deposition and environmental disturbance in a shoreface to subaqueous delta system: Ichnology of the Silurian-Devonian Furada Formation of Asturias, Spain","authors":"Katherine Thue ,&nbsp;Luis A. Buatois ,&nbsp;M. Gabriela Mángano ,&nbsp;Mateo Ornia","doi":"10.1016/j.sedgeo.2024.106767","DOIUrl":"10.1016/j.sedgeo.2024.106767","url":null,"abstract":"<div><div>The Furada Formation of Asturias, Spain, represents a clastic shallow-marine unit deposited during the middle Silurian to the Early Devonian. This formation contains abundant evidence of event deposition and non-uniform distribution of bioturbation structures representing a benthic response to multiple stressors. The 170-m-thick succession was measured and described, and the ichnotaxa were recorded and associated with five sedimentary facies. Most shallow-marine environments are characterized by periodic events of environmental disturbance, mainly by episodic deposition, which may be recorded by a change in both the degree of bioturbation and ichnodiversity. The general depositional setting for this formation has been previously interpreted as a wave-dominated and storm-influenced shallow-marine environment. However, sedimentologic features described in this study, such as anomalous heterolithic and mudstone units, representing fluid mud layers, hyperpycnal flow deposits and plume collapse accumulations, suggest the influence of fluvial discharge, making it a more complex depositional setting. The proposed model comprises an inner sandy shoreface belt flanked seawards by a muddy subaqueous delta platform. The trace-fossil assemblages of this formation reflect environmental stress factors introduced by the interplay of storms and fluvial input (e.g., high sedimentation rate, fluctuating hydrodynamic energy, decreased substrate consolidation), resulting in reduced ichnodiversity and low abundance. From an ichnofacies perspective, the shoreface complex is characterized by the <em>Cruziana</em> Ichnofacies, whereas the subaqueous delta platform is represented by the <em>Phycosiphon</em> Ichnofacies. Integration of sedimentologic and ichnologic datasets allows for a refined depositional interpretation of the formation and greater understanding of the environmental diversity of wave-and river-influenced shallow-marine clastic systems, including the responses of the middle Paleozoic shallow-marine benthos to event sedimentation and environmental disturbance. This study is one of the first detailed documentations of the ichnology of subaqueous deltas.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106767"},"PeriodicalIF":2.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Distribution of transitional flow deposits in sedimentary environments of mixed sand-mud turbidite system","authors":"Piotr Łapcik","doi":"10.1016/j.sedgeo.2024.106766","DOIUrl":"10.1016/j.sedgeo.2024.106766","url":null,"abstract":"<div><div>Predicting facies distribution in turbidite systems is essential for resource exploration and identifying geohazards from an economic standpoint. Models that describe facies distribution depend heavily on understanding the mechanisms of particle transport and deposition. These processes are closely tied to the volume, concentration, and composition of sediment gravity flows, which display a range of behaviours between turbulent and laminar flow extremes. Recently, there has been a rise in studies on transitional flow deposits, although they remain much less understood than fully turbulent or laminar flows.</div><div>For the first time, the distribution of Structured sandstone–mudstone associated with transitional flow deposits has been quantitatively presented for various sedimentary environments within the turbidite system. The distribution of Structured sandstone–mudstone was analysed for six areas of the Ropianka Fm (Skole Nappe, Polish Outer Carpathians) across twelve sedimentary environments, including channels, channel-levees, channel-mouths, and sub-environments of the depositional lobe. An increased amount of Structured sandstone–mudstone was observed in proximal settings away from the transport axis and in the distal parts of the turbidite system. It was found that flow transformation can occur in both proximal and distal zones of the turbidite system. Structured sandstone–mudstone in proximal zones is more often deposited from diluted mud-laden flows of small volume, where fine-grained cohesive material likely underwent vertical segregation. In contrast, Structured sandstone–mudstone formed basinward tend to be initially formed by larger flows. In proximal part of depositional lobe setting, the flow transformation due to longitudinal or longitudinal and vertical segregation of fine-grained cohesive material occurs slowly. At this point the velocity of sediment gravity flow is too high and the concentration of cohesive particles is too low for common development of cohesive bonds. Flow transformation accelerates in lobe fringe and lobe distal fringe/interlobe, due to flow deceleration, changes in sand-to-mud ratio, and the time required for development of cohesive bonds and the transition to a transitional flow regime, leading to increased deposition of Structured sandstone–mudstone distally.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106766"},"PeriodicalIF":2.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical (δ13C, δ18O, 87Sr/86Sr, REEs) characterization of travertine in Tengchong, China: Insights into travertine origin and reservoir conditions","authors":"Lianchao Luo ,&nbsp;Huaguo Wen ,&nbsp;Enrico Capezzuoli ,&nbsp;Sándor Kele ,&nbsp;Orlando Vaselli ,&nbsp;Zhipeng Lu ,&nbsp;Yaxin Xu ,&nbsp;Huixuan Huang ,&nbsp;Lei Du ,&nbsp;Andrea Brogi","doi":"10.1016/j.sedgeo.2024.106759","DOIUrl":"10.1016/j.sedgeo.2024.106759","url":null,"abstract":"<div><div>Geochemical characterization is extensively employed in travertine research, yet few studies have explored the potential of travertine geochemistry for elucidating the subterranean details of spring systems. In this study, we systematically characterized the geochemical signatures (δ¹³C, δ¹⁸O, ⁸⁷Sr/⁸⁶Sr, REEs, Zr, Th, Sr, Mn) of travertine from six spring systems in Tengchong (SW China) and compared them with those of potential reservoir rocks, aiming to understand travertine origin and assess reservoir conditions. Our results revealed substantial variations in the δ¹³C and δ¹⁸O of travertine among the examined systems, but the water temperature and parent CO₂ assessments suggest a hot spring thermogene origin of the travertine. The ⁸⁷Sr/⁸⁶Sr of the studied travertine also varies significantly among the systems and overlaps with that of potential reservoir rocks. However, only the springs systems with reservoir temperatures exceeding 150 °C are likely to have precipitated travertine with ⁸⁷Sr/⁸⁶Sr resembling the whole-rock ⁸⁷Sr/⁸⁶Sr of the reservoir rocks. REE contamination by exogenous detritus and Fe<img>Mn (oxyhydr)oxides was noted, emphasizing the need for careful REE contamination evaluation in travertine research. The REE comparison reveals that the studied travertine does not fully replicate the REE signature of its potential reservoir rocks, but the REE pattern, (Eu/Eu*)_SN, and (Ce/Ce*)_SN characteristics of the travertine reveal informative reservoir conditions. In summary, this study shows that the geochemistry of the travertine offers valuable insights into its origin and reservoir conditions. These findings could assist in the geochemical interpretation of travertine and the exaction of hypogean reservoir conditions from travertine.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106759"},"PeriodicalIF":2.7,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142553150","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying paleoecological impact of the OAE1a on shallow marine ecosystems from southeastern France","authors":"Alexis Godet ,&nbsp;Jacob Byerly ,&nbsp;Matthew Bourdon ,&nbsp;Marina Suarez","doi":"10.1016/j.sedgeo.2024.106757","DOIUrl":"10.1016/j.sedgeo.2024.106757","url":null,"abstract":"<div><div>Climate and environmental instability during the early Aptian culminated with the unfolding of the Oceanic Anoxic Event (OAE) 1a, which resulted in the deposition of black shales in deep marine settings and a typical negative spike followed by a positive excursion in δ¹³C values. In Vercors (southern France) the Urgonian platform developed prior to and coeval to the OAE1a, but the impact of this paleoenvironmental crisis on the ecology of benthic ecosystems is yet to be quantified. We gathered field and petrographic data to identify sequence boundaries and maximum flooding surfaces that are biostratigraphically dated and correlated between four localities within the study area. A composite δ¹³C curve is built where the C3 to C7 isotope segments from the literature are identified, pinpointing the onset of the OAE1a above the last episode of deposition of Urgonian facies rich in rudist bivalves. Furthermore, thin section point counting data are used to quantify the proportion of allochems in samples and to trace changes in the ecology of ecosystems. The principal component analysis of point counting data helps define ecological tiers: a diversified, photozoan association with rudists, green algae, and benthic foraminifera dominated ecosystems before the OAE1a and up to the C7 segment, while a less diversified heterozoan association with bryozoans and crinoids developed after the OAE1a. To explore the triggers for this change, the principal component analysis of elemental geochemical data highlights an increased nutrient and detrital input as major triggering mechanisms for ecological adjustments and changes in the biodiversity of ecosystems. In particular after the OAE1a, an increase in detrital and nutrient input leads to the replacement of photozoan by heterozoan assemblages more adapted to these stressful conditions. This research directly links paleoenvironmental deterioration to paleoecological changes and quantifies the amount of adaptation of ecosystems.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"473 ","pages":"Article 106757"},"PeriodicalIF":2.7,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142533338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Facies architecture, pedogenesis and palynology of the Olenekian dryland setting – A sedimentary record of Early Triassic climate oscillations in the SE Germanic Basin","authors":"Karol Jewuła ,&nbsp;Wiesław Trela ,&nbsp;Artur Kędzior ,&nbsp;Anna Fijałkowska-Mader ,&nbsp;Natalia Wasielka","doi":"10.1016/j.sedgeo.2024.106754","DOIUrl":"10.1016/j.sedgeo.2024.106754","url":null,"abstract":"<div><div>The Early Triassic period was characterised by significant climatic perturbations driven by generally high global temperatures. Several significant shifts in the stable carbon and oxygen isotopes were recognised in the marine settings in the Olenekian age deposits that were linked to short-lasting but relatively high-amplitude climatic events. The record of these events in the continental strata is far less understood due to the stratigraphic incompleteness of such deposits. However, in the Holy Cross Mountains (Poland), the Olenekian continental deposits are well preserved, and sedimentation was relatively continuous, making them an ideal candidate for studying the effects of climate changes and their preservation in continental settings. As such, sedimentological analysis of five wells and one outcrop (over 530 m logged in total), integrated with new and legacy palynological data, allowed the reconstruction and dating of major steps in the palaeoenvironmental evolution of the SE part of the Central European (Germanic Basin), and its comparison with the marine-based climatic models for the Early Triassic. The lower and middle Olenekian stage is represented by fine-grained deposits of dry floodplain interbedded with sandstones deposited within fluvial distributary channels and terminal splays. The palaeosols are mainly represented by aridisols (calcisols), indicating a relatively dry, though not extreme, climate as some water was necessary to support relict plant cover. Towards the mid-Spathian times, the climate became more humid - lacustrine deposits appeared, and palaeosols displayed features of an elevated water table (gleyed vertisols and inceptisols). Frequent storms and floods also affected the lacustrine sedimentation, reflecting volatile climatic conditions. In the late Spathian time, continental sedimentation continued, and the dominance of vertisols and more stacked fluvial channels in the sequence is linked with an increased seasonality, with more pronounced humid seasons. The continental setting lasted until the latest Spathian time, when a marine transgression occurred, marking a new phase in the basin development.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"472 ","pages":"Article 106754"},"PeriodicalIF":2.7,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142419012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}