Sedimentary Geology最新文献

{"title":"Coastal dynamics and sea-level change at 4 ka: A case study from the Wakayama Plain, Japan","authors":"Susumu Tanabe ,&nbsp;Kanata Kobayashi ,&nbsp;Toshiaki Irizuki ,&nbsp;Akira Tsujimoto ,&nbsp;Rei Nakashima ,&nbsp;Yuki Haneda ,&nbsp;Yoshiro Ishihara","doi":"10.1016/j.sedgeo.2025.106807","DOIUrl":"10.1016/j.sedgeo.2025.106807","url":null,"abstract":"<div><div>Coastal depositional systems can be classified into transgressive and regressive systems, but their dynamics in relation to multi-segment sea level change remains largely unknown. In this study, we examined five sediment cores and 57 radiocarbon dates from the Wakayama Plain, western Japan. We have elucidated that the maximum flooding surface is dated at 7.6 cal kyr BP (8 ka), and the depositional system changed from a wave-dominated estuary to a wave-dominated delta at around 4 ka. This two-step change in the coastal depositional system can be explained by the decreasing in the rate of sea-level rise at 8 ka and the onset of sea-level fall at 4 ka, respectively. The coastal dynamics of the Wakayama Plain suggests that in areas where the mid-Holocene sea-level was higher than present sea levels, the sediment stacking pattern was controlled by the “rate” of sea-level rise, and the change in the geometry of the depositional system was controlled by the “height” of sea level.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106807"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143176572","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":"Architectures of the turbidite channel in the head area of a slope-parallel directional submarine turbidite channel system: A case study of the Central Canyon Area, Qiongdongnan Basin, South China Sea","authors":"Chao FU ,&nbsp;Yuhong XIE ,&nbsp;Hui WANG ,&nbsp;Wei XU","doi":"10.1016/j.sedgeo.2024.106801","DOIUrl":"10.1016/j.sedgeo.2024.106801","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Significant volumes of sediment are deposited in deep-sea regions via turbidite channel systems, which function as critical conduits for the transport of sediment from shelf environments to the abyssal plain; concurrently, complex sedimentary processes—such as erosion, incision, and sedimentation—play an integral role in the development of diverse architectural features. In particular, the head area of slope-parallel submarine turbidite channel systems is marked by significant sediment transport, yet the rapidly changing topography has limited our understanding of their architectural stacking patterns. In this study, we selected the head area of the Central Canyon Area (CCA) in the Qiongdongnan Basin (QDNB) as a case study and constructed various patterns of turbidite channel system architecture along the turbidity flow direction. Based on &gt;200 m of core samples, we identified nine lithofacies and determined the transition patterns of turbidite flows from coarse-grained equilibrium flow, fine-grained equilibrium flow, depositional flow, and erosion flow. Furthermore, utilizing high-resolution 3D seismic data, we measured the geomorphological parameters of the channel systems, including the static aspect ratio, cross-sectional asymmetry, angles of channel-complex growth trajectories, and stratigraphic mobility numbers. By applying an empirical formula that correlates turbidite channel system morphology with layer-averaged flow velocity, we calculated the corresponding Froude numbers. Finally, we reconstructed the evolution of the turbidite channel system architecture in different hierarchies.① In the initial depositional stage, coarse-grained and fine-grained equilibrium flows developed. The turbidite channel system complex presented high aspect ratios and asymmetry values in upstream depocentre areas, transitioning to lower aspect ratios in midstream regions while maintaining high asymmetry. This architecture is characterized by steady vertical accretion types, with the predominant filling types being layer-filled, cut-stack, and interbedded mass transport deposits (MTDs). ② During the rapid accumulation stage, a shift to lower aspect ratios and asymmetry values occurs, revealing diverse turbidite channel systems, primarily lateral accretion types with layered filling, lateral products, and cut-stack patterns dominating the channel stacks. ③ In the reworking MTD stage, a sharp change in the aspect ratio signals a dominance of lateral accretion-type channel systems interbedded with MTDs.&lt;/div&gt;&lt;div&gt;Furthermore, we identify key factors influencing the architecture of turbidite channel system stack patterns across different stages and speculate on deposition patterns in slope-parallel submarine channel heads. Statistical analysis of the morphological parameters revealed that during the initial deposition and rapid accumulation stages, the topographic slope angle and turbidity currents were the primary influences on channel accumulation. ","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106801"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143176772","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":"Rapid subsidence as a driver of phosphate deposition in the later Ordovician: Case study from the Alabama Appalachians","authors":"John T. Haynes ,&nbsp;Rafael A. Villanueva ,&nbsp;Richard M. Robinet ,&nbsp;Stephen A. Leslie ,&nbsp;Achim D. Herrmann","doi":"10.1016/j.sedgeo.2024.106783","DOIUrl":"10.1016/j.sedgeo.2024.106783","url":null,"abstract":"&lt;div&gt;&lt;div&gt;An increase in accumulation of phosphate-enriched sediment occurred in several areas of Earth's oceans during the later Ordovician, suggesting that some fundamental change (s) in seawater and/or pore water chemistry were taking place, either syndepositionally or during early diagenesis. One hypothesis is that widespread cooling of the water column led to this increase, but another is that the increase could have been forced primarily by changes in seawater chemistry that accompanied an influx of siliciclastic sediments associated with tectonically driven subsidence. Here, we report on findings from study of the upper ~30 m of the &gt;200 m of Middle and Late Ordovician strata exposed near Tidwell Hollow, Blount County, Alabama, and what the results suggest about the competing hypotheses. This Ordovician sequence, deposited along the southeastern margin of Laurentia during the initial (Blountian) stage of the Taconic Orogeny, records the transition from a restricted peritidal carbonate shelf environment (the “Black River lithofacies”) into a more normal marine carbonate environment (the “Trenton lithofacies”). In particular, the younger carbonate strata are notable for their measurably higher amounts of secondary phosphate minerals. This stratigraphic interval is also well-constrained chronostratigraphically by the presence of the Deicke and Millbrig K-bentonite beds (altered volcanic tephra layers), thus it is ideal for a focused geochemical, petrographic, and stratigraphic investigation of the increased phosphate content of a specific Upper Ordovician sequence. Analyses of bulk rock samples and of extracted collophane grains (via x-ray fluorescence, XRF, and in-situ laser ablation inductively coupled plasma mass spectrometer, ICPMS) suggest that phosphogenesis in these strata was episodic rather than slow and steady, with a depositional pattern of abrupt increases followed by abrupt declines. Observed trace element changes in the 12 m to 18 m sample interval include the occurrence of elevated Th/U ratios (maximum of 5.7) accompanied by Y/Ho ratios that range from 27 (base) to 51 (top). We attribute these changes to increasing silicate influx into the basin and an accompanying increase in available Fe, which would preferentially scavenge MREEs and then release them to the pore waters leading to MREE enrichment, which we also observe in this interval. In a rapidly subsiding basin, MREE enrichment could have resulted from initial restriction of bottom water circulation followed by gradually more open marine conditions. Some allochems and textures that are more characteristic of the older Black River lithofacies than the younger Trenton lithofacies (e.g. framework grains of calcareous green algae and Type 1 and Type 2 oncoids, fenestral lime mudstones, and associated small framestones of &lt;em&gt;Tetradium&lt;/em&gt; sp. buildups) persist in relative abundance upsection into the ~10 m interval of strata above the Millbrig K-bentonite Bed, and this pe","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106783"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143177192","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":"Net-0 experimental procedure to obtain Ca‑carbonate bio-cement via microbially induced precipitation in a fluvial natural lab","authors":"Edoardo Perri ,&nbsp;Mario Borrelli ,&nbsp;Maurizio Ponte","doi":"10.1016/j.sedgeo.2024.106803","DOIUrl":"10.1016/j.sedgeo.2024.106803","url":null,"abstract":"<div><div>Despite laboratory reproduced microbially induced Ca‑carbonate precipitation is currently used for various sustainable bio-engineering applications, an inevitable environmental impact because of the waste materials and chemicals involved in lab activities still occurs. Here is presented a new and alternative net-0 experimental procedure to obtain a Ca‑carbonate bio-cement, developed in a natural fluvial laboratory (Parmenta stream) where microbial-mediated calcite precipitates, forming typical tufa deposits. The experiment consisted in the treating of a common multimineral sand (0,355–1 mm in grain size) with the stream flowing water for 4 months, associated with a parallel control monitoring of the precipitation process. During this time interval, thanks to the development and mediation of the microbial biofilm community, calcite precipitated with a variable daily rate from 0,49 to 2,94 μm/day, showing typical hierarchical nano- to micro-crystalline morphological features. This process brought to the gradual formation of a calcite bio-cement around the sand particles, starting from scattered tens of μm-size crystal aggregates to continuous crusts up to ca. 200 μm thick. The internal friction angle of the sand showed a total increase of ca. 20 % (i.e. 5,9° from 28,6° to 34,5°), with the major growth of ca. 16 % (i.e. 4,8° from 28,6° to 33,4°) after just 1 month; this indicates that just few amounts of new precipitates are enough to obtain the 80 % of such increase, most probably due to the roughness rise of the grains. Whereas, the cohesion showed a constant reduction trough time up to a total of ca. -64 % (from 0,17 Kg/cm² to 0,06 Kg/cm²); this probably due to a reduction of the grains' specific surface on which the electrostatic attractions act.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106803"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175057","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":"In-situ sulfur isotope characteristic and genesis of sedimentary pyrite with varying crystal morphologies in coal-bearing strata in North China","authors":"Lihui Liu ,&nbsp;Sen Wang ,&nbsp;Zhanjie Xu ,&nbsp;Tianjiao Yu ,&nbsp;Joan S. Esterle ,&nbsp;Suzanne D. Golding ,&nbsp;Yunfei Xi ,&nbsp;Qinfu Liu","doi":"10.1016/j.sedgeo.2024.106805","DOIUrl":"10.1016/j.sedgeo.2024.106805","url":null,"abstract":"<div><div>Sedimentary pyrite is ubiquitous in coal measures and occurs with different crystal morphologies and geochemical characteristics that are typically employed to infer the bottom seawater microenvironment and diagenetic stages. In this study, representative pyrite with four distinct crystal morphologies were identified in Carboniferous coal gangue in North China. The crystal structure, microscopic morphology, <em>in-situ</em> sulfur isotope content, and distribution of pyrite crystals were comprehensively analyzed using polarizing microscopy, X-ray diffraction, scanning electron microscope, and nanoscale secondary ion mass spectrometry to better understand the diagenetic evolution of these Carboniferous rocks. The varying morphologies and δ³⁴S values of pyrite closely correlate to the crystal growth pattern, sulfur source, and precipitation mechanism. Euhedral granular pyrite and framboidal pyrite have relatively small particle sizes and negative δ³⁴S values (average − 6.59 ‰ and − 36.62 ‰) and are interpreted to have formed through the reduction of sulfate in a brackish lagoon from the <em>syn</em>-depositional stage to the early diagenetic stage. In contrast, massive pyrite and cell-filling pyrite exhibit slightly larger particle size and positive δ³⁴S values (average + 9.39 ‰ and + 10.53 ‰), which suggest formation in the diagenetic stage under the action of microbial sulfate reduction. The geochemical characteristics recorded in the microscale pyrites indicate that the primary sulfur source is seawater sulfate where the wide range of pyrite sulfur isotope values reflects substrate depletion effects in an increasingly closed system. This research highlights the vital relationship between grain shape and the mechanism of sedimentary pyrite formation in the coal-forming environment. Thus, different pyrite mineralization processes in the world can be identified, and the environment of crystal growth understood by <em>in-situ</em> sulfur isotope analysis.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106805"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175054","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":"Lithification of pelletal grains by microbially mediated organomineralization","authors":"Mara R. Diaz ,&nbsp;Kelly Bergman ,&nbsp;Peter K. Swart ,&nbsp;Gregor P. Eberli","doi":"10.1016/j.sedgeo.2024.106785","DOIUrl":"10.1016/j.sedgeo.2024.106785","url":null,"abstract":"<div><div>Fecal pellets are key components of the biological carbon pump and a source of nutrients. When cohesively bound and cemented, they become the most abundant non-skeletal grains in shallow-water carbonates and an important nucleus for ooid formation. Herein, we describe the mineralization processes contributing to pellet cementation using scanning electron microscopy in conjunction with stable isotope and mineralogical analyses of the bulk sediments on Great Bahama Bank, known for its abundance of peloids and fecal pellets. Results show biogenic signatures consistent with the initial stages of organomineralization. These include, curved-tubular filaments and bacilli bacteria associated with extracellular polymeric substances (EPS); fibrils of EPS binding aragonite needles; and the coexistence of decayed EPS with amorphous calcium carbonate that once it develops, coalesces and crystalizes into aragonite. While δ¹³C_inorg do not show large variations, slightly higher values are observed in areas where pellets are indurated, likely attributed to photosynthetic activity on the pellets. The δ¹³C_org values tend to be more elevated in indurated pellets, suggesting that heterotrophs are preferentially using enriched carbon sources. In contrast, friable pellets from nearshore areas show more negative δ¹³C_org values, suggesting microbial exposure to depleted C3 and CAM plant sources. Fingerprints of nitrogen fixation and denitrification are also documented and supported by δ¹⁵N_org values. Altogether, these findings suggest that EPS and a microbial consortium, including gut-microbial flora and free-living surface colonizers, are responsible for inducing early cements, which are later complemented by secondary cements. Microorganisms involved in pellet lithification may subsequently also aid in ooid cortex development.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106785"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143176571","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":"Sedimentation patterns from turbidity currents associated to hydrodynamical transport modes","authors":"Teresa Serra,&nbsp;Marianna Soler,&nbsp;Jordi Colomer","doi":"10.1016/j.sedgeo.2024.106802","DOIUrl":"10.1016/j.sedgeo.2024.106802","url":null,"abstract":"<div><div>Turbidity currents are mechanisms that transport sediment from continental landscapes into coastal areas and therefore into oceans, reservoirs and lakes. Turbulence at the head of the turbidity current maintains sediment particles in suspension provided the mixing is greater than the settling velocity of the particles being transported. However, both the depositional regimes of the particles in turbidity currents and the extent of the hydrodynamical regimes still need to be better related. Likewise, the associated sedimentary patterns need to be related to the type of particles that form a turbidity current. In this study, a set of lock-exchange experiments in a flume were conducted to determine the extent and development of a turbidity current composed of different granulometric sediments and sediment concentrations. Both the extent of the inertial regime and the onset of the self-similar regime were determined and found to be dependent on the d₅₀ of the sediment and the Rouse number (i.e. the balance between particle sedimentation and mixing due to the gravity current development). The results obtained from the sedimentation patterns bring new knowledge in explaining the gradation of sediments in turbidites and its relationship to the longitudinal hydrodynamics of a turbidity current as it develops.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106802"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143175058","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":"Distinct grain-size patterns in sandy turbidites: Implications for identifying the triggers of ancient turbidity currents in lacustrine settings","authors":"Peng Chen ,&nbsp;Benzhong Xian ,&nbsp;Meijun Li ,&nbsp;Junhui Wang ,&nbsp;Yang Peng ,&nbsp;Guodong Zhang ,&nbsp;Rongheng Tian ,&nbsp;Qianran Wu ,&nbsp;Jianping Liu ,&nbsp;Pengfei Xiang ,&nbsp;Chengshan Wang","doi":"10.1016/j.sedgeo.2025.106806","DOIUrl":"10.1016/j.sedgeo.2025.106806","url":null,"abstract":"<div><div>Understanding the triggers of turbidity currents from their deposits is crucial to constraining past climate and environmental changes, reconstructing tectonic or seismic activities, and predicting submarine geohazards. However, it is challenging to determine the origin of turbidites when the examined interval cannot be correlated with historically known events or exhibits no lithofacies characteristics. Such work has therefore been performed mainly toward modern turbidites as they are better correlated with recorded events than ancient turbidites. Here we identified two distinct grain-size patterns based on detailed grain-size analysis of the Triassic sandy turbidites in the Ordos Basin. The two patterns vary significantly in sorting and slope value of one-dimensional linear regression equations in the coarsest versus the median grain size (<em>D</em>₉₉–<em>D</em>₅₀) diagram. Poorer sorting with lower slope value (0–1) is interpreted to be river flood-triggered turbidite, whereas better sorting with higher slope value (&gt;1) is interpreted to be slope failure-triggered turbidite. This interpretation is then evaluated by comparison to modern turbidites of known origin. This study suggests that even if the lithofacies are very similar, turbidites with different origin can display distinct grain-size patterns, reflecting fluctuations in source materials, flow capacity and velocity of their original turbidity currents. It also provides a new insight into identifying the triggers of ancient turbidity currents using grain-size data.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"476 ","pages":"Article 106806"},"PeriodicalIF":2.7,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143176573","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":"The migration pattern of oxidation fluids and its constraints on uranium mineralization in the Tamusu sandstone type uranium deposit of the Bayingobi Basin, China","authors":"Chengyong Zhang ,&nbsp;Fei Xia ,&nbsp;Wei Deng ,&nbsp;Xu Liu ,&nbsp;Qunxi Zhang ,&nbsp;Beibei Shi ,&nbsp;Haixiao Li ,&nbsp;Yukun Fu","doi":"10.1016/j.sedgeo.2025.106823","DOIUrl":"10.1016/j.sedgeo.2025.106823","url":null,"abstract":"<div><div>Exploring the developmental stages and migration patterns of oxidation zones has always been a key task in the exploration of sandstone uranium deposits, but the involvement of deep fluid activity often makes it difficult to determine the characteristics of oxidizing fluids. The Tamusu deposit is a large sandstone-host uranium deposit, characterized of large scale oxidation zone, multiple layers of ore bodies, dense sandstone, and obvious hydrothermal alteration. However, the stage and mechanism of the occurrence of oxidative fluids are still unclear. Identifying the stages and migration patterns of oxidizing fluids and determining their relationship with uranium enrichment are of great significance for revealing the genesis of mineral deposits and exploring uranium deposits in other similar basins. In this study, core observation, microscopy, electron probe, scanning electron microscopy, cathodoluminescence, and <em>α</em> track etching were used to study the distribution of oxidation zones, the formation sequence of altered minerals, and uranium mineralogical characteristics. The oxidation zone occurs on a large scale in the upper member of the fan delta sand body, with almost all disappeared at the interface between sandstone and mudstone, and the oxidation fluid migration also occurs in many fractures of the target layer. The altered minerals in the Tamusu deposit mainly include hematite, limonite, dolomite, ankerite, gypsum, pyrite, and other metal sulfides. The uranium minerals in the ore are mainly pitchblende, some coffinite and U<img>Ti mixture，with a small amount of secondary uranium minerals. Uranium minerals are mainly distributed on the surface of debris particles, around pyrite or carbon debris, as well as in dissolution pores or growth zones of ankerite. The sedimentation and alteration of Tamusu sandstone can be divided into 4 stages: sedimentation to early diagenesis stage, early large-scale oxidation stage, thermal fluid alteration stage, and late weak oxidation stage. The sandstone with excellent pores in the early diagenetic stage and the unobstructed groundwater recharge, runoff, and drainage system are the main reasons for the formation of large-scale oxidation. At the end of the Early Cretaceous, hydrothermal activity formed a large amount of dolomite, ankerite, gypsum, etc., which solidified the sandstone and terminated the migration of oxidizing fluids in the pores of the sandstone. After the consolidation of sandstone, the oxidized fluid mainly migrated along the fractures in the formation, or also transformed some early consolidated sand bodies near the edge of the basin, and the oxidation scale significantly weakened. Therefore, the Tamusu deposit experienced three main stages: Large scale oxidation and low-grade U formation stage，hydrothermal alteration and U mineralization and late oxidation weak uranium mineralization stage.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"478 ","pages":"Article 106823"},"PeriodicalIF":2.7,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143348609","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":"Evolution of lithic clasts in a subaquatic debris flow: Conclusions from the Rzucewo site, Poland","authors":"Łukasz Elwirski,&nbsp;Piotr Paweł Woźniak","doi":"10.1016/j.sedgeo.2025.106822","DOIUrl":"10.1016/j.sedgeo.2025.106822","url":null,"abstract":"<div><div>Research on clast evolution in subaquatic debris flows is rare and experiments on this issue are insufficient due to technical limitations. To fill this knowledge gap, we identify the determinants of morphological and lithological diversity of pebbles in Late Pleistocene deposits of subaquatic debris flows. The advantage of the study site is the ability to trace these aspects along the entire cross-section of the subaquatic fan, which is unique. Lithology, size, form (using Sneed and Folk's method), and roundness (using Powers' method) of pebbles ranging in size from 20 to 60 mm in two debrites were analysed. Additionally, the grain size composition of debrites was determined through wet sieving. As a result of inheritance from debris transported in the ice, the majority of pebbles in all samples show lithology similar to the till of the same age and a form close to sub-equant. A downslope increase in the share of more oblate and prolate clasts is recognized, which is explained by the transfer of pebbles more susceptible to buoyancy to the debris-flow front. This may mimic clast form changes caused by abrasion. Moreover, a tendency to transfer the largest pebbles can be observed. The roundness of pebbles increases along with the debris-flow route, despite its relatively short length, mainly due to friction against matrix and collisions with other coarse particles. This trend is observed in different petrographic groups of rocks, regardless of their abrasion resistance. It is most likely that the rotation of pebbles has helped in smoothing out their edges and faces. Our results show that a moderately dynamic environment, with a slope angle relatively smaller compared to experiments using flume channel, but a debris-flow distance similar to those studies, can alter the morphology of pebbles. While experiments focus on subaerial environments, the findings appear to be useful in studies of subaquatic debris flows.</div></div>","PeriodicalId":21575,"journal":{"name":"Sedimentary Geology","volume":"477 ","pages":"Article 106822"},"PeriodicalIF":2.7,"publicationDate":"2025-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143092915","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}