Palaeogeography, Palaeoclimatology, Palaeoecology最新文献

{"title":"Making sense of variation in sclerochronological stable isotope profiles of mollusks and fish otoliths from the early Eocene southern North Sea Basin","authors":"Johan Vellekoop ,&nbsp;Daan Vanhove ,&nbsp;Inge Jelu ,&nbsp;Philippe Claeys ,&nbsp;Linda C. Ivany ,&nbsp;Niels J. de Winter ,&nbsp;Robert P. Speijer ,&nbsp;Etienne Steurbaut","doi":"10.1016/j.palaeo.2024.112627","DOIUrl":"10.1016/j.palaeo.2024.112627","url":null,"abstract":"<div><div>Stable isotope sclerochemistry of biogenic carbonate is frequently used for the reconstruction of paleotemperature and seasonality. Yet, few studies have compared intra-and inter-taxon isotope variability and variation within a single depositional environment. We measured seasonal changes in δ¹⁸O and δ¹³C compositions in multiple specimens of two carditid bivalve species, a turritelline gastropod species, and two species of otoliths from demersal fish, from two early Eocene (latest Ypresian, 49.2 Ma) coquinas in the inner neritic Aalter Formation, located in the Belgian part of the southern North Sea Basin (paleolatitude ∼41°N). Results demonstrate considerable variation among taxa in the mean, amplitude, and skewness of δ¹⁸O and δ¹³C values from sequentially sampled growth series. We attribute this variation to factors including differences in seasonal growth over ontogeny, mixing of depositional settings by sediment transport, differences between sedentary and mobile organisms, and differences in longevity of the taxa in question. Growth cessation during winters in turritellines and fishes in particular lead to an incomplete representation of the seasonal cycle in their growth increments, in comparison to carditid bivalves. Ophidiid fish otolith isotope records appear to reflect environmental conditions over a wider range of habitats and environments, and we infer this is due to a combination of sedimentary transport, as these are small structures, and postmortem transport by free-swimming predatory fish. Our study highlights the potential variability encompassed by taxa in the shallow marine realm even when they are found in the same deposits. While this has significant implications for seasonality reconstructions based on conventional isotope profiles, we show that careful study of the ecology and ontogeny of multiple taxa and specimens within a death assemblage can reveal sources of variation and yield a close approximation of conditions in the setting of interest.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112627"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160295","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":"Organic matter sources, accumulation and diagenesis of the Lontras Shale Lagerstätte (Paraná Basin, southern Brazil)","authors":"Alexandre Ribeiro Cardoso ,&nbsp;Jaques Soares Schmidt ,&nbsp;Eduardo Müller Bernardes ,&nbsp;Anderson José Maraschin ,&nbsp;Débora de Coelho Andrade ,&nbsp;Filipe de Medeiros Albano ,&nbsp;Gabriel Rübensam ,&nbsp;Gustavo Bombardelli Barp ,&nbsp;Juliana Nichele Kich ,&nbsp;Naira Poerner Rodrigues ,&nbsp;Yasmin Felix de Oliveira ,&nbsp;João Pedro Tauscheck Zielinski ,&nbsp;Luiz Carlos Weinschütz ,&nbsp;Joselito Cabral Vazquez ,&nbsp;Felipe Dalla Vecchia","doi":"10.1016/j.palaeo.2024.112661","DOIUrl":"10.1016/j.palaeo.2024.112661","url":null,"abstract":"<div><div>The Lontras Shale Lagerstätte (LSL) is an exceptional fossil site recording paleoenvironmental/paleoecological changes developed over the Late Paleozoic Ice Age. The succession consists of 1.15 m-thick organic-rich shales hosting abundant and diverse fossil specimens from terrestrial and marine origin, representing the Pennsylvanian-Permian of the Paraná Basin, southern Brazil. Most studies about the LSL focused on the paleontological content, whereas the depositional setting has been over debate, and the diagenetic history stands underexplored. Petrographic, organic and inorganic geochemical approaches were applied in the reconstruction of the organic matter sources, paleoenvironment and diagenetic evolution of the LSL. The Lagerstätte is composed of structureless to laminated mudstones, with increasing amounts of phytoclasts and siliciclastic grains upsection. Silica cement, biostructured organic matter and sphere-shaped microfossils occur at the lowermost level. SEM/EDS imaging reveals soft tissues, smectite flakes, framboidal pyrite, euhedral sanidine and authigenic chlorite rosettes. δ¹³C_VPDB values range between ̶ 26.76 ± 0.14 ‰ and ̶ 24.39 ± 0.13 ‰, whereas kerogen type II predominates, and kerogen type III only occurs in the topmost level. Petrographic and geochemical data demonstrate mixed terrestrial and marine contributions of organic matter. Paleoredox proxies depict anoxic-dysoxic conditions, whereas paleosalinity proxies constrain brackish conditions (TS/TOC &lt; 0.5). Limited stratigraphic and geographic distribution of the LSL, mixed fossil assemblages and geochemical signatures indicate accumulation in a restricted marine setting. Deglaciation-induced meltwaters caused seasonal inputs of nutrients and sporadic oxygen renewal during summer/spring periods. Conversely, winter periods experienced scarcer inflows, resulting in a shallow halocline, anoxia-euxinia and mass mortality events. Undeformed grains, immature kerogen, vitrinite reflectance (0.48–0.58 %), and peak temperatures (421–432 °C) demonstrate shallow burial, coherent with the immature thermal zone. Chlorite rosettes and euhedral sanidine precipitated during mesodiagenesis, after increasing burial depths. Coincidental distribution of microfossils, biostructured organic matter and eodiagenetic silica suggest bioinduced silicification, revealing a new taphonomic pathway to the LSL.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112661"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160327","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":"Vegetation and climate history during the Last Interglacial on the Istrian coast (Northern Adriatic Sea)","authors":"M.D. Novellino ,&nbsp;A. Fontana ,&nbsp;P. Bertuletti ,&nbsp;G. Furlanetto ,&nbsp;R. Pini ,&nbsp;I. Felja ,&nbsp;M. Juračić ,&nbsp;C. Ravazzi","doi":"10.1016/j.palaeo.2024.112671","DOIUrl":"10.1016/j.palaeo.2024.112671","url":null,"abstract":"<div><div>The dynamics of Mediterranean-type ecosystems through the Last Interglacial (LIG) period are still poorly understood due to sparse records from fossil sites located in the coastal regions of Southern Europe. Here we present the first high-resolution multiproxy record from the infill of a karst estuary in the Istria Peninsula, northern Mediterranean borderlands. Our research explores the potential of the MIR1 core sediments as an archive of the sedimentary history, terrestrial vegetation, climate oscillations and sea-level changes from Termination II (TII) to the decline of the LIG optimum. Due to the absence of absolute ages, the timing was obtained by the correlation of biostratigraphical and climate events. We reconstructed major ecosystem changes from open vegetation of semideserts, steppe/forest steppe, and xerophytic scrub thriving during Termination II (i.e., penultimate deglaciation) to the interglacial spread of woodlands at the Last Interglacial onset. Here, the MIR1 record shows the abrupt expansion of deciduous and semi-evergreen oaks, mirroring a climatic event well depicted in oxygen isotopic records from Alpine speleothems around 129.7 ka. Fire played a relevant role in ecosystem dynamics during both TII and early LIG, owing to plant biomass abundance that triggered fires and favoured their spread. However, fires were never stand-replacing, but determined short-lived fluctuations in ecosystem structure. During the subsequent LIG optimum, Mediterranean sclerophyll forests largely developed in the coastal areas, whereas the Istrian inland hosted moist-demanding species preferring cooler winters. In the Alps, the decline of the LIG optimum occurred at an estimated age of ca 127.5 ka, but was only partially recorded in the MIR1 due to sequence truncation; nonetheless, it features the demise of sclerophyll communities and the increase of <em>Carpinus betulus</em> and <em>Fagus</em>. Micropaleontological indicators of sea-level change help to reconstruct sedimentary environments linked with the LIG sea-level rise, providing a full comprehension of the sedimentation process.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112671"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160290","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":"Sclerochronology and oxygen isotope variations in modern Conomurex luhuanus shells: An archive for reconstructing palaeotemperature and shellfish gathering on the Great Barrier Reef, Australia","authors":"Mahsa Alidoostsalimi ,&nbsp;Amy L. Prendergast ,&nbsp;Sean Ulm ,&nbsp;Russell N. Drysdale ,&nbsp;Josephine Brown ,&nbsp;Robert M. Klaebe ,&nbsp;Bohao Dong ,&nbsp;Nguurruumungu Indigenous Corporation ,&nbsp;Walmbaar Aboriginal Corporation RNTBC","doi":"10.1016/j.palaeo.2024.112633","DOIUrl":"10.1016/j.palaeo.2024.112633","url":null,"abstract":"<div><div>The marine gastropod <em>Conomurex luhuanus</em> is a common component of Holocene archaeological shell deposits in the Western Indo-Pacific region. Oxygen isotope ratios recorded in shells of <em>C. luhuanus</em> from the Great Barrier Reef potentially provide high-resolution data on palaeoclimatic conditions and the exploitation of coastal marine resources. However, the application of this species as a palaeoclimate and seasonal foraging archive has yet to be investigated. We employ sclerochronology techniques to analyse oxygen isotope variations in modern, live-collected shells to evaluate the efficacy of this species in recording modern environmental factors, such as sea-surface temperature (SST). We collected live <em>C. luhuanus</em> during the cold season (August and September), in two separate years (2019 and 2023), from reef-flat intertidal zones. Shell growth increments were studied in section and high-resolution carbonate samples were collected from the lip portion and along the body whorl to test whether shell carbonate is deposited in oxygen isotopic equilibrium with seawater and to decipher the shell growth pattern of this species. Measured δ¹⁸O_shell ranges between −0.2 and −1.8 ‰ (VPDB) in modern samples. Despite showing variability in growth rates, including a remarkable growth stop/slowdown during the cool season that is punctuated by a red zone with closely spaced growth increments, our findings reveal that <em>C. luhuanus</em> deposits its aragonite shells at (or close to) equilibrium with its surrounding environment. When sampled at high resolution (sub-seasonally), oxygen isotopes can be used to reconstruct the full annual SST range. The estimated SSTs closely match the range of instrumental SSTs measured in the study area, whilst the last deposited (edge) shell-calculated SST can be used to determine the season of animal death. This study shows that well-preserved shells of <em>C. luhuanus</em> can serve as excellent high-resolution palaeotemperature archives for the tropical reef-flat zone. This research underpins the use of this species in future research to determine human-environment interactions and reconstruction of palaeoclimate from archaeological and fossil samples in the Western Pacific Ocean.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112633"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143160296","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":"Role of Oceanic Anoxic Events in regulating the Jurassic–Early Cretaceous taxonomic diversity of Mediterranean brachiopods","authors":"Attila Vörös ,&nbsp;Ottilia Szives","doi":"10.1016/j.palaeo.2025.112788","DOIUrl":"10.1016/j.palaeo.2025.112788","url":null,"abstract":"<div><div>This research investigated the taxonomic diversity of brachiopods during the Jurassic–Early Cretaceous, with a special focus on the Mediterranean. The term Mesozoic Mediterranean brachiopod fauna (MMBF) is introduced here, and its taxonomic novelty is described in detail. Since its establishment in the earliest Jurassic until its disappearance by the late Hauterivian, the deep-water benthic community of the MMBF has been profoundly different from that of any other brachiopod fauna. Compared with the genus and species richness of the rest of the world, the MMBF had special importance in brachiopod history in terms of being an isolated faunal province and evolution center. An analysis of PBDB records via statistical methods revealed that brachiopods – both in the global pool and in the Mediterranean – responded sensitively to changes in the ocean–atmosphere system, and their taxonomic diversity patterns at the genus and species levels also showed significant synchroneity to Oceanic Anoxic Events. These deoxygenation intervals might have played a major role in deep-time brachiopod evolution as one of the most important regulatory forces.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"663 ","pages":"Article 112788"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143312307","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":"Quartz luminescence chronology reveals late Holocene coastal dune development in South China and its correlation with regional sea level fluctuations","authors":"Jianhui Jin ,&nbsp;Junjie Wei ,&nbsp;Zhiyong Ling ,&nbsp;Zhizhong Li ,&nbsp;Feng Jiang ,&nbsp;Chenyang Hou ,&nbsp;Daiyu Xu","doi":"10.1016/j.palaeo.2024.112653","DOIUrl":"10.1016/j.palaeo.2024.112653","url":null,"abstract":"<div><div>The coastal zone has long been the primary area of human activity. Along China's eastern coastline, which stretches for a considerable distance, intermittent deposits of typical coastal aeolian sand can be found along the South China coast. Aeolian sand not only impacts human activities and living spaces in the region but also preserves valuable information about complex environmental changes in the coastal zone. Building upon recent studies on luminescence chronology of coastal aeolian sand in Fujian Province, this study analyzes the temporal and spatial deposition process of regional coastal aeolian sand while considering other climatic and environmental proxy indicators to explore the relationship between periods of coastal aeolian sand activity and regional sea level and climate change. The findings indicate that: 1) significant development of aeolian sediment occurred after the H_II high sea level event. Coastal dune deposition can serve as a record for aeolian sand activity since 3 ka, providing insights into climate change during that period. Deposits from early to Middle Holocene containing records of aeolian sand activity and shoreline changes larger than 3 ka are primarily preserved in local low mountainous and hilly areas or geological boreholes within the coastal zone; 2) geochronological analysis reveals three stages (two active stages and one stable stage) in the deposition process of aeolian sediment since 3 ka: during the first stage, rapid regressive processes led to typical formation of aeolian sediments; in the second stage influenced by regional high sea levels, sedimentation rates were at their lowest with dunes entering a stable phase; finally, during third stage when sea levels approached modern levels, strong East Asian winter monsoon combined with increased coastal population and vegetation damage since the Song Dynasty led to a highly active period of coastal aeolian sand, becoming a major disaster type in South China's coastal areas.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112653"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159406","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":"Astronomical forcing of the paleoclimate and sedimentary noise modeling of sea-level changes in the Late Triassic","authors":"Qian Zhang ,&nbsp;Xiugen Fu ,&nbsp;Shaohua Su ,&nbsp;Shengqiang Zeng","doi":"10.1016/j.palaeo.2024.112638","DOIUrl":"10.1016/j.palaeo.2024.112638","url":null,"abstract":"<div><div>The difficulty of reconstructing sea-level change and the lack of high-resolution geochronology have impeded progress in understanding the relationship between shallow-sea astronomical forcing and lithologic rhythms. Here, we evaluated the impact of astronomical forcing on the lithologic rhythms of the Late Triassic strata in the Qiangtang Basin of the Tibetan Plateau using gamma-ray (GR) from the QZ-16 well to conduct cyclostratigraphic analysis and sedimentary noise modeling. A high-resolution floating astronomical age scale of up to 3.8 Myr was established by tuning the natural gamma data of the Boli La Formation to the stable 405 kyr long eccentricity cycles. This floating astronomical age scale is anchored to the boundary age between the Boli La and Bagong formations (233.16 Ma), thus establishing an anchored absolute astronomical age scale for the studied interval, ranging from 236.98 ± 1.42 to 233.16 ± 1.37 Ma. Additionally, the sedimentary noise modeling of the tuned GR datasets reveals the relative sea-level change during the Boli La Formation's depositional period, which is consistent with the global sea-level change during the same period. In particular, the sea-level variations exhibit the apparent long-term obliquity cycles, which substantially are consistent with the global sea-level and observed obliquity/total power curve, suggesting that the long-term obliquity cycle was the driving force behind the sea-level change and the modulation of water exchanges between the oceans and continents during the Late Triassic greenhouse period, thus validating the aquifer-eustasy hypothesis. These inferred sea-level changes are supported by sequence stratigraphic interpretations. Moreover, the alternation of clastic and carbonate may be controlled by insolation modulation and sea-level changes. This study provides an important research example for exploring the correlation of astronomical forcing with sea-level, paleoclimate, and lithologic rhythmic changes.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112638"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159405","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":"Traditional and clumped isotope oyster sclerochronology: Implications for sub-annual temperature and water chemistry variation in the Western Interior Seaway during the mid-Cretaceous Thermal Maximum","authors":"Jon J. Hoffman ,&nbsp;Sierra V. Petersen ,&nbsp;Matthew M. Jones","doi":"10.1016/j.palaeo.2025.112778","DOIUrl":"10.1016/j.palaeo.2025.112778","url":null,"abstract":"<div><div>Invertebrate macrofossils from the shallow, expansive Cretaceous Western Interior Seaway (WIS) of North America preserve a rich archive of climate and environmental information from a past greenhouse climate interval in their shell chemistry. The use of traditional oxygen isotope paleothermometry on WIS fossils has been thwarted by known but unquantified variations in the oxygen isotopic composition (<em>δ</em>¹⁸O_w) and salinity of seaway waters, interannually and also potentially subannually. Here, we present subannual-resolution clumped isotope (Δ₄₇) sclerochronology records from fossil <em>Exogyra</em> and <em>Pycnodonte</em> specimens (<em>Ostreida</em>) dating to the Cretaceous Thermal Maximum to estimate paleoseasonality in temperature and <em>δ</em>¹⁸O_w in the mid-latitude WIS during this period of peak warmth. We demonstrate that <em>δ</em>¹⁸O_carb -based estimates consistently underestimate the mean annual range in temperature (MART) compared to T_Δ47-based estimates (MART = 2 to 17 °C vs. ≥14 to ≥23 °C) due to co-occurring changes in <em>δ</em>¹⁸O_w. Subannual changes in <em>δ</em>¹⁸O_w are positively correlated with subannual changes in temperature. T_Δ47-based estimates of MART are higher than most mid-latitude sites today. High MART estimates, combined with findings of subannual variations in <em>δ</em>¹⁸O_w may both be the result of seasonal-scale circulation changes in the basin bringing northern vs. southern water masses to the mid-latitude study region. Alternatively, this data may also be explained by seasonal changes in freshwater delivery. Either scenario would likely have been accompanied by sizable salinity fluctuations. These suggestive seasonal water chemistry changes imply niche flexibility for the oysters in this study and may have been a limiting factor on faunal diversity in the seaway for stenohaline organisms.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"664 ","pages":"Article 112778"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403388","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":"Bivalve faunal changes in Xunhua Basin shed light on the Late Miocene uplift, cooling and aridification of NE Tibetan Plateau","authors":"Jiahao Li ,&nbsp;Bowen Song ,&nbsp;Tingting Yu ,&nbsp;Kexin Zhang ,&nbsp;Junliang Ji ,&nbsp;Thomas J. Algeo ,&nbsp;Jingeng Sha ,&nbsp;Sha Li","doi":"10.1016/j.palaeo.2024.112669","DOIUrl":"10.1016/j.palaeo.2024.112669","url":null,"abstract":"<div><div>The Xunhua Basin, a subbasin of the Longzhong Basin in an arid region of the northeastern Tibetan Plateau, hosts a thick succession of Upper Cenozoic fluvial-lacustrine sediments containing climate-sensitive freshwater mollusks, which can provide key insights into the uplift history of the Tibetan Plateau and its relationship to global climate change. In this study, we studied six genera and eleven species of freshwater mussels of the family Unionidae from the Upper Miocene Liushu Formation of the Xunhua Basin. These genera include <em>Unio</em>, <em>Acuticosta</em>, <em>Anodonta</em>, <em>Cristaria, Lanceolaria</em> and <em>Ptychorhynchus</em>. The fossils not only enhance our understanding of biological diversity on the Miocene Tibetan Plateau but also shed light on the biological response to Late Cenozoic orogenic uplift and environmental changes. The Unionidae family is present in modern China mainly in freshwater lakes on the middle and lower reaches of the Yangtze River Basin, i.e., in a humid subtropical monsoonal climate, and it has been extinct in northwestern China (including Qinghai Province) since the Late Miocene. This modern distribution implies that environmental conditions in the Xunhua Basin during the Late Miocene were substantially more humid than at present. Such a sharp contrast in habitat to that of the modern Xunhua Basin implies that a Late Miocene climate shift on the NE Tibetan Plateau occurred after 8.2 Ma, i.e., a climatic drying and cooling trend triggered both by regional tectonic uplift and global climate change, which significantly impacted freshwater ecosystems in the Xunhua Basin.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112669"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159688","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":"Carbon isotope (δ13Ccarb) stratigraphy of the Ordovician of northern Guizhou, South China: Implications for global correlation","authors":"Ya Cui ,&nbsp;Xianyin An ,&nbsp;Yujie Zhang ,&nbsp;Renjie Zhou ,&nbsp;Xin Wang ,&nbsp;Yongjuan Gao ,&nbsp;Yang Wang ,&nbsp;Yuejun Wang","doi":"10.1016/j.palaeo.2024.112637","DOIUrl":"10.1016/j.palaeo.2024.112637","url":null,"abstract":"<div><div>Carbon isotopic chemostratigraphy is essential for reconstructing past carbon cycles, environmental changes and major biogeological events in Earth's history. This study analyzes carbon and oxygen isotopes from the Shiqian section in the Upper Yangtze region, and offers new insights into the carbon cycle and environmental shifts in South China during the Ordovician period. The data highlight five trends that (1) a notable increase in δ¹³C_carb from −1.19 ‰ to 0.98 ‰ at the base of Tunghzu Formation at the Early Tremadocian, (2) a ∼ 2.75 ‰ negative excursion in the Late Tremadocian, (3) a drop in δ¹³C_carb from 0.43 ‰ to −2.33 ‰ at the Late Meitan Formation at the Darriwilian, (4) a positive δ¹³C_carb shift from −2.33 ‰ to 1.18 ‰ at the Shihtzupu Formation during the Late Darriwilian, and (5) a positive excursion from 0.73 ‰ to 2.65 ‰ at the base of the Pagoda Formation during the Early Katian. These variations in carbon isotope align with trends documented in the contemporaneous sequences at both regional and global scales. Our analyses, along with the available data, reveal that the Ordovician δ¹³C_carb shift is coupled with fluctuations in δ¹⁸O, δ²³⁸U, Ce/Ce* and ⁸⁷Sr/⁸⁶Sr. Such a correlation suggests that enhanced organic matter burial/increased marine productivity, climate cooling and oxidation were key factors in promoting biodiversity.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"659 ","pages":"Article 112637"},"PeriodicalIF":2.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143159691","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}