Palaeogeography, Palaeoclimatology, Palaeoecology最新文献

{"title":"The last 20,000 years of climate change in the Iberian Peninsula characterized by the small-mammal assemblages","authors":"Sara García-Morato ,&nbsp;Ángel C. Domínguez-García ,&nbsp;Paloma Sevilla ,&nbsp;César Laplana ,&nbsp;Yolanda Fernández-Jalvo","doi":"10.1016/j.palaeo.2024.112545","DOIUrl":"10.1016/j.palaeo.2024.112545","url":null,"abstract":"<div><div>Climate and environments have undergone significant changes throughout the Earth's history, which are reflected in the faunal record. In that sense, small mammals provide valuable palaeoecological insights due to their close relationship with their associated environments. Our research investigates the dynamics of small mammal communities in the Iberian Peninsula from the Late Pleistocene to the Holocene, comparing regional environmental variations as well as anthropogenic impacts. Our review of the small mammal assemblages from 26 archaeological sites across the Iberian Peninsula revealed a differential response of the small mammal communities between the northern and southern areas. The colder climatic conditions which characterized the Late Pleistocene favoured the presence of mid-European species (e.g., <em>Alexandromys (Oecomicrotus) oeconomus, Chionomys (Chionomys) nivalis</em>) in northern regions until the Mid Holocene, while other taxa today restricted to northern Iberia (e.g., <em>Arvicola amphibius, Microtus gr. (Euarvicola) arvalis, Sorex araneus-coronatus</em>) reached southern regions during the Last Glacial Maximum but disappeared at the beginning of the Holocene period. Palaeoenvironmental reconstructions indicate predominantly open landscapes and colder climates in the Late Pleistocene, with increased forest cover during the Early-Mid Holocene in northern areas. In contrast, the southern regions exhibited more stable environments compared to the northern ones. Our results underscore how the great environmental diversity and interactions between natural and anthropogenic factors affected the composition of Iberian small mammal communities during the last 20,000 years. Most specifically, during the Late Holocene, biogeographical patterns of the small mammals are mostly affected by anthropic activities, with changes in the distribution of some species (<em>Microtus (Iberomys) cabrerae</em>), and the entrance of new ones (synanthropic species).</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112545"},"PeriodicalIF":2.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440916","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":"Intra-tooth isotopic analysis shows seasonal variability in the high-elevation context of Melka Kunture (Upper Awash Valley, Ethiopia) during the Early Pleistocene","authors":"Giuseppe Briatico ,&nbsp;Margherita Mussi ,&nbsp;Rita T. Melis ,&nbsp;Denis Geraads ,&nbsp;Hervé Bocherens","doi":"10.1016/j.palaeo.2024.112555","DOIUrl":"10.1016/j.palaeo.2024.112555","url":null,"abstract":"<div><div>In order to investigate seasonal changes in diet, environment and climate, we analyzed the stable carbon and oxygen isotopic composition of intra-tooth sequential profiles (14 teeth, 282 enamel samples) of Hippopotamidae, Equidae, Bovidae and Suidae from Melka Kunture, Upper Awash Valley, central Ethiopian Highlands (2000–2200 m a.s.l.).</div><div>We found that during the Early Pleistocene, between 1.95 and 1 Ma, most of the analyzed hippos display a seasonally stable C₄ diet, even if the <em>δ</em>¹³C values within hippos show a degree of variability that we interpret as the outcome of feeding on plants that use different C₄ photosynthetic pathways. Several hippo specimens display a seasonal shift from C₄ to mixed C₃-C₄ diets. The sampled equid, bovid and suid specimens recorded both stable C₄ diets and mixed C₃-C₄ feeding with a seasonal progressive increase of <em>δ</em>¹³C values. When affected by seasonal changes, the serially analyzed taxa show different niche partitioning: hippos increase the consumption of C₃ vegetation, whereas equids and suids include more C₄ vegetation in their diets. The intra-individual <em>δ</em>¹⁸O variability in the analyzed taxa is interpreted as the outcome of different water sources, depending on animal habitat, behavior and mobility patterns.</div><div>Our data are placed in controlled stratigraphic and chronological sequences and combined with the outcome of other proxies, allowing us to evaluate the site paleoecology comprehensively. We suggest that the central Ethiopian Highlands, where MK is located, possibly acted as a refugium-like area during the Early and Middle Pleistocene, characterized by a specific type of montane vegetation (DAF) and diverse faunal and hominin species that demonstrated their resilience and adaptability to changing environments and climates.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112555"},"PeriodicalIF":2.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438127","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 sequestration in a typical mountain lake associated with earthquakes, floods, droughts, and human activities in southern Altay during the late Holocene","authors":"Fangming Zhang ,&nbsp;Jiawei Fan ,&nbsp;Hongyan Xu ,&nbsp;Wei Shi ,&nbsp;Xiaotong Wei ,&nbsp;Hanchao Jiang ,&nbsp;Wei Zhang ,&nbsp;Jule Xiao","doi":"10.1016/j.palaeo.2024.112554","DOIUrl":"10.1016/j.palaeo.2024.112554","url":null,"abstract":"<div><div>Lakes, being key regulators of atmospheric carbon dioxide (CO₂), have not yet been intensively explored in the carbon cycle. This study provides an attempt to investigate how carbon sequestration in mountain lakes responds to seismic activities, extreme climate events and human disturbance. The new data of grain-size end members (EMs), TN contents, C/N, concentrations of algal spores, and P and Mn contents, in addition to previously published data of TOC and Ca contents, Zr/Rb, Rb/Sr, and land-pollen assemblages of a well-dated sediment core from Yileimu Lake, depicted a more detailed history of environmental evolution in the region. A great earthquake happened in southern Altay at ∼ 3500 cal yr BP that triggered extensive landslides around the lake, and then frequent floods eroded the catchment between ∼ 3500 and 2300 cal yr BP, subsequently severe drought events occurred within the period of 2300–1000 cal yr BP, finally agricultural and pastoral activities intensified within the last 1000 yrs. Organic carbon accumulation rate (OCAR) in Yileimu Lake was extremely high (an underestimated value of ∼ 370 g m^–2 yr^–1) during the earthquake event, in response to the rapid accumulation of landslide materials. Regional comparison revealed that summer temperature was unexpected to have determined the OCAR during both flood and drought events (average 4.07 and 3.64 g m^–2 yr^–1, respectively), because it dominated the production of land- and aquatic plants. Human activities increased the OCAR prominently (averages 6.26 g m^–2 yr^–1) via changing sediment production and vegetation planting, which decoupled the OCAR from climate factors. These data imply that carbon sequestration in lakes from mountain areas where temperature adversity stress dominated vegetation growth would have the potential to increase under anthropogenic warming. In addition, seismically induced carbon sequestration in lakes from tectonically active regions cannot be ignored.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112554"},"PeriodicalIF":2.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441018","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, temperature, and Indian Summer Monsoon evolution over the past 4400 years revealed by a pollen record from Drigo Co on the southern Qinghai-Tibet Plateau","authors":"Feiya Lv ,&nbsp;Xiaqing Wang ,&nbsp;Fenggui Liu ,&nbsp;Dejun Wan ,&nbsp;Kehan Zhou ,&nbsp;Pengjia Zhang ,&nbsp;Yumei Peng ,&nbsp;Shengrui Zhang","doi":"10.1016/j.palaeo.2024.112556","DOIUrl":"10.1016/j.palaeo.2024.112556","url":null,"abstract":"<div><div>Understanding the changes in temperature and precipitation on the southern Qinghai-Tibet Plateau (QTP), which is influenced by the Indian Summer Monsoon (ISM), is crucial for predicting possible future changes in the regional ecological environment under ongoing climate change. However, due to the lack of well-dated, high-resolution paleoclimate records, the trends of temperature and ISM precipitation on the southern QTP since the mid-Holocene are poorly understood. We present a high-resolution pollen record from Dirgo Co, on the southern QTP, spanning the past 4400 years. The decrease in the pollen ratio of <em>Artemisia</em> to Cyperaceae (A/Cy) indicates a downward shift of altitudinal vegetation belts in the Drigo Co area over the past 4400 years, suggesting falling temperatures; and decreases in tree pollen percentages indicate the gradual weakening of the ISM. Our pollen record also indicates five cold phases with the near-simultaneous weakening of the monsoon, during: 4300–4100 cal yr BP, 3600–3400 cal yr BP, 2800–2600 cal yr BP, 1600–1400 cal yr BP, and 700–100 cal yr BP, and these climate anomalies were also recorded elsewhere on the QTP. We suggest that the changes in temperature and ISM intensity on the southern QTP over the past 4400 years were modulated by changes in summer insolation and solar activity. These changes affected the sea surface temperature (SST) over the tropical Pacific and Indian Ocean regions, and they were linked to a positive phase of the El Niño/Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), which weakened the ISM intensity in the Drigo Co area. Additionally, due to increased evaporation related to high temperatures, combined with intensified grazing activities over the past ∼200 years, the lake level has fallen, and the vegetation cover has decreased. As global temperatures continue to rise, the alpine steppe in the Drigo Co area may increase and the vegetation density may gradually decrease, and at the same time the regional ecological environment may gradually deteriorate.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112556"},"PeriodicalIF":2.6,"publicationDate":"2024-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142445303","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":"Fingerprint of Plio–Quaternary detrital zircon geochronology: Implications for sediment provenances and geomorphological evolution of the Yangtze Delta","authors":"Wei Yue ,&nbsp;Shouye Yang ,&nbsp;Xiyuan Yue ,&nbsp;Baocheng Zhao ,&nbsp;Xiangtong Huang ,&nbsp;Lingmin Zhang ,&nbsp;Yalong Li ,&nbsp;Jing Chen ,&nbsp;Zhongyuan Chen","doi":"10.1016/j.palaeo.2024.112552","DOIUrl":"10.1016/j.palaeo.2024.112552","url":null,"abstract":"<div><div>The Yangtze (Changjiang) Delta serves as a prominent depocenter for siliciclastic sediments from the Tibetan Plateau and Yangtze Craton, providing essential data on sediment source-to-sink dynamics and geomorphological evolution of large river drainage systems. This study presents the detrital zircon geochronology of Plio–Pleistocene sediments in the Yangtze Delta, alongside the data from modern river sediments, to elucidate provenance evolution since the Pliocene. The zircon geochronology reveals a considerable shift in sediment provenance during the Pliocene–Pleistocene transition. The Pliocene sediments exhibit a straightforward and predominant zircon age spectrum characterized by a typical peak age of 100–200 Ma. This spectrum markedly differs from the modern upper–middle Yangtze River sediments but closely resembles those of local rivers in the lower Yangtze River region. This demonstrates that the Pliocene sediments originated from local mountainous rivers, indicating the paleo-Yangtze River channelization prior to the Quaternary. In contrast, the zircon age spectra of Pleistocene sediments in the present-day delta reveal several dominant age groups ranging from 11.9 ± 1 to 3643 ± 30 Ma, similar to those found in present-day upper–middle Yangtze River sediments. This implies that the Pleistocene sediments were mainly derived from the upper–middle Yangtze River, showing a diversity of source rocks with varying geological ages and origins. The presence of the upper Yangtze River provenance signal, characterized by Cenozoic (&lt;65 Ma) zircons, in early Pleistocene strata (ca. 1.6 Ma) of the delta suggests that the paleo-Yangtze River transported Tibet-sourced sediments into the modern delta area no later than that time. These findings indicate the geomorphological evolution of the Yangtze River Delta from an intermontane basin in the Pliocene to an alluvial–fluvial plain during the Quaternary. This geomorphological and geographic evolution, along with changes in sediment source, directly reflect extensive tectonic subsidence in eastern China since the late Cenozoic.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112552"},"PeriodicalIF":2.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438126","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":"Globally synchronous meteorite rain during the Middle Ordovician","authors":"Shengchao Yang ,&nbsp;Junxuan Fan ,&nbsp;Christian M.Ø. Rasmussen ,&nbsp;Xiao-Lei Wang ,&nbsp;Zongyuan Sun ,&nbsp;Yiying Deng","doi":"10.1016/j.palaeo.2024.112550","DOIUrl":"10.1016/j.palaeo.2024.112550","url":null,"abstract":"<div><div>A Middle Ordovician breakup of a L-chondrite asteroid parent body (LCPB) has been suggested to have facilitated both an ice age and a major radiation of marine life. This hypothesis, however, is debated as Baltic data show an offset between the events on Earth and the LCPB-associated meteorite rain. Here, we present the first SIMS U<img>Pb date (465.9 ± 3.3 Ma) from zircons in a bentonite from the Wangjiawan region, South China. We pinpoint the events in space, the LCPB breakup, to have occurred at 466.09 ± 3.3 Ma, and further estimate that the extraordinarily intense micrometeorite rain lasted 2.58 ± 0.27 Myr with an intensity of ∼2.9 × 10⁴ grains/m²/Myr. This suggests that the influx intensity would likely have been too minimal to have had any discernable effect on either climate or biodiversity levels. Our U/Pb age from South China thus implies that the LCPB breakup was a synchronous global event, but was too insignificant in intensity, and further occurred after both the major climatic shift and biological radiation, indicating no relationship between them.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112550"},"PeriodicalIF":2.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440918","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":"Modern reconstructions of mean and seasonal-scale climate from coastal marine gastropods (Turritellidae)","authors":"Serena R. Scholz ,&nbsp;Sierra V. Petersen ,&nbsp;Brendan M. Anderson","doi":"10.1016/j.palaeo.2024.112553","DOIUrl":"10.1016/j.palaeo.2024.112553","url":null,"abstract":"<div><div>Turritellid gastropods are aragonitic marine mollusks that are particularly abundant and widespread in the fossil record. With fast growth rates and a shallow coastal habitat, the oxygen isotopic composition of their shells has the potential to be an excellent recorder of ancient subannual climate variation. To date, tests of the reliability of oxygen isotope paleothermometry in this family of gastropods have been restricted to a few localities. We produce 15 new high-resolution oxygen isotope profiles of modern turritellid shells, and combine these with 28 other published profiles from a range of latitudes and locations in order to investigate generalizable relationships between shell δ¹⁸O_carb and local climate data including temperature, precipitation, salinity, and δ¹⁸O_sw. We find that turritellids accurately record mean SST values using existing temperature-δ¹⁸O_carb relationships, but seasonal ranges in SST are frequently overestimated. Modern climate data from our study sites show correlations that can explain this overestimation through the following proposed mechanism: seasonal increases/decreases in rainfall lead to decreases/increases in local salinity and, by inference, δ¹⁸O_sw, amplifying the seasonal signal in δ¹⁸O_carb. We find that ignoring these seasonal variations in δ¹⁸O_sw can significantly bias the calculation of seasonal temperature ranges from δ¹⁸O_carb profiles derived from turritellids. Similar processes may also affect sclerochronological records from other nearshore, shallow-water marine calcifiers.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112553"},"PeriodicalIF":2.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142440917","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":"Seasonal relative humidity recorded in tree-ring earlywood and latewood δ18O in the West Tianmu Mountains, southeastern China","authors":"Hui Wang ,&nbsp;Yaping Zhang ,&nbsp;Congcong Xiao ,&nbsp;Shiyuan Shi ,&nbsp;Jiarui Xu ,&nbsp;Michael E. Meadows ,&nbsp;Jiangfeng Shi","doi":"10.1016/j.palaeo.2024.112551","DOIUrl":"10.1016/j.palaeo.2024.112551","url":null,"abstract":"<div><div>The West Tianmu Mountains, situated in the southeastern region of China, is profoundly influenced by the East Asian monsoon. Total ring oxygen isotope (δ¹⁸O) has been used previously to reconstruct hydroclimatic signals during the growing season in this region, but high-resolution analyses, i.e., at the intra-annual scale, are scarce. Here, we selected four suitable <em>Pinus taiwanensis</em> Hayata tree cores, measured each ring's α-cellulose δ¹⁸O values in both earlywood and latewood, and established earlywood and latewood δ¹⁸O_cell chronologies from 1951 to 2019, overlapping the period of the observed meteorological data. The mass-weighted mean values of earlywood and latewood δ¹⁸O_cell were calculated to build the total ring δ¹⁸O_cell chronology. The total ring δ¹⁸O_cell chronology is revealed to respond primarily to hydroclimate during the growing season, more specifically relative humidity (RH) during the period May to October. Earlywood δ¹⁸O_cell chronology exhibits the highest correlation with May to June RH, while latewood δ¹⁸O_cell chronology correlates significantly with August to October RH. This observation indicates that the extraction of different seasonal hydroclimatic signals, such as the early or late stages of the growing season, is feasible. Furthermore, we show that tree-ring δ¹⁸O_cell is positively correlated with central and eastern Pacific sea surface temperatures and, accordingly, exhibiting a close connection with El Niño-Southern Oscillation (ENSO). Earlywood δ¹⁸O_cell contains stronger ENSO signals than latewood for two reasons. Firstly, earlywood δ¹⁸O_cell generally retains more precipitation δ¹⁸O signals, and secondly, May to June precipitation δ¹⁸O, which is more contained in earlywood than in latewood δ¹⁸O_cell, has stronger connections with ENSO than other months.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112551"},"PeriodicalIF":2.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441017","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":"Genesis mechanism and potential controlling factors of different types of glauconite in Cambrian strata, northern China","authors":"Dang Zhiying ,&nbsp;Shen Yulin ,&nbsp;Zhu Yulin ,&nbsp;Li Zhuangfu ,&nbsp;Yang Tianyang ,&nbsp;Wen Zuchao ,&nbsp;Jing Yuhong ,&nbsp;Lu Lu","doi":"10.1016/j.palaeo.2024.112547","DOIUrl":"10.1016/j.palaeo.2024.112547","url":null,"abstract":"<div><div>Single-layer glauconites with thicknesses ranging from millimeters to centimeters have been widely developed in the Cambrian tidal flat-shoal environments in the Xuzhou area, northern China. The Cambrian glauconite-bearing sedimentary sequences in this area were combined to reconstruct the glauconite formation and its subsequent occurrence environments. Glauconites were generally formed in tidal flat-lagoon environments with low sedimentation rates and coexisted in oolitic shoals, intertidal flats, and subtidal flats, together with granular fractions formed under different types of strong hydrodynamic conditions. The glauconites occur in granular, micellar, and re-agglomerated granular forms with similar chemical compositions, consisting mainly of SiO₂, FeO, Al₂O₃, and K₂O. The Stage 4–Wuliuan is characterized by a hot climate, many types of glauconite, and large variations in maturity. The limestone, quartz sandstone, and silty mudstone all contain glauconite pellets. The glauconite with felsic material as the substrate has a pseudomorphic replacement genesis. The glauconite with mica as the substrate has a layer lattice theory genesis. The micellar glauconite may have been formed by loss of structural water during maturation of the glauconite pellets, i.e., biogenesis and authigenic precipitation genesis. The Guzhangian–Paibian is characterized by a warm climate, a single glauconite type, high maturity, and stability. The reagglomerated granular glauconite distributed in the dolomitic limestone and dolomite is mostly of grain verdissement origin. The ion contents released by the different substrates were different, and transportation also inhibited the glauconite development, making the degree of glauconization in the Cambrian unstable. The influence of substrate composition on glauconite maturity remains uncertain, but glauconites of stable size (∼100 μm), regular shape, and uniform color generally show higher and more stable levels of glauconitization. Glauconite has a robust temperature tolerance and can develop in environments characterized by weakly oxidizing to weakly reducing conditions, transgression-regression stage of sea level rise and flourishing biological conditions. The accumulation phase of glauconite may indicate a major transition in the Cambrian ecosystem.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112547"},"PeriodicalIF":2.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142441019","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":"Hydrographic restriction conditions in the Middle and Upper Yangtze region during the Early Silurian post-glacial transgression: Constraints from major, trace elemental geochemistry and Mo-TOC relationship","authors":"Chuan Wang,&nbsp;Tian Dong,&nbsp;Zhiliang He,&nbsp;Xiaowen Guo,&nbsp;Sen Liu","doi":"10.1016/j.palaeo.2024.112546","DOIUrl":"10.1016/j.palaeo.2024.112546","url":null,"abstract":"<div><div>Redox-sensitive trace metals have not only been widely used as the proxy for palaeoredox potential due to the strong enrichments under reducing conditions but also provide critical information into water-mass properties, such as the degree of basin restriction. In order to reveal the Early Silurian post-glacial transgression hydrographic restriction conditions throughout the Middle and Upper Yangtze region, trace metal concentrations and organic geochemical data of the lower Longmaxi Formation were analyzed by the Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Leco combustion techniques. We analyzed the hydrographic restriction conditions and redox conditions of different depocenters, including the Southern, Eastern, and Northern Sichuan Basin depocenters and the Western Hubei Region depocenter. The sedimentary Mo-TOC relationship, Mo_EF-U_EF covariation, and upwelling intensity suggest that the Southern, Eastern Sichuan Basin depocenters and the Western Hubei Region depocenter were deep water areas with moderate hydrographic restriction, whereas the restriction conditions of Northern Sichuan Basin depocenter was relatively weak. In addition, due to the combined effect of geographical location, connectivity with the open Qinling Ocean, and estuarine circulation, restriction degrees varied in the same depocenter. The redox proxy (C_org/P) indicated that the lower Longmaxi Formation was deposited in an anoxic water column. There are significant spatial differences in redox conditions in different depocenters and different locations within the same depocenter, which may be controlled by relative sea level rise, hydrographic restriction, and upwelling intensity. Anoxic conditions were more likely to occur in areas where water column was relatively deep and restricted. In addition, the anoxic conditions in the Northern Sichuan Basin depocenter may also associated with the strong upwelling intensity and the behavior of P cycling back to water column, which can promote the primary productivity and further maintain persistent anoxic conditions. The correlation between C_org/P and Mo/TOC indicates that, in relatively weak restriction basin, the trace elements enrichment in sediments was controlled by trace elemental concentrations in seawater. In moderate restriction basin, the trace elements enrichment was mainly controlled by redox conditions. Whereas under more reducing conditions, hydrographic restriction may tend to become the dominant factor. The application of sediment Mo-TOC relationship, Mo_EF-U_EF covariation, and upwelling can provide insights into hydrographic restriction conditions, but the Mo/TOC relationship is limited to anoxic facies, as little trace metal accumulation could also be the consequence of oxic conditions.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"655 ","pages":"Article 112546"},"PeriodicalIF":2.6,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434488","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}