Palaeogeography, Palaeoclimatology, Palaeoecology最新文献

{"title":"Paleomonsoon variability during the past seven centuries: Insights from a northwest Himalayan lake","authors":"Sreya Sengupta ,&nbsp;Anil Kumar Gupta ,&nbsp;Pankaj Kumar ,&nbsp;Prasanta Sanyal ,&nbsp;Manoj Kumar Jaiswal ,&nbsp;Abhayanand Singh Maurya ,&nbsp;Arun Kaushik ,&nbsp;Rahul Pawar ,&nbsp;Rajveer Sharma ,&nbsp;Nitish Kumar","doi":"10.1016/j.palaeo.2025.112911","DOIUrl":"10.1016/j.palaeo.2025.112911","url":null,"abstract":"<div><div>Monsoon rainfall in the northwest (NW) Himalaya is influenced by a complex interplay of various forcing factors, controlling diverse agrarian practices. The NW Himalaya receives the bulk of its rainfall from the Indian summer monsoon (ISM) with a small amount of precipitation originating from the westerlies during winter. To understand ISM variability in the last millennium, a 1 m long core was raised from Tikkar Taal Lake in the Panchkula district of Haryana, India and examined for multiple proxies (grain size, major and trace element ratios, stable isotope (δ¹³C_org) and Total Organic Carbon (TOC Wt). The statistical analyses, including End Member Modelling (EMM), correlation matrix, spectral analysis, Wavelet Transform Coherence (WTC) Analysis along with Continuous Wavelet Transform (CWT) analysis reveal significant changes in the Little Ice Age (LIA) and Current Warm Period (CWP). Accelerator Mass Spectrometry (AMS) ¹⁴C dates of three bulk sediment and two gastropod samples give an age range of ∼700 years. Pacific Decadal Oscillation (PDO) along with El Niño -Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO) are the forcing factors for changes in precipitation. Two climatically significant intervals are identified, LIA (∼1296–1850 CE) with a moderately wet and humid phase from ∼1296 to 1500 CE, followed by a moderately dry phase from ∼1500 to 1850 CE overlapped by the Maunder Minimum (∼1645–1710 CE). The CWP is characterized by humid conditions (1850 CE onwards) coinciding with human-induced changes in the environment. The spectral analysis shows NAO and PDO like cyclicities of 15, 16, 18,19,22 and 28 yrs.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"668 ","pages":"Article 112911"},"PeriodicalIF":2.6,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684726","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":"Linkage between global CO2 concentration and Indian summer monsoon between 309 and 260 kyr BP","authors":"Som Dutt ,&nbsp;Anil K. Gupta ,&nbsp;Jooly Jaiswal ,&nbsp;Hai Cheng ,&nbsp;Priyantan Gupta","doi":"10.1016/j.palaeo.2025.112906","DOIUrl":"10.1016/j.palaeo.2025.112906","url":null,"abstract":"<div><div>A speleothem record of oxygen isotope ratios δ¹⁸O) changes from the Bhiar Dhar cave, Uttarakhand suggests sub-millennium scale variability in Indian summer monsoon (ISM) conditions in the northwestern Himalaya during late marine isotope stage (MIS)-9 and early MIS-8. The results indicate the weakening ISM conditions between 309 and 292 kyr BP and from 286 to 264 kyr BP, and strong ISM from 291 to 287 kyr BP. An abrupt surge in ISM-linked precipitation is observed at ∼287 kyr BP, following which the ISM remained weakened. The oxygen isotope ratio suggests a weak ISM with moderate variations from ∼286 to 264 kyr BP when the monsoon was moderately strengthened. The orbital scale changes in the ISM rainfall from 309 to 260 kyr BP in the study area appear to have been driven by the global ice cover and atmospheric CO₂ concentration superimposed by the northern hemisphere solar insolation.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"668 ","pages":"Article 112906"},"PeriodicalIF":2.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684727","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":"New aspects of the asymmetry of the Great American Biotic Interchange based on an analysis of the spatial and temporal structure of immigrant taxa at local scale","authors":"Luan Moldan Motta,&nbsp;Tiago Bosisio Quental","doi":"10.1016/j.palaeo.2025.112905","DOIUrl":"10.1016/j.palaeo.2025.112905","url":null,"abstract":"<div><div>The Great American Biotic Interchange (GABI) happened after the connection between North and South America was established, forming the Isthmus of Panama. The GABI comprised a well documented pattern characterised by an asymmetrical movement of mammalian migrants, with a higher proportion of North American taxa being found in South America than vice versa. Using mammal fossil occurrences from The Paleobiology Database (PBDB) and Generalized Linear Mixed Models, we tested if the proportion of immigrants in local assemblages presents a spatial structure with respect to the distance from the point of entrance to the new continent. We focused on two Pleistocene intervals, to evaluate if such spatial structures varied with time. We show that during early stages of the Pleistocene there was a strong negative relationship between the proportion of immigrants and distance to the point of continental connection in both North and South Americas. During the later stages of the Pleistocene a strong negative relationship was still recovered in North America; however in South America this relationship is weak, characterizing a new type of asymmetry between the continents. We conducted sensitivity analyses related to fossil dating uncertainty, the spatial definition of local assemblages and data subsetting. Our results are qualitatively robust to all sources of uncertainty. We contrast our spatially explicit results to the classical hypotheses proposed to explain the asymmetry in the proportion of immigrants at the regional scale. We advocate that the time for full expansion of immigrant ranges is a relevant aspect in structuring the spatial pattern of immigrants at the local scale but that interspecific interactions, climate and the difference between pools of temperate and tropical species might also be relevant and more explicitly incorporated in future studies of GABI's results at local scale.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"668 ","pages":"Article 112905"},"PeriodicalIF":2.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143684725","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":"Reconciling redox proxy contradiction with active FeMn shuttle in the Cryogenian Nanhua Basin of South China","authors":"Meng Cheng (程猛) ,&nbsp;Zihu Zhang ,&nbsp;Jun Hu ,&nbsp;Haiyang Wang ,&nbsp;Mengchun Cao ,&nbsp;Chao Li","doi":"10.1016/j.palaeo.2025.112899","DOIUrl":"10.1016/j.palaeo.2025.112899","url":null,"abstract":"<div><div>The Cryogenian Period is one of Earth's most critical time intervals for biological innovation and manganese (Mn) accumulation. The formation of the Mn ores in the Cryogenian Nanhua Basin (South China) has been attributed to early diagenesis with transient oceanic oxygenation evidenced by low C_org/P and high Ce/Ce*, but reconstruction of the ocean redox with Fe speciation revealed persistently anoxic water conditions in the basin. To address this disagreement, we conducted new δ³⁴S measurements of pyrite and carbonate-associated sulfate (CAS), together with bulk major and trace element compositions in three drill cores of the Datangpo Formation collected from the Nanhua Basin. The δ³⁴S values of both CAS and pyrite were significantly higher than the estimated seawater sulfate in the contemporary open ocean, likely reflecting the hydrographic restriction of the Nanhua Basin and a small sulfate reservoir size in the open ocean. Additionally, the superheavy δ³⁴S of pyrite is higher than its paired CAS, which can be best explained by partial oxidation of H₂S during the inflow of open ocean seawater, or the emission of volatile organosulfur, both indicating the bottom water was not fully oxygenated. Partial oxidation of H₂S might be caused by the episodic inflow of open ocean seawater, which would result in fluctuations in the depth of the chemocline, enhancing the activity of the Fe<img>Mn shuttle. The operation of Fe<img>Mn shuttle might adsorb P and Ce in shallow oxic waters, transport them to the deeper anoxic waters, and release them back into the water column. Therefore, we propose that the low C_org/P and positive Ce/Ce* in the Mn‑carbonates may indicate a stronger Fe<img>Mn shuttle effect rather than oxic water conditions. The contradictory results of different redox proxies in the Cryogenian Nanhua Basin thus can be reconciled with widespread anoxia in the open ocean, strong basin restriction, and episodic seawater inflow that caused enhanced Fe<img>Mn shuttle.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"667 ","pages":"Article 112899"},"PeriodicalIF":2.6,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143682087","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":"Marine redox evolution and organic matter accumulation in the end Guadalupian in NE Sichuan, South China","authors":"Xiaotong Ge ,&nbsp;Baojian Shen ,&nbsp;Daizhao Chen ,&nbsp;Yali Liu ,&nbsp;Ziwen Jiang ,&nbsp;Mu Liu ,&nbsp;Xun Ge","doi":"10.1016/j.palaeo.2025.112901","DOIUrl":"10.1016/j.palaeo.2025.112901","url":null,"abstract":"<div><div>The Guadalupian-Lopingian (G-L) transition represents a pivotal interval, during which changes in oceanic redox conditions have been proposed to correlate with the end-Guadalupian mass extinction. However, the detailed spatial and temporal variations in marine redox states are still not well-defined. To explore the concurrent oceanic shifts and the factors controlling organic matter accumulation, we investigate an organic-rich succession from the G-L boundary located in an intrashelf basin in the northeastern Sichuan Basin, Southwest China by means of multiple geochemical indicators, including organic carbon isotope, total organic carbon contents, iron speciation contents, mercury contents and major and trace elements contents. Our results delineate four distinct intervals (I-IV) of redox conditions based on Fe-Mo-U-V data, showing a sequence from suboxic to ferruginous, followed by euxinic, and returning to suboxic conditions. The euxinic phase appears to have been driven by a highly restricted basin environment combined with frequent volcanic episodes. Additionally, the primary productivity peaked in the Interval II₂, which may have been a key factor in the organic matter accumulation. Comparative analysis with studies from other regions indicates that the Paleo-Tethys was more anoxic and exhibited greater stagnation than the Panthalassa during the end-Guadalupian, with the severity of anoxia during the Permian-Triassic transition surpassing that of the G-L transition. Overall, the significant marine anoxia was confined to moderate depths, with varying onset times across different areas, and was notably absent in the pelagic basins. This pattern implies that anoxia might not have been the primary cause of the mass extinction event.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"667 ","pages":"Article 112901"},"PeriodicalIF":2.6,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643944","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":"Oceanic redox condition and the evolution of Ediacaran life: Evidence from nitrogen isotopes and biogenic silica in the Yangtze Block, South China","authors":"Zaiyun Wang ,&nbsp;Hansheng Cao ,&nbsp;Fajin Chen ,&nbsp;Kai Wei ,&nbsp;Chuang Bao ,&nbsp;Qinghua Hou ,&nbsp;Chunqing Chen ,&nbsp;Hanli Huang ,&nbsp;Qiuping Chen","doi":"10.1016/j.palaeo.2025.112903","DOIUrl":"10.1016/j.palaeo.2025.112903","url":null,"abstract":"<div><div>The late Ediacaran period witnessed the largest global carbon cycle disturbance in geological history, known as the “Shuram Excursion”, coinciding with the emergence of early complex multicellular life. While the rise in atmospheric and oceanic oxygen is seen as a major catalyst for this evolutionary leap, the link between oxygenation and Ediacaran diversification remains contested. To investigate this, we reported nitrogen, carbonate, and organic carbon isotopes, as well as biogenic silica (BSi) content from a drill core in the Yangtze Platform, South China. During the lower Shuram excursion, δ¹⁵N decreased from 5.9 ‰ to 2.9 ‰, suggesting a shrinking nitrate pool in the euphotic zone associated with intensified denitrification due to the expansion of the anoxic zone. During the middle Shuram excursion, a significant decline in δ¹³C_carb was accompanied by a rapid increase in δ¹⁵N (up to 5.8 ‰), which likely reflects a transitional redox state characterized by moderate denitrification in the water column, enriching the remaining nitrate in the photic zone with ¹⁵N. The subsequent decline in δ¹⁵N signatures likely reflects reduced water-column denitrification, driven by further ocean oxygenation and the deepening of the chemocline. The concurrent positive excursions in δ¹⁵N and negative δ¹³C_carb correspond to the peak in BSi contents, suggesting that the rise in seawater O₂ levels and the increase in surface nitrate concentrations provided a favorable environment for siliceous organisms. The geochemical signatures observed correspond with the diversification of ecologically important animal groups, emphasizing the accelerated evolution of the Avalon biota in oxygen and nitrate-enriched environments.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"667 ","pages":"Article 112903"},"PeriodicalIF":2.6,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643943","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":"Neoproterozoic rift-related mafic and felsic rocks from the Yangtze Block, South China: Insights into petrogenesis and tectonic evolution","authors":"Jibiao Zhang ,&nbsp;Yanxue Liu ,&nbsp;Heng Zhang ,&nbsp;Chenglong Shi ,&nbsp;Peiwen Liu","doi":"10.1016/j.palaeo.2025.112904","DOIUrl":"10.1016/j.palaeo.2025.112904","url":null,"abstract":"<div><div>Neoproterozoic rift-related magmatism along the margins of the Yangtze Block presents a valuable opportunity to study the tectonic evolution of South China and the geodynamic processes resulting from the breakup of Rodinia. In this paper, we report Neoproterozoic rhyolites, diabases, and granites from the Kangdian and Nanhua Rift basins along the western and southeastern margins of the Yangtze Block, respectively. The Suxiong (ca. 819–824 Ma) and Yejia (ca. 800–804 Ma) rhyolites exhibit high Na₂O + K₂O (7.07–8.67 wt%) and Zr + Nb + Ce + Y (355–930 ppm) contents, zircon saturation temperatures (821–920 °C), and 10,000 × Ga/Al ratios (2.28–4.28), indicating an affinity with A-type granites. These rhyolites have depleted Nd<img>Hf isotopic compositions (ε_Hf(t) = +1.8 to +5.6 and ε_Nd(t) = +3.5 to +4.9, respectively) and are characterized by low Sr/Y (0.14–1.42) and (La/Yb)_N (3.98–9.1) ratios, Mg^# (8–35) values, and high Fe/(Fe + Mg) (0.76–0.96) ratios, suggesting that they were generated primarily by the partial melting of quartzofeldspathic crustal rocks under low-pressure, high-temperature conditions. The ca. 812 Ma Dengxiangying diabases are of the calc-alkaline series, showing enrichments in LILEs and LREEs and depletions in HFSEs. Isotoptic data (ε_Hf(t) = +6.6 to +10.1, ε_Nd(t) = +3.4 to +5.8) suggest that they were derived from the partial melting of subduction-modified lithospheric mantle. The ca. 810 Ma Yifeng granites display a weakly peraluminous character, with low zircon saturation temperatures (752–806 °C), and 10,000 × Ga/Al (2.0–2.6) and Zr + Nb + Ce + Y (155–340 ppm) values, similar to those of I-type granitoids. These granites have depleted whole-rock Nd (+1.5 to +2.6) and zircon Hf (+4.0 to +7.2) isotopic compositions, indicating derivation from the remelting of Mesoproterozoic mafic crustal materials. By integrating the petrogenesis of these Neoproterozoic rift-related rocks, we consider that the Kangdian Rift was a back-arc basin produced in response to the long-term slab subduction beneath the western Yangtze Block, whereas the Nanhua Rift was a continental rift basin produced in response to the upwelling of asthenospheric mantle.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"668 ","pages":"Article 112904"},"PeriodicalIF":2.6,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685273","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":"Climate and lake ecosystem evolution over the last millennium on the north-eastern Tibetan Plateau: Insights from stable isotope records of gastropod shells in Xing Co","authors":"Yunqing Li ,&nbsp;Wanyi Zhang ,&nbsp;Siyao Liu ,&nbsp;Yanrong Zhang ,&nbsp;Xianyong Cao ,&nbsp;Fang Tian","doi":"10.1016/j.palaeo.2025.112896","DOIUrl":"10.1016/j.palaeo.2025.112896","url":null,"abstract":"<div><div>The evolution of alpine lake ecosystems on the north-eastern Tibetan Plateau (NETP) over the last millennium has been affected by climate change and human activity. This study reconstructs the palaeoclimate and lake productivity of Xing Co using carbon and oxygen isotopes from aquatic gastropod shells (<em>δ</em>¹³C_shell and <em>δ</em>¹⁸O_shell), grain-size, total organic carbon (TOC), total nitrogen (TN), and the TOC/TN (C/N) ratio. The highest lake productivity – during the Medieval Warm Period (MWP) – is likely linked to enhanced photosynthesis of aquatic plants and increased biomass within the lake. This increase was driven by warm, humid climate conditions, indicated by higher <em>δ</em>¹³C_shell values, lower <em>δ</em>¹⁸O_shell values, and increased coarse-grain content. In contrast, the significant decline in lake productivity during the Little Ice Age (LIA) resulted from deterioration of trophic status and restricted aquatic plant growth under colder, drier climate conditions. However, the decrease in lake productivity since 1950 CE, amid global warming, may be linked to increased soil erosion and sedimentation rate from intensified human activity and land-use changes. The combined effects of climatic shifts and human disturbances highlight the need for ongoing monitoring of lake ecosystems to understand their resilience and response to future environmental changes.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"667 ","pages":"Article 112896"},"PeriodicalIF":2.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643941","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":"Precipitation reconstruction for the western Chinese Loess Plateau since 1598 CE reveals recent wetting signals","authors":"Yue Li ,&nbsp;Feng Chen ,&nbsp;Xiaoen Zhao ,&nbsp;Weipeng Yue ,&nbsp;Mao Hu ,&nbsp;Junqiang Niu ,&nbsp;Tiyuan Hou ,&nbsp;Yang Xu ,&nbsp;Hechuan Wang ,&nbsp;Shijie Wang ,&nbsp;Honghua Cao ,&nbsp;Youping Chen ,&nbsp;Heli Zhang ,&nbsp;Max C.A. Torbenson","doi":"10.1016/j.palaeo.2025.112898","DOIUrl":"10.1016/j.palaeo.2025.112898","url":null,"abstract":"<div><div>Global warming has emerged as a significant environmental challenge for humanity, particularly in climate-sensitive regions such as the Chinese Loess Plateau (CLP). Climate changes in this region are thought to have led to an increase in extreme weather events, adversely affecting ecosystems and agricultural development. This study uses spruce tree-ring samples to reconstruct precipitation data for the western CLP (WCLP) since 1598 CE. The resulting record accounts for 49 % of the variation in instrumental precipitation from July of the previous year to June of the current year. Through this reconstruction, we document occurrences of extreme drought and wet events over the past 426 years, record significant historical drought events in WCLP, reveal climatic driving mechanisms on different timescales, and analyze recent trends of increasing precipitation. This study contributes to a deeper understanding of the climatic history of the WCLP and provides scientific foundations for future climate predictions and regional sustainable development.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"668 ","pages":"Article 112898"},"PeriodicalIF":2.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143685359","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":"Meridional shifts of Brazil-Malvinas Confluence since the Last Glacial Maximum","authors":"Fang Gu ,&nbsp;Karin A.F. Zonneveld ,&nbsp;Hermann Behling","doi":"10.1016/j.palaeo.2025.112897","DOIUrl":"10.1016/j.palaeo.2025.112897","url":null,"abstract":"<div><div>The Brazil-Malvinas Confluence (BMC) is a highly dynamic convergence of surface currents in the southwestern South Atlantic, where the warm Brazil Current (BC) from the tropical Atlantic meets the cold Malvinas Current (MC) that originates from the northern branch of the Antarctic Circumpolar Current. Meridional shifts of the BMC play an important role in controlling the heat transfer from the tropical Atlantic to the higher latitudes of the South Atlantic. In this study, the marine core GeoB13861–1 is analyzed for pollen, spores, freshwater algae, and organic-walled dinoflagellate cysts (dinocysts) to reconstruct marine and terrestrial paleoenvironmental changes in southeastern South America since the Last Glacial Maximum (LGM). The results indicate that during LGM, the BMC was at its northernmost location due to the strong influence of the MC. During that period, exposed coastal areas of Argentina were dominated by salt marshes shaped by low global sea level. From ∼18 to 15 cal kyr BP, the BMC migrated southward, contributing to more humid conditions on the adjacent continent. As sea level rose, former salt marshes along the coast were gradually flooded. The increased presence of <em>Nothofagus</em> and <em>Podocarpus</em> pollen in the marine record suggests a slight expansion of Andean forests during the Late Glacial, indicating the adjacent continental regions shifted to wetter conditions. Notably, our study confirms that the signals of abrupt climate events, such as Heinrich Stadial 1 (HS1) and Younger Dryas (YD), are well-preserved in the marine sediment records. Our new findings provide clear evidence of the bi-polar sea saw effect during HS1, marked by abrupt ocean warming in the South Atlantic.</div></div>","PeriodicalId":19928,"journal":{"name":"Palaeogeography, Palaeoclimatology, Palaeoecology","volume":"667 ","pages":"Article 112897"},"PeriodicalIF":2.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643945","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}