Global and Planetary Change最新文献

{"title":"Tracing the Changjiang-derived sediments along the southeast coast of China during the Holocene","authors":"Yalong Li ,&nbsp;Xin Shan ,&nbsp;Xiangtong Huang ,&nbsp;Zhanghua Wang ,&nbsp;Jianhua Gao ,&nbsp;Ping Yin ,&nbsp;Quanhong Zhao ,&nbsp;Juan Xu ,&nbsp;Zhen Song ,&nbsp;Shouye Yang","doi":"10.1016/j.gloplacha.2025.104770","DOIUrl":"10.1016/j.gloplacha.2025.104770","url":null,"abstract":"<div><div>Coastal processes, including riverine inputs, alongshore currents, tidal currents, and estuarine circulation, are crucial in shaping the Earth's landscape and regulating land-ocean material cycling. The Changjiang (Yangtze River), the largest river in Asia, has greatly influenced coastal sedimentation and environmental evolution in the East China Sea during the Holocene. However, its interactions with smaller mountainous rivers and their estuaries in southeastern China, as well as the impact of post-glacial sea-level rise on sediment source-to-sink dynamics in this region, remain poorly constrained. Here, we present a comprehensive analysis of the sedimentary characteristics, elemental composition, and Sr<img>Nd isotopic ratios of Core MLX-S obtained from the Mulanxi River estuary. By comparing these findings with literature data from the Changjiang and other coastal estuaries in SE China, we provide new insights into the source-to-sink dynamics in this region. Our results indicate that the postglacial maximum flooding event occurred at ∼4.8 kyr BP in the southern Taiwan Strait and at ∼7.0 kyr BP in the northern Taiwan Strait. The terrigenous sediment mixing between the Changjiang and coastal mountainous rivers can be traced back to the early Holocene, coinciding with the postglacial sea levels rise. As the depositional environment shifted from low-stand fluvial to inner shelf settings, sediment provenances also changed from the dominance of local source (<em>e.g.,</em> Mulanxi) to a mixture of sediments from the Changjiang and local rivers. The average proportion of Changjiang-sourced sediments in Core MLX-S was about 14.2 % during early Holocene (before 9.5 kyr BP), 25.0 % during the early-middle Holocene accompanied by rising sea level (9.5–7.7 kyr BP), 38.5 % during high sea-level period (7.7–0.3 kyr BP), and 29.9 % during the late Holocene with present sea level (after 0.3 kyr BP). These findings suggest that the initial influence of Changjiang sediments on the estuaries of the southeastern coastal rivers occurred prior to the formation of a large-scale mud belt on the inner shelf at ∼8.0 kyr BP. This study underscores the sensitivity of coastal sediment routing to sea-level and climate forcings, demonstrating how large river systems interact with regional smaller rivers to shape marginal marine stratigraphy.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104770"},"PeriodicalIF":4.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A half-century drying in Gobi Oasis, possible role of ENSO and warming/moistening of Northwest China","authors":"Qiang Li ,&nbsp;Yifan Wu ,&nbsp;Xiangyu Duan ,&nbsp;Yu Liu ,&nbsp;Changfeng Sun ,&nbsp;Huiming Song ,&nbsp;Qiufang Cai ,&nbsp;Meng Ren ,&nbsp;Jiachuan Wang ,&nbsp;Zichun Jia ,&nbsp;Hai Cheng","doi":"10.1016/j.gloplacha.2025.104769","DOIUrl":"10.1016/j.gloplacha.2025.104769","url":null,"abstract":"<div><div>To investigate the historical wet/dry fluctuations in Gobi Oasis and its driving mechanism under the background of global warming, a climatological study of tree-ring stable oxygen isotope (δ¹⁸O) was carried out in the Gobi Oasis in northwest China. Based on the tree-ring δ¹⁸O sequence of <em>Populus euphratica</em>, the 124-year (1886–2009) June–August relative humidity history of the oasis was reconstructed, explaining 49.2 % of the total variance of the meteorological observation during 1960–2009. The reconstructed sequence captured the changing characteristics of the relative humidity in the oasis in summer and showed that the wet years in the past 124 years mainly occurred before 1950s, while the relative humidity showed a continuous downward trend after 1950s. The spatial correlation shows that the reconstructed summer relative humidity has good spatial representation and can reflect the large-scale relative humidity variations in Northwestern China from June to August, and is consistent with other paleoclimate reconstructions in adjacent areas. The comparison found that the reconstructed sequence was significantly correlated with the dry-wet indices in the westerlies region at both high and low frequencies, and was significantly correlated with the reconstructions in the monsoon region at low frequency, which imply that the relative humidity in the oasis in summer might be affected by both the westerlies and the East Asian summer monsoon. In addition, we found that the changes in summer relative humidity in the oasis were related to large-scale air-sea interactions. The El Niño-Southern Oscillation (ENSO) in the central Pacific was the main influencing factor.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104769"},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mid-Piacenzian and future changes in South Asian precipitation under global warming","authors":"Xinquan Zhou,&nbsp;Chuanlian Liu","doi":"10.1016/j.gloplacha.2025.104760","DOIUrl":"10.1016/j.gloplacha.2025.104760","url":null,"abstract":"<div><div>This study examines the response of South Asian precipitation to global warming during the mid-Piacenzian and in the near future, using modeling data. Compared to the preindustrial period, both the mid-Piacenzian simulations from the Pliocene Model Intercomparison Project Phase 2 and the future projections under the Shared Socioeconomic Pathways 5–8.5 consistently indicate a wetter climate over South Asia, characterized by higher annual net precipitation. Concurrently, simulations show strengthened summer southeasterly winds over the Arabian Sea. The simulated climate anomalies under the mid-Piacenzian conditions align with the paleoclimatic evidence derived from geological records. Based on the validity of the simulated results in the past, together with the similarity to the future projections, it can be inferred that South Asia will continue to experience a wetter climate driven by increasing anthropogenic greenhouse gas emissions. Further analysis reveals that the wetter climate is primarily driven by increased net precipitation during summer and autumn. A moisture budget analysis indicates that the summer wetting over the Indian Peninsula and the Bay of Bengal is caused by thermodynamic mechanisms, which can be attributed to higher atmospheric humidity of the Intertropical Convergence Zone. In contrast, the autumn wetting over the same region is driven by dynamic processes, linked to enhanced cross-equator moisture transport under a positive Indian Ocean Dipole mean state. Additionally, the orographic precipitation is enhanced in the Himalayas and the Western Ghats during both summer and autumn. A key difference between the two warming scenarios is that the wetting is stronger under mid-Piacenzian warming, despite greenhouse gas concentrations being significantly higher in the future scenario. This discrepancy is suggested to be related to the offsetting influence of an El Niño-like mean state, which suppresses South Asian precipitation in the future scenario.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104760"},"PeriodicalIF":4.0,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 human-induced variability in Holocene Lower Meuse deposition (the Netherlands) identified from the meta-analysis of radiometric data","authors":"W.H.J. Toonen ,&nbsp;H.A.G. Woolderink ,&nbsp;T. Dorrestein ,&nbsp;M. van Noord ,&nbsp;H.J. Pierik ,&nbsp;P. Bakker ,&nbsp;C. Kasse","doi":"10.1016/j.gloplacha.2025.104767","DOIUrl":"10.1016/j.gloplacha.2025.104767","url":null,"abstract":"<div><div>The meta-analysis of riverine deposition from the Holocene provides critical knowledge on the direction and amplitude of riverine responses to climatic and human perturbations and can help to understand the severity and pacing of future changes. For the Meuse River valley in the Netherlands, a dataset of 340 radiometric dates was compiled, on which a cumulative probability density analysis was carried out to characterize the phasing in clastic and organic deposition throughout the Holocene. The results were compared with established timelines for the geomorphological and cultural changes in the valley and hinterland, and hydroclimatic records in the region and wider North Atlantic climate zone. Wavelet analysis was used to identify persistent periodicities, in an attempt to identify long-term hydroclimatic drivers of the Meuse flooding regime.</div><div>The CPDF of clastic deposition reveals limited deposition during the Early Holocene, which we link to the entrenched river setting of that time. Since c. 6 ka BP, the increase in clastic deposition closely followed the trajectory of human impact on land cover. Increased input of clastic material from upland regions led to channel aggradation, which stimulated the formation of floodplain deposits. In the last millennia clastic input increasingly became a limiting factor for the formation of organic deposits, as indicated by their strongly anti-phased correlation.</div><div>Increasing human impact during the Late Holocene seems to have created a supercharged setting where particularly during cold climate episodes the flooding regime intensified and sediment fluxes increased. Such hydroclimatic variability manifests as phasing that is superimposed on the general increase in clastic deposition owed to human impact. Although there seems to be a general correspondence between phases of clastic deposition and main drivers of the North Atlantic climate, such as variability in solar activity and the timing of volcanic eruptions, no specific systematic correlations could be established based on CPDF data. Phases of enhanced organics accumulation during the Early Holocene (anti-)correlate significantly with North Atlantic drift-ice occurrence, suggesting a hydroclimatic link between both processes. The presence of multi-centennial-scale periodicities in both organic and clastic deposition during the last four millennia further suggests a persistent climatic driver imprinting on the build-up of the fluvial archive of the Meuse valley.</div><div>It is argued that CPDFs are a useful tool to understand hydrological regime changes, particularly to identify phases and episodes of anomalous flooding in relation to the relative importance of climatic and anthropogenic forcings, and the geomorphic modulation of such signals. Such data could be considered as important baseline information for potential future flood regime changes.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104767"},"PeriodicalIF":4.0,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143465070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"The effects of mineralogy and early diagenesis on the Cenozoic carbonate Ca and Mg isotopic records from the South China Sea","authors":"Ying Li ,&nbsp;Xiangdong Wang ,&nbsp;Wen Yan ,&nbsp;Guangyi Wei ,&nbsp;Yongjie Hu ,&nbsp;Feifei Zhang ,&nbsp;Shuzhong Shen","doi":"10.1016/j.gloplacha.2025.104757","DOIUrl":"10.1016/j.gloplacha.2025.104757","url":null,"abstract":"<div><div>The δ^44/40Ca and δ²⁶Mg values of marine carbonate are widely used to reconstruct paleo-seawater chemistry. However, post-depositional diagenesis often alters the geochemical signatures, leading to biased interpretations of the seawater archives. Here, we present multi-proxy (C-O-Mg-Ca) isotopic data from late Cenozoic carbonates of the NK-1 core in the South China Sea to evaluate the extent of meteoric and marine diagenetic effects on Ca and Mg isotope compositions. The core-top unconsolidated carbonate sediments (0–20 m), composed of aragonite and high-Mg calcite, yield an average δ^44/40Ca value of 0.84 ‰ (NIST SRM-915a) and δ²⁶Mg value of −3.07 ‰ (DSM-3). Within the meteoric zones (20–120, 443–503, 539–670 m), δ^44/40Ca and δ²⁶Mg values in limestone range from 0.57 ‰ to 1.46 ‰ and − 5.02 ‰ to −2.98 ‰, respectively, showing positive correlations with δ¹³C and δ¹⁸O values. The numerical early diagenetic modelling suggests that δ^44/40Ca and δ²⁶Mg values of limestone decrease under freshwater diagenesis, mainly controlled by the mixing ratios between freshwater and seawater. In contrast, limestone within the marine diagenetic zone (670–700 m) exhibits uniformly high δ^44/40Ca (∼1.48 ‰) and δ²⁶Mg (∼ − 4.08 ‰) values, coupled with positive δ¹³C and δ¹⁸O values, indicating seawater-buffered diagenetic conditions. For dolomite, the high δ^44/40Ca (1.39 ± 0.15 ‰) and consistent δ²⁶Mg (−2.85 ± 0.12 ‰) values suggest the dolomitization occurred under fluid-buffered conditions. The reconstructed late Cenozoic seawater calcium and magnesium isotopic compositions by the NK-1 core dolomite are consistent with the globally published data from other coeval dolomites and various proxies (e.g., carbonate ooze, foraminifera, barite). This highlights the potential of penecontemporaneous dolomite as a reliable recorder of paleo-seawater Ca and Mg isotopic compositions.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104757"},"PeriodicalIF":4.0,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptation and challenges for giant clam species under marine heatwaves","authors":"Jun Geng ,&nbsp;Hong Yan ,&nbsp;Chengcheng Liu ,&nbsp;Nanyu Zhao ,&nbsp;Shan Liu ,&nbsp;Tao Han ,&nbsp;John Dodson ,&nbsp;Hanfeng Wen","doi":"10.1016/j.gloplacha.2025.104746","DOIUrl":"10.1016/j.gloplacha.2025.104746","url":null,"abstract":"<div><div>Amid ocean warming, giant clams face serious threats, yet our understanding of their adaptation to marine heatwaves is limited compared to corals. In the South China Sea, a 9-year record of <em>Tridacna gigas</em> surviving recurrent heatwaves provides valuable insights. Our results indicate that the daily growth bands in <em>T. gigas</em> shell effectively track their growth responses to heatwaves. The <em>T. gigas</em> shell exhibits abnormal growth bands under mild to moderate cumulative heat stress caused by heatwaves but recovers as temperatures return to normal. However, following the severe cumulative heat stress in 1998, shell growth took 2.5 years to gradually return to pre-heat stress levels, indicating a significant negative impact. Unexpectedly, <em>T. gigas</em> has developed some degree of heat tolerance with repeated exposure to heatwaves. However, its ability to withstand heat stress increases non-linearly, and recovery slows significantly after exposure to severe heat stress. This raises concerns about its ability to adapt to future more frequent marine heatwaves.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104746"},"PeriodicalIF":4.0,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dust emissions in the arid Asian interior and abrupt changes in midlatitude atmospheric circulation during the glacial-Holocene transition","authors":"Peixian Shu ,&nbsp;Dongfeng Niu ,&nbsp;Yougui Song ,&nbsp;Yuejun Si ,&nbsp;Shugang Kang ,&nbsp;Baosheng Li ,&nbsp;Weijian Zhou ,&nbsp;Zhisheng An","doi":"10.1016/j.gloplacha.2025.104758","DOIUrl":"10.1016/j.gloplacha.2025.104758","url":null,"abstract":"<div><div>Loess deposits from the Kunlun Mountains provide high-resolution eolian dust archives that allow us to understand past dust emission patterns in the Asian interior, and associated abrupt atmospheric circulation changes during the glacial-Holocene transition. Coarse-grained particles from this area (site AQ16) offer evidence of frequent dust plumes on millennial to centennial timescales in the Tarim Basin. Abrupt dust flux fluctuations during this transition, particularly during the Younger Dryas (YD), exhibit co-variation patterns similar to those seen in dust records from West Asia, East Asia, and Greenland, suggesting intercontinental climate teleconnections through the boreal westerly jet. We observe an anomalously high dust flux during the YD, not correlated with grain size. We attribute this circumstance to a stagnant westerly jet over the Tarim Basin for an extended period, leading to a prolonged duration of dust events. This could be due to a weakened Atlantic Meridional Overturning Circulation that triggered a southward shift and strengthening of the westerly jet, in conjunction with the North Atlantic Oscillation. These findings have broad implications for understanding regional dust emission dynamics and the coupling between dust emissions and atmospheric circulation on a global scale during the transition from the last glacial to the early Holocene.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104758"},"PeriodicalIF":4.0,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422575","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-resolution organic carbon isotope chemostratigraphy of the lower Aptian and the expression of Oceanic Anoxic Event 1a in the Tibetan Himalaya","authors":"Kaibo Han ,&nbsp;Zhiqin Liu ,&nbsp;Xi Chen ,&nbsp;Xuan Liu ,&nbsp;Huifang Guo ,&nbsp;Hanwei Yao ,&nbsp;Yi Zhang ,&nbsp;David B. Kemp ,&nbsp;Chengshan Wang","doi":"10.1016/j.gloplacha.2025.104759","DOIUrl":"10.1016/j.gloplacha.2025.104759","url":null,"abstract":"<div><div>Variations in carbon isotope (δ¹³C) values of Aptian marine strata are globally comparable and regarded as an important tool for the stratigraphic correlation of Aptian successions. The most remarkable feature of the δ¹³C curve of the Aptian is an abrupt negative excursion followed by a prominent positive excursion, which defines the early Aptian Oceanic Anoxic Event (OAE1a, ∼120 Ma). However, a complete and precise OAE1a record from eastern Tethys has yet to be established. Based on previously investigated integrated biostratigraphy, we present a high-resolution lower Aptian δ¹³C curve from bulk organic carbon through an expanded succession at the Chaqiela section in the Tibetan Himalaya. The depositional environment, couple with TOC/TN data, indicate that the organic matter was predominately sourced from marine plankton. As such, our results provide a record of secular changes in the δ¹³C of the dissolved carbon pool of the shallow sea on the southern margin of eastern Tethys.</div><div>The co-occurrence of glauconites and enrichments of the redox-sensitive trace elements (RSTEs) indicate largely suboxic bottom water conditions in the shallow marine eastern Tethys Ocean during OAE1a. Other paleoclimatic proxies suggest a relatively warm and humid paleo-environment during this time interval, with moderate to intense chemical weathering conditions revealed by chemical index of alteration (CIA) values.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104759"},"PeriodicalIF":4.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Growth patterns and geochemical characteristics of a colonial scleractinian cold-water coral in the South Chian Sea: A 500-year record of ocean environmental changes","authors":"Xuefeng Wang ,&nbsp;Xuefei Chen ,&nbsp;Kaiwen Ta ,&nbsp;Xuna Yin ,&nbsp;Lisheng Wang ,&nbsp;Miaohong He ,&nbsp;Wenfeng Deng ,&nbsp;Gangjian Wei ,&nbsp;Xiaotong Peng ,&nbsp;Xianhua Li","doi":"10.1016/j.gloplacha.2025.104747","DOIUrl":"10.1016/j.gloplacha.2025.104747","url":null,"abstract":"<div><div>Scleractinian cold-water corals (CWCs) are unique and prominent geological archives in the deep ocean, offering crucial insights into ocean dynamics and climate changes over time. Using scleractinian CWC skeletons to reconstruct paleoclimate often relies on combining data from multiple solitary cup corals or branching colonial corals. However, biomineralization strategies vary between species, and even within different skeletal structures (e.g. the corallite and the coenosteum) of the same species, leading to complex geochemical characteristics within coral skeletons, complicating our understanding of CWC growth patterns and the reconstruction of past ocean changes. In this study, we investigated the growth patterns of a colonial scleractinian CWC from the South China Sea using the U<img>Th dating technique and measured the geochemical compositions of the corallite and the coenosteum to evaluate their environmental significance. Our results indicate a budding rate approximately 2.8 polyps per decade, with linear extension rates between 0.47 and 0.57 mm/year, and radial thickening rates ranging from 0.014 to 0.022 mm/year. Significantly, the geochemical compositions, such as δ¹³C, δ¹⁸O, δ¹¹B, Sr/Ca, B/Ca, Ba/Ca, and U/Ca, differ between the corallite and coenosteum. Conversely, Mg/Ca and Li/Mg ratios remain consistent across both structures. These disparities likely reflect varying degrees of vital effects during the formation of different skeletal parts. Among the examined geochemical proxies, Ba/Ca and Li/Mg ratios provided clear signals of environmental changes over the past ∼500 years. Specifically, Ba/Ca ratios in both corallite and coenosteum exhibit a marked secular decline since the 1500s, suggesting a reduction in surface primary productivity or decreased ventilation of North Pacific intermediate waters. Additionally, intermediate water temperatures estimated from the Li/Mg ratios of these two structures collectively show a tendency to increase towards the twentieth century.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104747"},"PeriodicalIF":4.0,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late Eocene-Early Miocene paleoenvironmental shifts in the NW south American margin: Tectonic and climatic drivers inferred from benthic foraminifera","authors":"Raúl Trejos-Tamayo ,&nbsp;Darwin Garzón-Oyola ,&nbsp;Alejandra Rodríguez-Abaunza ,&nbsp;Fabrizio Frontalini ,&nbsp;Juan Pablo Betancur ,&nbsp;Fabian Gallego ,&nbsp;Andrés Pardo-Trujillo ,&nbsp;José-Abel Flores","doi":"10.1016/j.gloplacha.2025.104744","DOIUrl":"10.1016/j.gloplacha.2025.104744","url":null,"abstract":"<div><div>The strategic importance of northwestern South America, particularly along the southwestern Caribbean margin, lies in its critical role in global oceanic circulation and the impacts that marine ecosystems have experienced throughout the Cenozoic. Paleoenvironmental reconstruction in this region is essential for understanding how deep tropical ecosystems respond to changes in global climate and/or regional tectonic instability. This study presents a benthic foraminiferal record from a stratigraphic core (ANH-San Jacinto-1) in the central San Jacinto Fold Belt (SJFB) in northwestern South America. The record reveals significant shifts in nutrient input to the seafloor, bottom currents, and carbonate compensation depth (CCD) during the late Eocene to Early Miocene. The Eocene interval comprises two distinct environments: one near the base of the core, characterized by shallower, more energetic conditions with relatively well‑oxygenated waters and consistent nutrient supply, followed by a deeper environment with a high abundance of agglutinated foraminifera. The dominance of epifaunal taxa suggests nutrient influxes potentially driven by volcanic activity or fluvial systems in the southwestern Caribbean that may have depleted bottom-water oxygen.</div><div>Additionally, the high abundances of agglutinated species <em>Psammosiphonella cylindrica</em> and <em>P. discreta</em> indicate stronger and corrosive bottom waters during the late Eocene. At the beginning of the Oligocene, a notable shift in productivity and a deepening of the CCD led to a predominance of calcareous taxa, coinciding with global changes associated with the Eocene-Oligocene Transition. During the Oligocene, benthic foraminiferal communities appear to have been influenced by seasonal nutrient delivery, likely from different fluvial systems along the Caribbean margin of NW South America, possibly driven by a northward shift of the Intertropical Convergence Zone, directly impacting the SJFB. The upper Oligocene and Lower Miocene intervals record a significant increase in paleoproductivity, potentially linked to cooling events at high latitudes in the Atlantic Oceans or sustained organic influx from river systems in NW South America. This study enhances our understanding of the paleoenvironmental evolution in NW South America. It highlights the utility of benthic foraminiferal as sensitive proxies for tectonic, climatic, and oceanographic changes that shaped the paleoenvironments in this tropical region between the late Paleogene and early Neogene.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"248 ","pages":"Article 104744"},"PeriodicalIF":4.0,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}