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Potential effects of the Emeishan large igneous province on Capitanian marine anoxia in the Upper Yangtze region 峨眉山大型火成岩带对长江上游地区摩天岭海洋缺氧的潜在影响
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-09-10 DOI: 10.1016/j.gloplacha.2024.104579
Mingzhi Kuang , Haifeng Yuan , Wenjie Li , Bolin Zhang , Chen Shen , Qinren Xiao , Xihua Zhang , Hanlin Peng , Cong Chen , Tianjun Li
{"title":"Potential effects of the Emeishan large igneous province on Capitanian marine anoxia in the Upper Yangtze region","authors":"Mingzhi Kuang ,&nbsp;Haifeng Yuan ,&nbsp;Wenjie Li ,&nbsp;Bolin Zhang ,&nbsp;Chen Shen ,&nbsp;Qinren Xiao ,&nbsp;Xihua Zhang ,&nbsp;Hanlin Peng ,&nbsp;Cong Chen ,&nbsp;Tianjun Li","doi":"10.1016/j.gloplacha.2024.104579","DOIUrl":"10.1016/j.gloplacha.2024.104579","url":null,"abstract":"<div><p>The widespread Capitanian (late Guadalupian) marine anoxia/euxinia has long been regarded as a key driver of the end-Guadalupian (middle Permian) biotic crisis. However, the cause of this marine anoxia is debated, particularly regarding the influence of the Emeishan large igneous province (ELIP). To investigate the contribution of the ELIP to marine anoxia and the possible causal mechanisms, we undertook a conodont biostratigraphic and geochemical study of the middle Permian Maokou Formation in a platform-to-trough transect in the Upper Yangtze region, South China. Our results show that the depositional facies of the Maokou Formation changed from a carbonate ramp to an intra-platform trough within the <em>Jinogondolella</em> (<em>J.</em>) <em>altudaensis</em> zone in the northwestern Yangtze region, which can be attributed to the initial activity of the ELIP. Mantle-derived Sr inputs in the initial and main stages of the ELIP led to two decreases in <sup>87</sup>Sr/<sup>86</sup>Sr during the Capitanian, in the <em>J. shannoni</em>–<em>J. altudaensis</em> and <em>J. prexuanhanensis</em>–<em>J. xuanhanensis</em> zones. The elevated <sup>87</sup>Sr/<sup>86</sup>Sr values during the late Capitanian may have been due to enhanced continental weathering caused by rapid climate warming in response to subaerial eruptions of the ELIP. The deep-water anoxia–euxinia expanded during the middle Capitanian, as indicated by increased Mo<sub>EF</sub>/U<sub>EF</sub> and V/(V + Ni) values, along with the disappearance of burrows and appearance of small pyrite framboids in the <em>J. altudaensis</em> zone in the Cheng 20 well. However, shallow-water anoxia occurred during the late Capitanian (i.e., <em>J. prexuanhanensis</em>–<em>J. xuanhanensis</em> zone), as evidenced by positive Ce anomalies and losses of aerobic benthic species in the Erya section. Importantly, marine anoxia and negative δ<sup>13</sup>C<sub>carb</sub> excursions occurred synchronously, but earlier in deep water than in shallow water, potentially indicating an expansion of the oxygen minimum zone (OMZ). The deep-water anoxia corresponded to a decrease in <sup>87</sup>Sr/<sup>86</sup>Sr ratios and the appearance of an intra-platform trough in the <em>J. altudaensis</em> zone, whereas the shallow-water anoxia in the late Capitanian coincided with elevated <sup>87</sup>Sr/<sup>86</sup>Sr ratios. This suggests that the initial activity of the ELIP promoted the development of the OMZ in deep waters during the middle Capitanian, while the subaerial eruptions of the ELIP drove climate warming that led to the expansion of the OMZ into shallow-water platforms during the late Capitanian.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104579"},"PeriodicalIF":4.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142229855","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}
引用次数: 0
Western Mongolian Plateau exhibits increasing Holocene temperature 西蒙古高原显示全新世温度不断升高
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-09-10 DOI: 10.1016/j.gloplacha.2024.104577
Chong Huang , Xiaozhong Huang , Jinbao Li , Ling Wang , Lan Jiang , Lixiong Xiang , Jun Zhang , Yu Hu , Xiaoyan Mu , Min Zheng , Xiuxiu Ren , Tao Wang , Jiawu Zhang , Guoliang Lei , Otgonbayar Demberel , Xiaodong Liu , Natalia Rudaya , Antje Schwalb , Yanwu Duan , Jule Xiao , Fahu Chen
{"title":"Western Mongolian Plateau exhibits increasing Holocene temperature","authors":"Chong Huang ,&nbsp;Xiaozhong Huang ,&nbsp;Jinbao Li ,&nbsp;Ling Wang ,&nbsp;Lan Jiang ,&nbsp;Lixiong Xiang ,&nbsp;Jun Zhang ,&nbsp;Yu Hu ,&nbsp;Xiaoyan Mu ,&nbsp;Min Zheng ,&nbsp;Xiuxiu Ren ,&nbsp;Tao Wang ,&nbsp;Jiawu Zhang ,&nbsp;Guoliang Lei ,&nbsp;Otgonbayar Demberel ,&nbsp;Xiaodong Liu ,&nbsp;Natalia Rudaya ,&nbsp;Antje Schwalb ,&nbsp;Yanwu Duan ,&nbsp;Jule Xiao ,&nbsp;Fahu Chen","doi":"10.1016/j.gloplacha.2024.104577","DOIUrl":"10.1016/j.gloplacha.2024.104577","url":null,"abstract":"<div><p>The scarcity of Holocene winter temperature records from the core area of the Mongolian-Siberian High (MSH) hampers our understanding of the long-term evolution of the MSH and its modulation of the East Asian Winter Monsoon (EAWM). Here we use the body size of <em>Pediastrum</em>, a new and sensitive temperature proxy, from the sediments of Tolbo Lake in the western Mongolian Plateau, to reconstruct changes in winter temperature in the core area of the MSH during the Holocene. A large-scale investigation of modern <em>Pediastrum</em> body size across East Asia indicates that it is an accurate proxy indicator for mean winter temperature. The Holocene winter temperature based on <em>Pediastrum</em> body size from Tolbo Lake shows a general warming trend with the maximum at ∼2.6 ka. The current warming has attained the magnitude of the previous Holocene maximum, despite the underlying forcing being different. The mid-late Holocene winter warming in inland Eurasia may have weakened the MSH and reduced the intensity of the EAWM.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104577"},"PeriodicalIF":4.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142232170","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}
引用次数: 0
Climate variability in a 3.8 Ma old sedimentary record from the hyperarid Atacama Desert 超干旱阿塔卡马沙漠 3.8 马年沉积记录中的气候变异性
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-09-07 DOI: 10.1016/j.gloplacha.2024.104576
Felix L. Arens , Jenny Feige , Alessandro Airo , Christof Sager , Lutz Hecht , Lucas Horstmann , Felix E.D. Kaufmann , Johannes Lachner , Thomas Neumann , Norbert Nowaczyk , Ferry Schiperski , Peter Steier , Alexandra Stoll , Ulrich Struck , Bernardita Valenzuela , Friedhelm von Blanckenburg , Hella Wittmann , Lukas Wacker , Dirk Wagner , Pedro Zamorano , Dirk Schulze-Makuch
{"title":"Climate variability in a 3.8 Ma old sedimentary record from the hyperarid Atacama Desert","authors":"Felix L. Arens ,&nbsp;Jenny Feige ,&nbsp;Alessandro Airo ,&nbsp;Christof Sager ,&nbsp;Lutz Hecht ,&nbsp;Lucas Horstmann ,&nbsp;Felix E.D. Kaufmann ,&nbsp;Johannes Lachner ,&nbsp;Thomas Neumann ,&nbsp;Norbert Nowaczyk ,&nbsp;Ferry Schiperski ,&nbsp;Peter Steier ,&nbsp;Alexandra Stoll ,&nbsp;Ulrich Struck ,&nbsp;Bernardita Valenzuela ,&nbsp;Friedhelm von Blanckenburg ,&nbsp;Hella Wittmann ,&nbsp;Lukas Wacker ,&nbsp;Dirk Wagner ,&nbsp;Pedro Zamorano ,&nbsp;Dirk Schulze-Makuch","doi":"10.1016/j.gloplacha.2024.104576","DOIUrl":"10.1016/j.gloplacha.2024.104576","url":null,"abstract":"<div><div>The hyperarid Atacama Desert is one of the driest and oldest deserts on Earth, rendering it a valuable climate archive. However, unraveling its past climate is particularly challenging and the few studied paleoclimate records of the region reveal strong temporal and spatial variabilities. To enhance our understanding of these dynamics we investigated a sedimentary record in the Yungay valley located in the southern hyperarid Atacama Desert. We employed paleomagnetic and radiocarbon dating, and for the first time for Atacama Desert sediments, a meteoric <sup>10</sup>Be/<sup>9</sup>Be based method for determining the depositional age. The respective 4.20 m deep profile comprises a lower alluvial fan deposit with a maximum age of 3.8 ± 0.8 Ma, and an upper 1.84 m thick clay pan deposit that has accumulated over the last 19 ka. Different proxies including grain size, salt concentration, and elemental composition indicate an aridity increase around 2.3 Ma ago and repeated dry and wet phases during the late Pleistocene and the Holocene. The latter climatic shifts can be assigned to variabilities of the South American Summer Monsoon and El Niño Southern Oscillation with moisture sources from the Atlantic and the Pacific Ocean, respectively. This study provides deeper insights into the heterogeneous climate of the hyperarid Atacama Desert and underlines the importance of interdisciplinary investigations to decipher climate systems and their effect on potential habitable regions in such an extreme environment.</div></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104576"},"PeriodicalIF":4.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142321944","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}
引用次数: 0
Sensitivity of western Pacific subtropical high to regional sea surface temperature changes 西太平洋副热带高压对区域海面温度变化的敏感性
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-09-06 DOI: 10.1016/j.gloplacha.2024.104565
Lingyu Zhou , Yan Xia , Chen Zhou , Chuanfeng Zhao , Fei Xie , Lu Dong
{"title":"Sensitivity of western Pacific subtropical high to regional sea surface temperature changes","authors":"Lingyu Zhou ,&nbsp;Yan Xia ,&nbsp;Chen Zhou ,&nbsp;Chuanfeng Zhao ,&nbsp;Fei Xie ,&nbsp;Lu Dong","doi":"10.1016/j.gloplacha.2024.104565","DOIUrl":"10.1016/j.gloplacha.2024.104565","url":null,"abstract":"<div><p>The western Pacific subtropical high (WPSH) exerts significant influence on the climate of the Pacific region and East Asia. In this study, we systematically examined the responses of the WPSH intensity and position to regional sea surface temperature (SST) changes using idealized SST patch experiments with a climate model. Our findings reveal that the WPSH intensity is most sensitive to northern tropical SST during the boreal summer. Specifically, warming in the tropical Indian Ocean, eastern Pacific, and tropical North Atlantic contributes to a strengthening of the WPSH, whereas warming in the tropical western Pacific leads to its weakening. SST warming enhances local convergence and convection, which can modify the WPSH intensity via modulating the strength of tropical zonal circulation. Additionally, it is found that the SST-induced enhancement (weakening) of the WPSH is always accompanied with a westward extension (eastward retreat) of the WPSH. Furthermore, the response of the WPSH to tropical SST changes exhibits nonnegligible nonlinearity, which indicates the importance of multi-ocean interaction in determining the WPSH response to global surface warming.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104565"},"PeriodicalIF":4.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168641","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}
引用次数: 0
A 70-year record reveals the poleward shift of tropical cyclone tracks in the east China coastal ocean is twice that of landward shift 70 年的记录显示,中国东部近海热带气旋路径的极地偏移是陆地偏移的两倍
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-09-05 DOI: 10.1016/j.gloplacha.2024.104566
Chaoran Xu , Yang Yang , Jianjun Jia , Jeremy D. Bricker , Ya Ping Wang
{"title":"A 70-year record reveals the poleward shift of tropical cyclone tracks in the east China coastal ocean is twice that of landward shift","authors":"Chaoran Xu ,&nbsp;Yang Yang ,&nbsp;Jianjun Jia ,&nbsp;Jeremy D. Bricker ,&nbsp;Ya Ping Wang","doi":"10.1016/j.gloplacha.2024.104566","DOIUrl":"10.1016/j.gloplacha.2024.104566","url":null,"abstract":"<div><p>Analyzing the spatial-temporal changes in tropical cyclone (TC) tracks in the east China coastal ocean (ECCO) to quantify the magnitude of poleward and landward migration of TCs is of significant importance for coastal disaster mitigation and planning due to its susceptibility to the impacts of TCs. In this study, the TCs that affected the ECCO from 1949 to 2022 are classified into three typical types of tracks using the k-means clustering method, mass moments, and track interpolation based on TC location, shape, and intensity information. Type 1 is a northwestward track, Type 2 is a northwest to northeast-turning track, and Type 3 is a northwest to northeast-turning offshore track. Type 1 tracks mainly make landfall in southern China, while Type 2 predominantly makes landfall in eastern China. Moreover, the proportion of Type 1 decreases while their landfall percentage increases over time, and the proportion of Type 2 tracks is increasing. The probability of TC effects on the eastern and northern parts of the ECCO is increasing, and the boundary where the TC center reaches after landfall is shifting landward. During the period from 1994 to 2022, there has been a significant migration in TC tracks, with the mean centroid of the TCs affecting the ECCO shifting westward by 0.66° in longitude and northward by 1.26° in latitude, which means the magnitude of the poleward shift is about twice that of the landward shift. This migration appears to have been pre-conditioned by a combined influence of a weakening westward steering flow, reduced vertical wind shear, and warmer sea surface temperature Our findings provide valuable insights into the longitudinal and latitudinal migration of TC tracks and have important implications for disaster prevention, mitigation planning, and the adjustment of crucial coastal protection zones in the ECCO and similar regions around the globe.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104566"},"PeriodicalIF":4.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168002","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}
引用次数: 0
Enhanced deep-water circulation facilitated rare earth elements enrichment in pelagic sediments from the northwestern Pacific Ocean 深水环流的增强促进了西北太平洋浮游沉积物中稀土元素的富集
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-09-03 DOI: 10.1016/j.gloplacha.2024.104564
Dongjie Bi , Xuefa Shi , Mu Huang , Fangyu Shen , Miao Yu , Ying Zhang , Fengdeng Shi , Jihua Liu
{"title":"Enhanced deep-water circulation facilitated rare earth elements enrichment in pelagic sediments from the northwestern Pacific Ocean","authors":"Dongjie Bi ,&nbsp;Xuefa Shi ,&nbsp;Mu Huang ,&nbsp;Fangyu Shen ,&nbsp;Miao Yu ,&nbsp;Ying Zhang ,&nbsp;Fengdeng Shi ,&nbsp;Jihua Liu","doi":"10.1016/j.gloplacha.2024.104564","DOIUrl":"10.1016/j.gloplacha.2024.104564","url":null,"abstract":"<div><p>The lack of knowledge about the enrichment mechanism of rare earth elements and yttrium (REY) in deep-sea sediments is impeding the development of theories and exploration strategies for pelagic REY-rich sediments. Ocean circulation variability seems to be crucial in enriching REY in pelagic sediments, which, however, has not been extensively studied. Here, we examined the Pb-Nd isotopic signals of bottom water recorded by the authigenic ferromanganese oxyhydroxide fractions, as well as the Mn/Al and Mn/Ti ratios of bulk samples from a well-dated sediment core in the northwestern Pacific Ocean. These proxies consistently indicate that enhanced deep-water circulation occurred in the study area at ∼11.5–9.5 Ma, which was most likely to be caused by changes in the flow path of bottom currents. The age of this distinct event consists with the forming age of highly REY-rich sediments. We propose that enhanced deep-water circulation in seamount areas could increase the flux of micronodules and fish debris into the pelagic sediments, facilitating the scavenging of REY from seawater. Our findings establish a connection between enhanced deep-water circulation and the enrichment of REY in pelagic sediments.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104564"},"PeriodicalIF":4.0,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142168642","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}
引用次数: 0
Late Triassic carbon isotope anomalies in the Canadian Cordillera: Paleoenvironmental disturbances associated with the Norian/Rhaetian boundary and end-Triassic mass extinction event 加拿大科迪勒拉山系晚三叠世碳同位素异常:与纪元/雷蒂纪边界和三叠纪末大灭绝事件相关的古环境扰动
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-08-30 DOI: 10.1016/j.gloplacha.2024.104563
Jerry Z.X. Lei , Jon M. Husson , Martyn L. Golding , Connor S. van Wieren , Michael J. Orchard , Andrew H. Caruthers , Elizabeth S. Carter
{"title":"Late Triassic carbon isotope anomalies in the Canadian Cordillera: Paleoenvironmental disturbances associated with the Norian/Rhaetian boundary and end-Triassic mass extinction event","authors":"Jerry Z.X. Lei ,&nbsp;Jon M. Husson ,&nbsp;Martyn L. Golding ,&nbsp;Connor S. van Wieren ,&nbsp;Michael J. Orchard ,&nbsp;Andrew H. Caruthers ,&nbsp;Elizabeth S. Carter","doi":"10.1016/j.gloplacha.2024.104563","DOIUrl":"10.1016/j.gloplacha.2024.104563","url":null,"abstract":"<div><p>The Late Triassic was a particularly turbulent interval of the geologic past, marked by repeated paleoenvironmental instability culminating in the end-Triassic mass extinction (ETME). These episodes of disturbance are associated with enhanced volcanism, harbinger of the eventual break-up of Pangea. As evidenced by geochemical signals in the marine carbon isotope record, these events were often significant enough to disrupt the global carbon cycle. However, the duration and extent of ETME-associated disturbances leading up to the Triassic/Jurassic boundary (TJB) remain contentious. The present study investigates eight stratigraphic sections from across British Columbia to create a comprehensive Panthalassan carbon isotope record spanning the Norian to early Hettangian. Three distinct negative excursions are observed: an excursion proximal to the Norian/Rhaetian boundary (NRB), another excursion within the Rhaetian, and a final excursion coinciding with the TJB. This is generally consistent with prior studies, but suggests there may be no clear distinction between the negative excursion associated with the NRB, and the oldest Rhaetian “precursor” excursion proposed to be associated with the TJB. Several of the excursions observed in the present study are too large in magnitude to plausibly reflect global ocean water chemistry (∼10 ‰ compared to the expected ∼3 ‰), indicating some local mechanism was amplifying these carbon isotope excursions. A potential explanation is increased organic carbon respiration in restricted marine environments, triggered during episodes of paleoenvironmental disturbance. Regardless, this evidence for repeated carbon isotope excursions supports paleontological data suggesting that the ETME is not a singular and geologically instantaneous event at the TJB, but is instead the amalgamation of several turnovers beginning as early as the NRB.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"242 ","pages":"Article 104563"},"PeriodicalIF":4.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0921818124002108/pdfft?md5=e01cd8d1e67515ed40196456c4990ac1&pid=1-s2.0-S0921818124002108-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142172628","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}
引用次数: 0
A refined model for the mechanisms of Precambrian phosphorite formation 前寒武纪磷酸盐岩形成机制的完善模型
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-08-30 DOI: 10.1016/j.gloplacha.2024.104562
Quzong Baima , Xiangkun Zhu , Weibing Shen , Zhaofu Gao , Bin Yan , Yuelong Chen
{"title":"A refined model for the mechanisms of Precambrian phosphorite formation","authors":"Quzong Baima ,&nbsp;Xiangkun Zhu ,&nbsp;Weibing Shen ,&nbsp;Zhaofu Gao ,&nbsp;Bin Yan ,&nbsp;Yuelong Chen","doi":"10.1016/j.gloplacha.2024.104562","DOIUrl":"10.1016/j.gloplacha.2024.104562","url":null,"abstract":"<div><p>Despite the economic and scientific importance of Precambrian phosphorites, our understanding of the mechanism leading to their formation remains limited, including for the largest phosphogenic episode in the late Neoproterozoic. To improve our understanding of Precambrian phosphorite formation, we combined sedimentology, petrography, and elemental, and Fe-C isotopic analyses to study the two main phosphorite beds (the lower and upper phosphorite beds) in the Ediacaran Doushantuo Formation, Zhangcunping area, South China. The phosphorites consist mainly of granular textures characterized by densely packed grains, some of which are coated with secondary phosphate growth. However, there are notable differences in the mineralogy, microfossil assemblages, and elemental contents of the two beds. The lower phosphorites have no Ce anomaly, and relatively low Y/Ho ratios and positive δ<sup>56</sup>Fe values (0.04–0.30 ‰, average of 0.19 ‰). In contrast, the upper phosphorites have negative Ce anomalies and higher Y/Ho ratios and near-zero δ<sup>56</sup>Fe values (−0.29–0.19 ‰ (average of −0.01 ‰). These observations suggest that the lower phosphorites formed in anoxic-suboxic environments, whereas the upper phosphorites formed in relatively oxygenated environments. The δ<sup>13</sup>C<sub>carb</sub> values of the phosphorites range from −3.97 ‰ to 1.71 ‰ (average of −1.56 ‰), and are lighter than values in dolostones (−0.52 ‰ to 4.39 ‰, average of 2.02 ‰). This suggesting that formation of the Doushantuo phosphorites was influenced by degradation of organic matter in an ocean with high primary productivity. The lower phosphorites, which were also regulated by Fe redox pumping, have positive δ<sup>56</sup>Fe values, along with the presence of pyrite framboids and iron oxides, suggesting deposition near the Fe-redox boundary where extensive Fe cycling. The upper phosphorites show positive correlations between Mn and Fe, and Mn/Fe and P<sub>2</sub>O<sub>5</sub>, suggesting formation near the Mn boundary with extensive Mn cycling, primarily mediated by Mn redox pumping. Sedimentological observation indicate that primary phosphates were concentrated into granular phosphorites by winnowing processes following primary precipitation. Accordingly, we propose a refined model for Precambrian phosphorite formation in which degradation of organic matter, Fe and Mn pumping, and physical reworking of deposits co-evolve and interact within a dynamic Precambrian redox environment. Our model provides a reasonable explanation for the distribution of global phosphorite deposits throughout geological history.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104562"},"PeriodicalIF":4.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142136071","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}
引用次数: 0
Increasing heat waves frequencies over India during post-El Niño spring and early summer seasons 在厄尔尼诺现象后的春季和初夏季节,印度上空的热浪频率越来越高
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-08-30 DOI: 10.1016/j.gloplacha.2024.104561
G.Ch. Satyanarayana , Sambasivarao Velivelli , K. Koteswara Rao , Jasti S. Chowdary , Anant Parekh , C. Gnanaseelan
{"title":"Increasing heat waves frequencies over India during post-El Niño spring and early summer seasons","authors":"G.Ch. Satyanarayana ,&nbsp;Sambasivarao Velivelli ,&nbsp;K. Koteswara Rao ,&nbsp;Jasti S. Chowdary ,&nbsp;Anant Parekh ,&nbsp;C. Gnanaseelan","doi":"10.1016/j.gloplacha.2024.104561","DOIUrl":"10.1016/j.gloplacha.2024.104561","url":null,"abstract":"<div><p>The increasing frequency of extreme Heat Waves (HWs) has generated significant societal impacts in recent years. This study used different observational datasets to investigate the HW characteristics over India during the post-El Niño spring and early summer seasons (April to June; AMJ). Analysis suggests that HW days are more prevalent over India, predominantly increased in south-central and northwest India, during the decaying phase of strong El Niño years. It is found that anomalous anticyclone circulation accompanied by high pressure extending from the Western North Pacific region towards the Bay of Bengal and India is responsible for enhanced HW days and intensity during the AMJ of strong El Niño decay years. This anomalous anticyclone-induced downdraft reduces the specific humidity in the lower troposphere, leading to decreased cloud cover over India. As a result, shortwave radiation is enhanced at the surface, which causes abnormal HWs over India. During the decaying phase of strong El Niño years, the HW days over India contributed to an increase in the frequency of Discomfort Index hours (above 28 °C), maximum temperatures exceeding 40 °C (hours per day), and Universal Thermal Climate Index days above 38 °C and 46 °C during the spring and early summer months, especially in the East Coast, central, and northwestern parts of India. Thus, proper prediction of large-scale atmospheric circulation over the Indo-western Pacific region during El Niño can help to predict the HW conditions three months in advance. This would help to implement suitable adaptation measures and put into practice strong mitigation policies to limit the increased risk of such events during AMJ of El Niño decay years.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104561"},"PeriodicalIF":4.0,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142097054","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}
引用次数: 0
Corrigendum to “Global-scale daily riverine DOC fluxes from lands to the oceans with a generic model” [Global and Planetary Change, volume 194 (November 2020)] "使用通用模型计算全球尺度陆地至海洋的每日河流 DOC 通量"[《全球和行星变化》,第 194 卷(2020 年 11 月)] 更正
IF 4 1区 地球科学
Global and Planetary Change Pub Date : 2024-08-27 DOI: 10.1016/j.gloplacha.2024.104551
C. Fabre, S. Sauvage, J.-L. Probst, J.M. Sánchez-Pérez
{"title":"Corrigendum to “Global-scale daily riverine DOC fluxes from lands to the oceans with a generic model” [Global and Planetary Change, volume 194 (November 2020)]","authors":"C. Fabre,&nbsp;S. Sauvage,&nbsp;J.-L. Probst,&nbsp;J.M. Sánchez-Pérez","doi":"10.1016/j.gloplacha.2024.104551","DOIUrl":"10.1016/j.gloplacha.2024.104551","url":null,"abstract":"","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"241 ","pages":"Article 104551"},"PeriodicalIF":4.0,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S092181812400198X/pdfft?md5=5b4dd43df6e1a7f731ad446bfa63d553&pid=1-s2.0-S092181812400198X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142157640","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}
引用次数: 0
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