Global and Planetary Change最新文献

{"title":"Precipitation dynamics and its interactions with possible drivers over global highlands","authors":"Haider Abbas ,&nbsp;Azfar Hussain ,&nbsp;Ming Xu","doi":"10.1016/j.gloplacha.2024.104529","DOIUrl":"10.1016/j.gloplacha.2024.104529","url":null,"abstract":"<div><p>The climate and ecosystem in the highland regions are fragile and vulnerable to climate change. This study used ERA5, CRU, and CHIRPS at 0.5° × 0.5° resolution to assess spatiotemporal precipitation trends over global highlands from 1981 to 2021. The Standardized anomaly index (SAI) is used to evaluate the comparative anomalies between the datasets, while the Mann-Kendall and Sen Slope estimator tests the precipitation trends. Empirical orthogonal function (EOF), pixel-wise correlation, and detrended cross-correlation (DCCA) were employed to investigate the dominant precipitation patterns and their relationships with regional climatic impacts, while the wavelet analysis determines ocean-atmospheric factors in the time-frequency domain. The SAI correlation strongly relates to CRU-CHIRPS for precipitation estimates in North America (NA) R² = 0.84, Europe R² = 0.71, and South America (SA), whereas CRU-ERA5 showed better results in the Asian highlands R² = 0.29, highlighting regional differences in the precipitation dynamics. For precipitation, EOF1 showed a positive variance in most highland regions, but a negative variance prevailed in the Tibetan Plateau (TP), whereas EOF1–2 explained ∼32%, 33%, and 30% variance globally for ERA, CRU, and CHRIPS, respectively. A strong positive correlation is observed between precipitation and mean temperature (TMP) in North America (NA) and the European Alps. However, a significant negative correlation prevailed in the TP and some parts of NA, indicating that these factors can significantly influence the precipitation dynamics in the highlands. Additionally, Detrended Cross-Correlation Analysis (DCCA) has verified that there are positive correlations between precipitation and key climatic factors such as total column water vapor (TCWV), potential evaporation (PEV), and soil moisture (SM). In addition, the influence of ocean-atmospheric (interannual and decadal) coherence patterns originating from the Pacific and Atlantic Oceans indicates a significant impact on precipitation variability, especially in the Asian highlands. This study can contribute to a better understanding of mechanisms and serve as a reference for forecasting precipitation dynamics to develop corresponding strategies in global highlands.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104529"},"PeriodicalIF":4.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141842157","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":"Temperature modulation of Northern Mid-Latitude Westerly winds intensity and displacement across the warm Pliocene","authors":"Ting Chen ,&nbsp;Qingsong Liu ,&nbsp;Hong Ao ,&nbsp;David B. Ryves","doi":"10.1016/j.gloplacha.2024.104531","DOIUrl":"10.1016/j.gloplacha.2024.104531","url":null,"abstract":"<div><p>The mid-latitude westerly winds are fundamental components of the Earth's climate system. However, their detailed variations during the entire Pliocene, a critical epoch often considered the closest analogue to future climate scenarios, remain poorly constrained. Here, we investigate the continuous, long-term evolution of Northern Hemisphere Mid-latitude Westerly winds (NHMW) between 6.5 and 2.5 Ma, using diatoms, aeolian dust grain size, and chemical weathering conditions from a sediment core in the central-north Pacific Ocean. Our records suggest that NHMW weakened and shifted northward from ∼5.8 to 4.4 Ma, followed by a sustained strengthening and equatorward shift after ∼4.4 Ma. NHMW dynamics during the Pliocene were linked tightly to the sea surface temperature gradient between tropical and temperate regions and affected the strength of the Asian Summer Monsoon (ASM), with weaker and more poleward NHMW increasing the intensity of and rainfall generated by the ASM. These findings underscore the importance of past dynamics of NHMW for predicting the hydroclimatological impacts of future global climate change on the functioning of major regional ocean-atmosphere and rainfall systems as the earth continues to warm.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104531"},"PeriodicalIF":4.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141851763","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":"Anaerobic oxidation of methane and greigite formation: Evidence of isotopically heavy pyrite in Pleistocene coastal sediments from the South Yellow Sea","authors":"Xiaoxiao Yu ,&nbsp;Xi Mei ,&nbsp;Jianxing Liu ,&nbsp;Baichuan Duan ,&nbsp;Rui Zhang ,&nbsp;Tiegang Li ,&nbsp;Gangjian Wei ,&nbsp;Mang Lin","doi":"10.1016/j.gloplacha.2024.104530","DOIUrl":"10.1016/j.gloplacha.2024.104530","url":null,"abstract":"<div><p>Diagenetic alteration of magnetic minerals, driven by closely linked C-S-Fe cycles, is highly likely to complicate the paleomagnetic record. In addition to the anomalous diagenetic paleomagnetic signatures caused by ferromagnetic greigite growth, pyrite sulfur isotope compositions are often “heavy” (i.e., δ³⁴S_pyr &gt; 0). However, the dependencies and mechanistic origins of these signatures remain controversial. This study presents a high-resolution δ³⁴S_pyr record of a long sediment core collected from the South Yellow Sea, China. Ferromagnetic greigite is prominently identified in two coastal deposits within this core. The δ³⁴S_pyr values of these coastal deposits are isotopically (super) heavy, ranging from −10.6 to 22.8‰ and from −14.5 to 26.5‰, with mean and 1σ values of 5.9 ± 10.3‰ (<em>n</em> = 15) and 12.2 ± 9.8‰ (<em>n</em> = 33), respectively. Additionally, magnetic parameters show positive trends with δ³⁴S_pyr values throughout the sediment core. These positive trends, along with the enrichment of ferrous iron and sedimentary microtextural evidence of the authigenic growth sequence of framboidal pyrite, siderite, euhedral pyrite, and greigite, indicate that anaerobic oxidation of methane (AOM) is a fundamental factor for ferromagnetic greigite formation in coastal sediments with sulfate limitation. We estimate the delay time of greigite formation relative to the depositional age of surrounding sediments to be a few hundred years due to the rapid sedimentation rates and shallow burial depths of the sulfate-methane transition zone (SMTZ) in coastal deposits. Conversely, the deep burial of SMTZ likely suggests that a longer delay time is prevailing for greigite formation in hemipelagic sediments. This study highlights the role of AOM in controlling the formations of greigite and coeval (super) heavy pyrite.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104530"},"PeriodicalIF":4.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141851886","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":"The potential role of insolation in the long-term climate evolution since the early Pleistocene","authors":"Xiaolin Ma ,&nbsp;Mengfei Yang ,&nbsp;Yachen Sun ,&nbsp;Haowen Dang ,&nbsp;Wentao Ma ,&nbsp;Jun Tian ,&nbsp;Qian Jiang ,&nbsp;Lang Liu ,&nbsp;Xiaobo Jin ,&nbsp;Zhangdong Jin","doi":"10.1016/j.gloplacha.2024.104526","DOIUrl":"10.1016/j.gloplacha.2024.104526","url":null,"abstract":"<div><p>The distribution of insolation over time and space is a significant driver of climate change on orbital timescales. However, the influence of insolation on long-term climate evolution remains poorly understood due to the absence of a discernible long-term trend regulated by Earth's orbit. In this study, we present a sea surface temperature anomaly (SSTA) stack spanning the past 2 Myr, compiled from 26 millennial-resolved records obtained from the global ocean. The global average sea surface temperature (SST) reveals a 405-kyr cycle, as well as a gradual decrease of 2.34 ± 1.05 °C (1σ) from 2000 ka to 940 ka, followed by a period of relative stability. We introduce an index named the integral of annual mean insolation anomaly (IAMIA), which quantifies the continuous departure of annual mean insolation (AMI) from its “normal” cycle over a specific time interval. We find that the SST leads the variations in AMI and IAMIA at the 405-kyr band, intimating that the cycle evident in global SST does not originate from the changes of eccentricity but rather stems from harmonic or combination tones. Notably, IAMIA exhibits a fundamental shift at 935 ka, coinciding with the “900-ka event” observed in the SST. Modeling results support that the “900-ka event” could be driven by the change of cumulative insolation. Additionally, IAMIA underscores the important role of insolation in Pleistocene climate change on the long-term trend through the cumulative response of ocean heat content (OHC) to successive small step-wise insolation changes. Furthermore, we hypothesize that the fundamental changes of insolation around 935 ka, transitioning from a positive state characterized by substantial amplitude to a negative state typified by diminished amplitude, facilitated the onset and progression of the mid-Pleistocene transition (MPT). This investigation provides invaluable insights into the role of insolation in long-term climate evolution.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104526"},"PeriodicalIF":4.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769044","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":"Interannual variation of the westward ridge point of the Western Pacific subtropical high in boreal winter","authors":"Shu Gui ,&nbsp;Jinxin Cheng ,&nbsp;Ruowen Yang ,&nbsp;Qiulan He ,&nbsp;Zizhen Dong ,&nbsp;Ji Ma ,&nbsp;Qucheng Chu ,&nbsp;Meiyi Hou","doi":"10.1016/j.gloplacha.2024.104528","DOIUrl":"10.1016/j.gloplacha.2024.104528","url":null,"abstract":"<div><p>This study adopts a novel dynamic index of the westward ridge point (WRP) of the western Pacific subtropical high (WPSH) to investigate the interannual variation of the WPSH in boreal winter. The WRP index based on the theory of gradient wind approximation is particularly suitable for boreal winters. The WRP index comprises two dimensions that depict the zonal and meridional movement of the WPSH, respectively. There is a significant positive correlation between the zonal WRP index and the meridional WRP index. When the WPSH gets stronger, the WRP and the WPSH shift equatorward while advancing westward, and vice versa. The zonal and meridional shifts of the WPSH have distinct impact on the climate anomalies in the western North Pacific and East Asia. The northward shift of the WPSH characterizes a cyclonic-anticyclonic pair over western North Pacific, whereas the eastward shift of the WPSH characterizes a cyclonic anomaly over the subtropical western North Pacific. The anomalies of precipitation and surface air temperature vary accordingly. The meridional shift of the WPSH is closely associated with the El Niño-Southern Oscillation (ENSO) Sea Surface Temperature (SST) anomalies. The WRP index also demonstrates robust predictability in the hindcast data from ENSEMBLES, suggesting its far-reaching potential for climate prediction.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104528"},"PeriodicalIF":4.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769042","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":"Holocene dust storm variations across northern monsoonal Asia and arid central Asia: Contrasting impacts of climate change","authors":"Shengqian Chen ,&nbsp;Jianbao Liu ,&nbsp;Shuai Ma ,&nbsp;Yijiao Fan ,&nbsp;Jia Jia ,&nbsp;Jianhui Chen ,&nbsp;Fahu Chen","doi":"10.1016/j.gloplacha.2024.104524","DOIUrl":"10.1016/j.gloplacha.2024.104524","url":null,"abstract":"<div><p>Arid inner Asia, encompassing northern monsoonal Asia (NMA) and arid central Asia (ACA), is the world's second largest dust source region, emitting large quantities of dust particles that travel vast distances around the globe. Previous studies have revealed that the precipitation/moisture variations between NMA and ACA show an out-of-phase or anti-phase relationship on a multi-millennial timescale during the Holocene. However, considering the profound impact of precipitation and related vegetation changes on dust storms, it is unclear whether disparities exist in the variations and mechanisms governing Holocene dust storms between these two regions. Here we use a compilation of Holocene dust storm records from both NMA and ACA, combined with proxy–model comparisons, to demonstrate a consistent temporal pattern of dust storm activity between these regions, with an overall increasing trend on a multi-millennial timescale during the Holocene. Comparison of these dust storm records with regional climate records reveals that surface landscape dominated by the summer monsoon precipitation were the dominant controls on dust storm activity in NMA during the Holocene. In contrast, given the Holocene wetting trend observed for ACA, we propose that precipitation had only a limited influence on modulating the regional dust storms in this region; furthermore, the increasing frequency of dust storms cannot be attributed to decreasing winter monsoon intensity. Instead, we argue that the intensified dust storms in ACA during the late Holocene were triggered by the increased strength and northward (southward) movement of the spring (summer) westerly jet. By revealing the differences in the mechanisms of dust storms across arid inner Asia, our findings provide a scientific basis for implementing policies for dust storm management that can be adapted to meet specific local conditions.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104524"},"PeriodicalIF":4.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769037","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":"The Siberian High drove increasing dust storm activity on the Tibetan Plateau on the centennial scale during the past 2000 years","authors":"Zhitong Chen ,&nbsp;Shengqian Chen ,&nbsp;Jifeng Zhang","doi":"10.1016/j.gloplacha.2024.104525","DOIUrl":"10.1016/j.gloplacha.2024.104525","url":null,"abstract":"<div><p>Precipitation records from the Tibetan Plateau (TP) for the past ∼2000 years show a north–south dipole pattern. Precipitation is one of the main factors affecting dust storms in this region, but it is unclear whether regional differences exist in dust storm activity and its driving mechanisms across the entire TP, and whether these mechanisms were consistent on the Holocene millennial scale and the centennial scale during the past 2000 years. To address this uncertainty, we reconstructed a high-resolution record of dust storm activity for the past ∼2000 years from an undisturbed lake site on the southwestern TP, in an area which is poorly investigated. We found that dust storm activity gradually increased over the past 2000 years and peaked during the Little Ice Age (LIA). Comparison with other dust storm records revealed a consistent trend of dust storm intensification across the entire TP, which contradicts the previously proposed north–south dipole pattern of precipitation variation. To explain this, we propose that dust storm outbreaks across the entire TP during the LIA were driven by the spatial coupling between TP dust source areas and cold fronts resulting from an enhanced Siberian High (SH). Compared with the driving mechanism of the millennial-scale variations of the westerly jet during the Holocene, there was a clear shift to SH intensity as the principal driving mechanism of TP dust storms on the centennial timescale. Overall, our findings demonstrate different degrees of importance of these two hemispheric-scale circulations for dust storm activity across the entire TP, on different time scales, forming a scientific foundation for dust storm management on a global scale.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104525"},"PeriodicalIF":4.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769038","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":"Contourite-like deposits suggest stronger-than-present circulation in the Plio-Pleistocene Red Sea","authors":"Neil C. Mitchell ,&nbsp;Marco Ligi ,&nbsp;Jonas Preine ,&nbsp;Diederik Liebrand ,&nbsp;Moamen Ali ,&nbsp;Alessandro Decarlis","doi":"10.1016/j.gloplacha.2024.104527","DOIUrl":"10.1016/j.gloplacha.2024.104527","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Red Sea Deep Water is presently slow-moving, but was this true of the earlier Plio-Pleistocene (PP)? In seismic reflection records, the PP deposits are distorted by halokinetic deformation of their underlying Miocene evaporites. However, if reflections are flattened to a prominent reflector representing the top of the Miocene, they reveal mounded deposits within the earlier PP along both sides of the sea. Off Egypt, a plastered drift occurs along a salt wall. In the central Red Sea, they are mounded drifts. Seismic reflections from these deposits change shape gradually upwards to the modern seabed, which is commonly flatter, suggesting a gradual change in depositional conditions. To explain their origins, we appeal to other evidence. DSDP cores from the Late Pleistocene contain the rigid aragonite cements formed by restricted conditions, but not the lower and middle PP. Furthermore, mid-PP sedimentary δ&lt;sup&gt;18&lt;/sup&gt;O values are similar to global ocean δ&lt;sup&gt;18&lt;/sup&gt;O for that time, not enhanced as expected from excess evaporation. These data suggest that there was a greater exchange of Red Sea waters with the Indian Ocean during the mid-PP. That exchange may have allowed waters densified by evaporation in shallow regions of the northern Red Sea to flow south vigorously (the mounds would then be contourites). Alternatively, as the Pliocene seabed was shallower, wind-driven eddies may have affected more of the water column. Overall, the results indicate for the first time that deep circulation was stronger in the earlier PP compared with the present day. That circulation needs to be considered when evaluating organism dispersions across the Red Sea, regional climate, and influence of Red Sea Outflow Water on Indian Ocean Intermediate Water.&lt;/p&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Plain language summary&lt;/h3&gt;&lt;p&gt;During the Pliocene (about 3–5 million years ago), temperatures on Earth's surface were similar to those predicted in some models of Earth's future climate. This has led to researchers becoming interested in studying geological evidence of conditions during the Pliocene as a clue to Earth's future. In detail, however, the comparison may not be exact. In our article, we describe mounds of sediment that were originally formed on the bed of the Red Sea in the Pliocene. They appear similar to snow drifts, and like snow drifts, may have formed under steady currents. Sea water becomes dense with evaporation (making it more saline). At the present day, dense water created in the Gulf of Suez cascades down into the deep Red Sea as a slow current. Perhaps such movements were more vigorous in the Pliocene, helped by the water escaping through a deeper barrier in the south into the Indian Ocean? Alternatively, these mounds were formed by giant eddies, such as those on the surface of the modern Red Sea, which are moved by strong winds. In either case, the deep waters of the Pliocene Pliocene Red Sea were more vigorously moving compared to the quiescent deep waters of t","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104527"},"PeriodicalIF":4.0,"publicationDate":"2024-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0921818124001747/pdfft?md5=b2dc3ee371689ff83c00447b7a245c8d&pid=1-s2.0-S0921818124001747-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769043","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":"Enhanced mixing of north Pacific deep western-boundary currents after Panama seaway closure","authors":"Xiaodong Jiang ,&nbsp;Xiaoming Sun ,&nbsp;James R. Hein ,&nbsp;Xuefa Shi ,&nbsp;Yao Guan ,&nbsp;Yumin Chou ,&nbsp;Weijie Zhang ,&nbsp;Qingsong Liu","doi":"10.1016/j.gloplacha.2024.104514","DOIUrl":"10.1016/j.gloplacha.2024.104514","url":null,"abstract":"<div><p>The near closure of the Panama Seaway during the late Miocene resulted in the modification of deep-ocean currents and the formation of modern oceanic circulation. However, it is unclear how this closure impacted the north Pacific western-boundary deep circulation since the late Miocene. Here, we combine Nd isotope records in the north Pacific and a newly developed water-mass proxy (amorphous Fe hydroxide content, AFHs) from the western Pacific to investigate deep-current evolution since the late Miocene. These proxies consistently indicate a significant deep water-mass change in the north Pacific at ∼5 Ma, reflecting shoaling of the Panama seaway that curtailed intermediate and deep-water exchange between the East Equator Pacific and Atlantic. Although intensification of Antarctic bottom water since ∼3.4 Ma (Northern Hemisphere Glaciation) has been widely documented, a decrease in western-boundary currents has occurred since ∼3 Ma. We suggest that this phenomenon is likely due to the increased mixing of south-ward and north-ward deep western-boundary currents in the north Pacific. This water mass mixing may have a significant impact on the western Pacific biogeochemical cycling.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104514"},"PeriodicalIF":4.0,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141769039","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":"Chemical–to–reverse weathering triggered a pronounced positive carbon isotope excursion in a forced regressive to transgressive dolostone succession during the terminal Ediacaran glaciation","authors":"Yan Zhang,&nbsp;Guangyou Zhu,&nbsp;Xi Li,&nbsp;Yifei Ai,&nbsp;Pengzhen Duan,&nbsp;Mengqi Li,&nbsp;Jincheng Liu","doi":"10.1016/j.gloplacha.2024.104521","DOIUrl":"10.1016/j.gloplacha.2024.104521","url":null,"abstract":"<div><p>The terminal Ediacaran (∼551–541 Ma) was a critical period in Earth's history witnessing the coupled evolution of tectonism, climate, marine environment, and biodiversity, during which a global pronounced positive carbon isotope excursion (i.e., EP3) was recorded in marine carbonates. However, there is still a lack of systematic research on its triggering mechanism. Here, we present high-resolution C–Sr–Li isotopic records from a forced regressive to transgressive microbialite-dominated dolostone succession in the Xigou section of Aksu, northwestern Tarim Basin, aiming to reflect coeval hydrogenous (i.e., seawater-sourced) signals. The forced regressive succession shows distinct positive δ¹³C_carb, δ¹³C_org, and ⁸⁷Sr/⁸⁶Sr_carb excursions, and negative δ⁷Li_carb excursions, reflecting increased terrestrial flux into the ocean and enhanced chemical weathering, which caused an increase in primary productivity and ¹²C-enriched organic carbon burial, as well as incremental inorganic carbon isotope of shallow seawater. The intense continental weathering in this succession is mainly attributed to sea-level fall under the combined control of the Gondwana assemblage and the Luoquan glaciation. The overlying transgressive succession presents relatively stable high δ¹³C_carb, low ⁸⁷Sr/⁸⁶Sr_carb, and positive δ⁷Li_carb excursions, implying the weakened continental weathering, which is probably due to sea-level rise as Luoquan glaciers began to partially melt, and the dominance of reverse weathering. During the early stage of transgression, upwelling transported deep marine nutrients to the photic zone, allowing the high primary productivity of shallow water to sustain for a long time, resulting in the continuous burial of organic carbon with the mass formation of clay minerals and stable high δ¹³C_carb values. Subsequently, as reverse weathering continues, primary productivity decreases, shallow marine oxygen levels decline, and inorganic carbon isotopes gradually fall. This study demonstrates the great potential of Precambrian dolostones as archives of coeval seawater Li isotope, and provides an insight into the co-evolution of carbon cycle, marine redox, and Ediacaran biota from Shuram excursion to EP3 event.</p></div>","PeriodicalId":55089,"journal":{"name":"Global and Planetary Change","volume":"240 ","pages":"Article 104521"},"PeriodicalIF":4.0,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141732396","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}