Reconstruction of Ocean Redox Environment During the Late Permian Wuchiapingian,Northern Margin of Upper Yangtze
[Objective]Although the end-Guadalupian extinction is not as well known as the end-Permian extinc-tion,it is regarded as a critical event that resulted in considerable biodiversity loss and significant disruptions to eco-systems.Following the End-Guadalupian extinction,global biodiversity was progressively restored during the Late Permian.Despite this recovery,the intricate relationship between biological resurgence during this era and the redox conditions of palaeo-oceans is still not fully understood.[Methods]The Wuchiaping Formation located in the Shangsi section of the northern margin of the Yangtze Block with high-resolution time frame constraints was selected as the re-search object.Petrological and sedimentary geochemical studies were employed to reconstruct the marine redox envi-ronment associated with the Wuchiaping Formation in the Late Permian.By examining the rock composition and geo-chemical signatures of the rock samples,we established key indicators of redox conditions(Ce*;Ce anomaly).Addi-tionally,we selected several indicators,including Th,Sc,Y/Ho,and Mn/Sr,to assess whether the redox indicator was influenced by non-redox factors.[Results]The collected global carbon isotope from the Wuchiapingian of Late Permian consistently exhibited a significant positive bias in the early Wuchiapingian,followed by a notable negative bias in the middle Wuchiapingian changes,indicating that this carbon cycle disturbance event had a worldwide im-pact.Moreover,this transformation corresponds to changes in seawater redox conditions,showing a close correlation between carbon cycle disturbance events and alteration in redox environments.Through comparison of the stratigraph-ic framework,the disturbance was found to align with the waxing and waning of P4 glaciation.Based on the systemat-ic changes in the Ce anomaly curve of carbonate rocks,the evolution of marine redox conditions during the Wuchiapingian of Late Permian can be divided into three stages,reflecting three distinct global shifts in climate and environmental conditions.The gradual resurgence of early organisms led to an increase in primary productivity and photosynthesis,and the cooler climate was conducive to ocean circulation and facilitated oxygen exchange,resulting in an oxygen-poor environment.As the climate gradually warmed and the Late Paleozoic ice age ended,the situation began to shift dramatically.The weakening of ocean ventilation,caused by alterations in temperature gradients and circulation patterns,coupled with rising sea levels contributed to the expansion of the minimum oxygen zone,conse-quently transforming the ocean into an anoxic environment.This shift had profound implications for marine life and the overall health of ocean ecosystems,setting the stage for significant biological upheaval in the ensuing geological periods.[Conclusions]The study developed a redox model of the shallow marine environment during the Wuchiapin-gian,providing insight into the interactions between various environmental factors.It highlights a significant connec-tion between the oceanic hypoxia event and the simultaneous biological and geological tectonic activities occurring.By examining these relationships,the research enhances our understanding of how environmental factors influenced marine life and sedimentary processes during this critical period in Earth history.
Late PermianCe anomalyocean anoxiabiological recoveryUpper Yangtze
雍茹男、孙诗、陈安清、侯明才、李夔洲、李乾、黄光辉、李雯、解昊、陈洪德
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油气藏地质及开发工程全国重点实验室,成都理工大学,成都 610059
自然资源部深时地理环境重建与应用重点实验室,成都理工大学,成都 610059
西南科技大学环境与资源学院,四川 绵阳 621010
School of Earth Environment,University of Leeds,Leeds UK LS2 9JT
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