弗拉—法门转折期气候—海洋环境变化及生物危机成因探讨  

Paleoclimatic and Paleo-Oceanic Environment Evolution in the Frasnian-Famennian Transition:Potential causes of the biotic crisis

作　　者：张力钰 陈代钊[3] 刘康 ZHANG LiYu;CHEN DaiZhao;LIU Kang(Wuxi Research Institute of Petroleum Geology,Petroleum Exploration and Production Research Institute,SINOPEC,Wuxi,Jiangsu 214126,China;SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms,Wuxi,Jiangsu 214126,China;Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Key Laboratory of Petroleum Geochemistry,Research Institute of Petroleum Exploration and Development,CNPC,Beijing 100083,China)

机构地区：[1]中国石化石油勘探开发研究院,无锡石油地质研究所,江苏无锡214126 [2]中国石化油气成藏重点实验室,江苏无锡214126 [3]中国科学院地质与地球物理研究所,新生代地质与环境院重点实验室,北京100029 [4]中国石油勘探开发研究院,油气地球化学重点实验室,北京100083

出　　处：《沉积学报》2024年第3期723-737,I0001,共16页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(U19B6003,42330203)。

摘　　要：【目的】晚泥盆世弗拉—法门(Frasnian-Famennian,F-F)转折期是地质历史的一个关键时期,海洋生态系统发生了重大变化并造成了低纬度地区浅海底栖生物的大量灭绝。关于该时期的古气候、古海洋环境变化以及生物灭绝的成因机制研究目前已取得一定的进展,但仍然存在争议且各环境要素之间的相互作用尚不明确。【方法】在系统梳理F-F转折期古气候、古海洋环境变化研究现状的基础上,结合华南的研究实例探讨了F-F转折期的古海洋缺氧模式。【结果与结论】F-F转折期,气候在变冷的趋势下出现多次快速的暖—冷交替;缺氧范围和程度各地表现不一,但主要集中在低纬度浅海地区上Kellwasser层附近。因此,F-F生物危机并不是单一因素造成的。频繁、短暂的火山活动引起大陆风化作用增强,一方面导致了气候快速的暖—冷交替,另一方面促进了陆地向海洋中输入营养物质造成浅海的富营养化和缺氧。各个环境因素相互制约/影响对低纬度浅海地区生命造成极大的环境压力,最终导致了F-F生物危机。[Objective]The Late Devonian Frasnian-Famennian(F-F)transition is a critical time interval in geological history.This period saw major simultaneous marine ecological system changes that led to one of the Big Five mass extinctions in the Phanerozoic.The F-F event(also referred to as the Kellwasser event)was characterized by severe losses of low-latitude shallow-water benthic faunas,notably reef-dwelling coral and stromatoporoids.High-latitude,deep-sea and terrestrial faunas were the least affected.Various separate or combined hypotheses have been proposed as the causes of this mass extinction(sea-level change,marine anoxia,climate change,volcanic/hydrothermal activities,and bolide impact).Of these,climate change and marine anoxia have been the most intensively researched and discussed hypotheses based on the Web of Science in recent years.However,some controversies remain,and the interactions of certain factors are still unclear.[Methods]This study systematically reviews available reports on the paleoclimatic and paleo-oceanic changes during the F-F transition and discusses the anoxic model during this critical period,based on related case studies in southern China.[Results and Conclusions]Conodont oxygen and strontium isotopes,as well as the carbon isotope records for carbonates,collectively suggest a cold climate during the F-F transition interval,with several rapid warming-cooling fluctuations.Conodont oxygen isotopes suggest that the sea-sur face temperature(SST)dropped by 5℃-8℃.Strontium isotopes also imply that the temperature fluctuations were due to frequent,short-duration volcanism.Palynological data and carbonate platform exposure/karstification are also suggestive of coeval climate cooling.Additionally,marine anoxia has been extensively hypothesized as a possible killing mechanism in the F-F mass extinction,based initially on the presence of bituminous limestones(or black shales),named the lower and upper Kellwasser horizons.Studies of pyrite framboids,biomarker compounds,trace elements,isotopes of

关 键 词：弗拉—法门转折期 古气候 古海洋氧化还原状态 生物危机 

分 类 号：P512.2[天文地球—地质学]