藏南Kioto碳酸盐台地对早侏罗世普林斯巴晚期碳循环扰动的沉积和生物响应  

Sedimentary and Biotic Response of Kioto Carbonate Platform to the Late Pliensbachian(Early Jurassic)Carbon-Isotope Perturbations in Southern Tibet

作　　者：翁晓爱 姜守一 韩中 胡修棉[4] 晏雄 WENG XiaoAi;JIANG ShouYi;HAN Zhong;HU XiuMian;YAN Xiong(Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;School of Earth Sciences,China University of Geosciences(Wuhan),Wuhan 430074,China;State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu 610059,China;State Key Laboratory for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China;Chengdu Center,China Geological Survey,Chengdu 610059,China)

机构地区：[1]成都理工大学沉积地质研究院,成都610059 [2]中国地质大学(武汉)地球科学学院,武汉430074 [3]成都理工大学油气藏地质及开发工程国家重点实验室,成都610059 [4]南京大学地球科学与工程学院内生金属矿床成矿机制研究全国重点实验室,南京210023 [5]中国地质调查局成都地质调查中心,成都610059

出　　处：《沉积学报》2024年第2期415-433,共19页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42002121,41888101,42272116);国际地球科学计划项目(IGCP739)。

摘　　要：【目的】早侏罗世发生了多次重要的碳循环扰动,并伴随气候和环境的重大变化。然而,现有的研究主要集中于西特提斯和欧洲北部,对东特提斯碳循环扰动事件以及定量探究事件对生物影响的相关报道较少。【方法】利用东特提斯藏南Kioto碳酸盐台地普林斯巴晚期—托阿尔(最早)期的生物地层学(大型底栖有孔虫)、沉积学和碳同位素(δ^(13)C)地层学,探讨碳循环扰动以及相应的气候环境变化对该地区的碳酸盐台地生物演化过程影响。【结果】普林斯巴晚期—托阿尔(最早)期大型底栖有孔虫生物地层显示有3个带:Bosniella oenensis-Cyclorbitosella tibetica(?)、Streptocyclammina liasica和Siphovalvulina sp.A。在生物地层基础上,我们识别出以δ^(13)C正偏移为特征的普林斯巴晚期margaritatus菊石带事件(margaritatus zone event,ME)和以δ^(13)C负偏移为特征的margaritatus-spinatum界线事件(margaritatus-spinatum boundary event,MSBE)。【结论】在ME期间,生屑颗粒含量呈增长趋势、大型底栖有孔虫的种属和数量保持较高的水平以及Lithiotis Fauna出现并扩散,这可能表明有机质的大量埋藏消耗了辛涅缪尔晚期—普林斯巴早期产生的大量CO_(2),从而创造了更适合生物生存的海洋环境条件。在MSBE期间,生屑颗粒含量以及Lithiotis Fauna丰度和长度整体呈下降趋势,并且部分大型底栖有孔虫的灭绝,表明该时期存在着生物危机,可能与海平面下降有关。虽然Lithiotis Fauna存在大小和出现的频率变化,但不可否认的是,Lithiotis Fauna在普林斯巴期整个特提斯浅水碳酸盐台地蓬勃发展,直到T-OAE时期才完全破坏其生存条件。[Objective]During the Early Jurassic,multiple significant perturbations of the carbon-cycle occurred that coincided with abrupt and extreme changes in climate and environment.However,existing research has primarily focused on the western Tethys and northern Europe,with limited attention given to carbon cycle disturbances in the eastern Tethys and the quantitative assessment of their impact on biota.[Methods]This study examined the biological(larger benthic foraminifera),sedimentological,and carbon-isotope(δ^(13)C)stratigraphy from the southern Tibetan Kioto Platform formed in the southeastern Tethys during the Late PliensbachianEarliest Toarcian interval to investigate the influence of carbon-cycle perturbations and corresponding climatic and environmental variations on the evolution of carbonate-platform biota in the region.In addition,this study quantitatively analyzed the content of carbonate skeletal grains,the number and species changes of lager benthic foraminifera,and the distribution of Lithiotis Fauna to explore the impact of these events on biota.[Results]Three foraminiferal zones were recognized:Pliensbachian Bosniella oenensisCyclorbitosella tibetica(?)and Streptocyclammina liasica,as well as the Earliest Toarcian Siphovalvulina sp.A.According to the sedimentary structure and the quantitative analysis of grains composition and content,this study identified nine carbonate microfacies(MF)from the Pupuga Formation in the Dongqiu section.These microfacies included mudstone(MF1),dolomitic peloidal wackestone(MF2),bioclastic peloidal packstone(MF3),bioclastic wackestone/packstone(MF4),intraclastic packstonegrainstone(MF5),lump grainstone(MF6),Lithiotis rudstone(MF7),bioclastic grainstone(MF8),and oolitic grainstone(MF9).The sedimentary microfacies and microfacies assemblages reveal that the Pupuga Formation in the Dongqiu section represented the shallowwater carbonate platform deposit,characterized by minimal influence from terrigenous input.Furthermore,temporal variation in microfacies demonstrated that t

关 键 词：普林斯巴期 碳酸盐台地 碳酸盐岩微相 碳同位素扰动 生物危机 

分 类 号：P512.2[天文地球—地质学]