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二叠纪-三叠纪之交地球表层系统的多幕式变化:分子地球生物学记录

ISSN号：0001-6616
期刊名称：古生物学报
时间：0
页码：45-47
语言：中文
分类：P534.51[天文地球—古生物学与地层学;天文地球—地质学] X43[环境科学与工程—灾害防治]
作者机构：[1]中国地质大学生物地质与环境地质教育部重点实验室,武汉430074, [2]中国科学院南京地质古生物研究所,南京210008, [3]中国石油大学,北京昌平102249
相关基金：国家自然科学基金（Nos.40525008,40621002）和111项目（B08030）联合资助.致谢二叠纪-三叠纪之交生物危机的多幕式观点是中国地质大学（武汉）古生物学与地层学学科组在长期的实际工作中形成的集体成果,在此,对所有参与工作的同行表示衷心感谢.
相关项目：沉积学（含现代沉积、沉积地球化学、有机地球化学）

关键词：分子化石, 生物标志化合物, 微生物, 动物集群灭绝, Molecular fossils, biomarkers, microbes, faunal mass extinction

中文摘要：

以浙江长兴煤山二叠系-三叠系界线剖面为重点,总结了近年来在分子和同位素方面的重要进展。2-甲基藿烷指数反映了蓝细菌繁盛集中在二叠系-三叠系界线附近约1Ma的时间内,对应于第26—37层,并主要以两幕形式出现。第一幕在第26层,第二幕在第29—37层（由多个峰值组成）。海洋有孔虫、腕足类和牙形石等动物的灭绝也主要表现为两幕,分别对应于煤山剖面第25层和第28层。碳酸盐碳同位素出现两幕负偏,分别对应于第24—26层和第29—37层,可以在特提斯海域进行对比。绿硫细菌分子标志化合物指示的海水透光层富H2S事件集中在两个层位,分别出现在第21—24层（由多个峰值组成）和第11—14层,但第一幕（第11—14层）距离动物大规模灭绝时间约1Ma之久。陆地生态系统的崩溃和陆地风化作用的加强也主要表现为双幕式。二叠纪-三叠纪之交生物危机和环境变化均以幕式表现出来,特别是双幕式,反映了当时地球表层系统的变化表现出两个重要特征,即不稳定性和长期性。值得注意的是,奥陶纪-志留纪之交、晚泥盆世弗拉期-法门期之交、二叠纪-三叠纪之交、三叠纪-侏罗纪之交这4次生物大灭绝均表现出双幕式特点,是生物对同一地内事件两种不同状态（如海平面变化中的海退和海进,气候变化中的变暖和变冷等）或者多种地内事件的综合响应,可能是地内事件导致生物危机的一个共同特征,从而区别于地外事件引起的单幕式生物灭绝。

英文摘要：

Achievements in molecular and isotopic organic geochemistry are reviewed based on the work conducted in the Permian-Triassic transitional period of Meishan sections in Zhejiang,China.The 2-methylhopane index indicates cyanobacteria expanded during the faunal mass extinction and spanned a period of 1Ma,corresponding to beds 26—37 at Meishan.Cyanobacterial expansion was found primarily to occur in two episodes,with the second episode from bed 29 to bed 37 featured by multiple maxima.The faunal mass extinction including foraminifera,brachiopod,and conodont is documented to occur in two episodes,corresponding to bed 25 and bed 28,respectively.The biomarkers of green sulfur bacteria,2-alkyl-1,3,4-trimethylbenzenes and isorenieratane,are suggestive of the enhanced euxinia of the photic zone within two intervals,beds 21—24（composed of multiple maxima） and beds 11—14.The euxinia of the photic zone at beds 11—14,which is more than 1Ma prior to the faunal mass extinction,is much more severe than that at beds 21—24 near the biotic crisis.The carbon isotope composition of carbonate rocks is found to show two negative excursions,respectively at beds 24—26 and beds 29—37,which is identifiable and biostratigraphically correlative within the Tethys sea.The collapse of terrestrial ecosystems and the enhanced terrestrial erosion are demonstrated to take place in two episodes.The occurrence of the two episodes of both the biotic and environmental events,in both the land and the sea,indicates the long duration and the strong disturbance of the changes of the Earth surface system during the Permian-Triassic transitional period.It is notable that the biotic crises across the Ordovician-Silurian boundary,the Frasnian-Famenian boundary in Late Devonian,the Permian-Triassic boundary,and the Triassic-Jurassic boundary are all documented to occur in two episodes.The identification of the two episodes of the four Phanerozoic biotic crises is indicative of the intrinsic triggers of the Earth system,rather than the extraterr