华南二叠纪—三叠纪之交微生物岩的古地理背景及沉积微相特征  

Palaeogeography and microfacies characteristics of microbialites across the Permian-Triassic boundary in South China

作　　者：何磊[1] 王永标[1] 杨浩[1] 廖卫[1] 翁泽婷[1] 

机构地区：[1]中国地质大学(武汉)生物地质与环境地质教育部重点实验室,湖北武汉430074

出　　处：《古地理学报》2010年第2期151-163,共13页Journal of Palaeogeography：Chinese Edition

基　　金：国家自然科学基金项目(编号:40730209;40572002);中国石油化工股份有限公司海相油气勘探前瞻性项目"海相优质烃源岩形成的地球生物学过程"(编号:G0800-06-ZS-319)资助

摘　　要：二叠纪末生物大灭绝后,在华南地区碳酸盐岩台地上普遍形成一套微生物岩。微生物岩所代表的是一种以蓝细菌和其他底栖生物为主体的独特的生态系。蓝细菌作为生产者是该生态系的基础,种类单调的小型腹足类和介形虫等广盐性多细胞生物和灾后残存的有孔虫则是该生态系中的主要消费者。根据所处的古地理位置不同,华南微生物岩的分布可分为3个主要地区,即上扬子地区、中下扬子地区及南盘江地区。上述3个地区微生物岩分别产出在生物礁顶、一般碳酸盐岩台地边缘和孤立碳酸盐岩台地环境,且不同地区微生物岩所在剖面的沉积序列也存在差异。根据不同地区微生物岩在宏观沉积构造和碳酸盐岩微相组合上的差异,可进一步划分为层纹状微生物岩、叠层石微生物岩、花斑状微生物岩、树枝状微生物岩及穹窿状微生物岩。不同微相类型的微生物岩在沉积水深、蓝细菌化石、底栖群落组合上仍存在差异,其中树枝状和穹窿状微生物岩沉积时所处水深最小,花斑状微生物岩和层纹状微生物岩沉积时所处水深可能相对较大。对不同地区微生物岩的研究为认识二叠纪末全球事件期间海洋环境的多样性和演化过程提供了重要的信息。Microbialites end-Permian mass extinction. were widely distributed Microbialites represent and other benthonic organisms. Cyanobacteria played on the carbonate platform in South China after the a particular ecosystem, composing of cyanobacteria an important role as the producers in the ecosystem, while the euryhalinous and benthic faunas were the main customers, including low-diversity microgastropods, ostracods, and disaster foraminifers. Based on the different palaeogeographic location, microbialites in South China can be divided into three districts： the Upper Yangtze platform, the Middle and Lower Yangtze platform and the Nanpanjiang Basin. Microbialites in the above areas were produced on the top of reef facies, carbonate platform and isolated carbonate platforms respectively. Section sequences where microbialites were developed are different from place to place. Microbialites can be subdivided into different types based on macro sedimentary fabrics and carbonate microfacies, including the laminated microbialite, stro- matolite, clotted microbialite, digitate and domed microbialites. Different types of microbialites were formed in different water depths, containing different assemblages of cyanobacteria and benthic animal fau- na. Our research indicates that the digitate or domed microbialites should have been deposited in the most shallow water environment and the laminated or clotted microbialite probably in relatively deep water conditions. Study of the sedimentary structures and carbonate microfacies of microbialites in different areas in South China will provide important information about the diversity and evolution of the oceanic environment during the end-Permian global event.

关 键 词：微生物岩 碳酸盐岩微相 古地理 二叠纪-三叠纪 华南 

分 类 号：Q911.5[天文地球—古生物学与地层学]