【摘要】 PTB全球最大生物灭绝事件后,早三叠世被认为是微生物发育繁殖的黄金时期,浅水环境是微生物活动及微生物岩形成的最有利环境。借助高分辨率扫描电镜和能谱分析,在川东北地区开江—梁平海槽西侧下三叠统飞仙关组浅水碳酸盐岩台地边缘的鲕粒灰岩中发现了三种微生物矿化组构:空腔状微生物矿化组构、显微瘤状微生物矿化组构和纤状微生物矿化组构;通过沉积学、岩石学及地球化学的综合分析,认为显微瘤状微生物矿化组构是微生物新陈代谢时形成的纳米球状云质颗粒,纤状微生物矿化组构是微生物的胞外聚合物,而空腔状微生物矿化组构则属于微生物个体。这些微生物矿化组构的发现,为早三叠世微生物大爆发提供了一定的直观证据;推测大量的微生物活动是早三叠世碳酸盐快速沉积现象的直接诱因,并导致于二叠纪末发育的克拉通内裂陷——开江—梁平海槽在早三叠世被快速填平。更多还原

【Abstract】 After the PTB’s biggest extinction in the world, the Lower Triassic is considered to be the golden era of microbial growth and reproduction. A shallow-water environment is the most favorable for microbial activity and microbial rock formation. Spectral analysis of high-resolution scanning electron microscopy and energy showed three types of microbial mineralized fabric in oolitic limestone, which is the origin of a shallow-water carbonate platform margin on the western side of the Kaijiang-Liangping Trough. These are: cavity-shaped mineralized fabric; micro-nodule-shaped mineralized fabric; and arrow-shaped mineralized fabric. Following comprehensive sedimentological, petrological and geochemical analyses, it is considered that micro-nodule-shaped mineralized fabric consists of dolomitic nanospheroids formed by microbial metabolism. The arrow-shaped mineralized fabric is made up of extracellular polymeric substances(EPS). Cavity-shaped mineralized fabric are microorganism individuals. In addition, a large number of micropores on the surface of calcite crystals were found to be caused by microbial dissolution. The discovery of these microbial mineralized fabrics provides direct evidence of a microbial outbreak in the Lower Triassic. It is assumed that microbial activity is a direct cause of the rapid carbonate deposition phenomenon of the Lower Triassic which led to the rapid Lower Triassic infilling of the Late Permian intracratonic rift in the Kaijiang-Liangping Trough.更多还原