中文摘要：

二叠纪末期发生的显生宙以来最大的生物灭绝事件，使海洋生态系统和陆地生态系统均受到重创，该事件后微生物岩广泛分布于全球正常浅海地区。研究认为，扬子地台在二叠纪末期存在一次海平面降低的事件，造成研究区二叠纪地层与早三叠世微生物岩之间存在沉积间断或剥蚀，并使三叠纪牙形石混入二叠纪末期的沉积物中。二叠一三叠系界线位于微生物岩层的底界；微生物岩形成于早三叠世最早期，相当于Hindeodus parvus带，是早三叠世最早期开始的海侵事件为其提供生长所需的可容纳空间。在lsarcicella staeschei带一l.isarcica带早期再次发生相对海平面降低事件，之后海平面开始快速上升。研究区早三叠世早期的微生物岩以凝块构造发育为特征，具有斑状、层状、枝状和网状凝块构造4种典型中型构造。结合前人的工作，认为微生物群落通过生物沉积和物理沉积作用形成球状体，球状体汇聚形成不同的中型凝块构造。研究扬子地台早三叠世凝块石的确切时代和结构、构造类型特征，为准确恢复生物大灭绝事件前后的环境变迁以及生物演化事件与环境变化的相互作用关系提供重要的证据。

英文摘要：

The greatest mass extinction event of the Phanerozoic severely damaged both terrestrial and marine organisms at the end-Permian. In the aftermath of the mass extinction, the microbial sediments were extensively deposited in a normal shallow marine environment. Based on the lithologic evidence from the strata across the Permian-Triassic Boundary （PTB） at Dawen of Luodian County of southern Guizhou, an extended hiatus at the PTB has been recognized, implying a major fall in the relative sea level at the end of the Permian in the Yangtze Platform. The earliest Griesbachian Hindeodus parvus commonly occurs below the base of the microbialites at the Dawen section, indicating that the onset of the microbialite growth had been at the earliest Triassic along with a rise of sea level and the transgression beginning from the earliest Early Triassic had provided an accommodation for its development. The skeletal packstone above the microbialites contains abundant IsarciceUa staeschei and I. isarcica, implying that a sea level fall occurred during this time piror to a rapid sea-level rise at late time of the I. isarcicai Biozone. Four categories of the thrombolites are distinguished from the lowermost Triassic succession at Dawen： the spotted, the layered, the dendritic, and the reticular structures based on the preferred direction of mesoclots. Mesoclots are interpreted as the products of coccoid-dominated microbial communities. The different types of mesostructures were formed by the amalgamation of mesoclots, which might have been controlled by biotic and/or physical and chemical, oceanic conditions. The age and sedimentology of the microbialites in Yangtze Platform provide a crucial evidence for the reconstruction of paleoenvironmental change after the end-Permian mass extinction bio-event as well as the synergetic evolution of organisms and environments.