Abstract:

Microbially Induced Sedimentary Structures (MISS) rise from the interaction of benthic microbiota with physical sediment
dynamics. It was the important product and geological record in clastic sediments of microbial community activity. Research on MISS is of great significance for understanding evolution of earth-surface environment, because MISS was widely found in terrigenous fragmentary rock of Precambrian and was occasionally distributed in Phanerozoic. Based on observation, description and genesis of outcrops, the MISS in Lushan area can be divided into three types: Mat growth feature, Mat destruction feature, and Mat decay feature. With the aid of micromorphological observation, we analyzed and discussed morphological feature, geologic structure, components, genesis and sedimentary environment of MISS. Based on microscopic analysis for quartz grain and composition characteristic of MISS, we found that microbial community develop in the relatively high-energy and fine-grained sediments environment. Therefore, we conclude that MISS mainly developed near intertidal zone to supralittoral zone. This research will contribute to the discrimination of the paleocurrent direction, intensity and ionic content, and can also help reconstruct paleoenvironment to a certain extent.

Key words: Meso-Neoproterozoic, MISS, Microbial mats, Microstructure