Characteristics and Paleoenvironmental Significance of Microbially Induced Sedimentary Structures(MISSs) in Terrestrial P-T Boundary in Jiyuan, Western Henan Province

Key words: 
• microbially induced sedimentary structures /
• the end-Permian mass extinction /
• terrestrial ecosystems /
• Jiyuan

Abstract: We have firstly reported the presence of eight kinds of microbially induced sedimentary structures (MISSs) or sedimentary surface textures, including growth ridges, growth postulas, curved desiccation cracks, spindle-shaped cracks, "Manchuriophycus" structures, dendritic desiccation cracks, polygonal desiccation cracks and desiccation cracks from the terrestrial upper Permian Sunjiagou Formation and lower Triassic Liujiagou Formation in Jiyuan western Henan. Large U ridges, oriented sand quartz, mica grains and thin clayey laminae arranged parallel to bedding plane are the main features visible under the microscope. A series of evidence indicate that the Jiyuan MISSs are of biogenic origin. Compared with MISSs of the Mesoproterozoic Yunmengshan Formation in Lushan, the Mesoproterozoic Changchougou Formation in Licheng, Lower Triassic Liujiagou Formation in Yiyang and Liulin, we concluded that microbially induced sedimentary structures has special taphonomic characteristics and was controlled by the end-Permian mass extinction, sedimentary environments and climate factor in Jiyuan. MISSs of Jiyuan stands for terrestrial ecosystems following the end-Permian mass extinction with rich microbial community, scarce metazoan, poor plant, hot weather and serious soil erosion.