Microbial Induced Sedimentary Structures (MISS) of the Mesoproterozoic Ruyang Group in western Henan Province

Abstract：Microbial Induced Sedimentary structures (MISS) in sandstone beds are abundant in the Palaeoproterozoic Ruyang Group, western Henan Province. In the past, the MISS were regarded as the oldest trace fossils of metazoa in Precambrian. This paper has studied the characteristics of MISS’s macroscopic morphologies, structures and microfabrics in the Palaeoproterozoic Ruyang Group of western Henan Province. The results suggest that there are four types of MISS, i.e., ‘polygonal reticulation cracks’, ‘spindle cracks’, ‘bird foot cracks’ and ‘Manchuriophycus’. An observation of the microbial induced sedimentary structures in the Palaeoproterozoic Ruyang Group reveals the occurrence of photoautotrophic microbial mats in sandstone beds from the Precambrian up till now. It is very useful not only to understanding of some sedimentary structures induced by living microbial mats and reconfirming the structures regarded in the past as the oldest trace fossils of metazoa in Precambrian but also to the reconstruction of the sedimentary environment in Precambrian.