Depositional Characteristics and Environment of Mixing Sediments of Lower Cambrian Suzhong Formation in Aershan Area, Inner Mongolia

Key words: 
• Aershan /
• Lower Cambrian /
• Suzhong Formation /
• Mixing sediments /
• grain size parameter /
• tidal flat

Abstract: Depositional characteristics and environment of the Lower Cambrian Suzhong Formation in Aershan area of Inner Mongolia are analyzed through integrating areal stratum, lithology, section characteristics, and distribution of the grain size. Grain size of the sandstone in the Suzhong Formation presents the following characters: with double or multimodal anisomerous peaks in grain size distribution frequency curves; mainly in positive skewed distribution; numerous but low peak values; poor sorting and most of the grain consists of those of coarse materials. Based on the size parameters, we located in the Sahu diagram and calculated with discriminate function, it is ascertained that the sandstone in the Lower Cambrian Suzhong Formation which lies in Aershan area of Inner Mongolia are deposited in marine delta environment. Nevertheless, most clastic deposits of the Suzhong Formation is macrograin materials with their grain size distribution similar to wave sand of neritic, and with larger suspension population as well; the mixing deposited sandstone and limestone appears lenticular bedding and rhythmic bedding; so we conclude that the sandstone of this area is deposited in the mixed flat of tide dominate delta. The limestone in the area studied mainly are Greyish white sandy limestone, dolomitic limestone, being recrystallized, with honeycombed surface and horizontal bedding, through these, we draw the following conclusion that limestone of the Lower Cambrian Suzhong Formation in Aershan area of Inner Mongolia are deposited in limemud flat.