Microbial Mats and Terrigenous Sedimentation Settings in the Precambrian: The Middle Riphean Bezymyannyi Formation of the Turukhansk Uplift

The Bezymyannyi Formation is a thick (up to 900 m) terrigenous rock complex that formed in the distal part of the ciliciclastic shelf with the storm-influenced sedimentation settings. The barrier belt of coarse-grained sandy sediments divided different-depth zones of the outer and inner shelf that included spacious areas populated by mat-forming communities. Development peculiarities of these communities and their relationship with erosion–flow structures are considered in detail. Microbial mat domains represented transient zones that both determined the internal sedimentation patterns and influenced sediment flows in the entire basin. The model explaining peculiarities of the Precambrian terrigenous sedimentation by the influence of intrabasin factor (wide development of matground microbial communities) is proposed.