Distribution and depositional model of microbial carbonates in the Ordovician middle assemblage, Ordos Basin, NW China

WEI Liubin,ZHAO Junxing,SU Zhongtang,WEI Xinshan,REN Junfeng,HUANG Zhengliang,WU Chunying

Fig. 4. Micro sedimentary structure of microbial carbonates in the Ordovician middle assemblage in mid-east of Ordos Basin. (a) Laminar stromatolite dolomite with fenster pores, 3765.33 m, Ma56, Well Tao 78, blue cast, single polarized; (b) Columnar stromatolite dolomite with fenster pores filled with anhydrite, 2548.24 m, Ma55, Well Mi 75, single polarized; (c) Cake-shaped bacterial carbonate (yellow arrow), 3642.40 m, Ma56, Well Tao 113, single polarized; (d) Stromatolite dolomite with Hydatid bacterial carbonate (yellow arrow), 3437.89 m, Ma57, Well Tao 112, single polarized; (e) Stromatolite dolomite with Spirulina calcifying cyanobacterial carbonate (yellow arrow), dissolved pores, 3378.72 m, Ma56, Well Tao 112, blue cast, single polarized; (f) Oncolite limestone, 3309.97 m, Ma55, Well Tao 112, single polarized.