Origin and characteristics of grain dolomite of Ordovician Ma5 5 Member in the northwest of Ordos Basin, NW China

ZHANG Xi,ZHANG Tingshan,LEI Bianjun,ZHANG Jingxuan,ZHANG Ji,ZHAO Zhongjun,YONG Jinjie

Fig. 4. Core photographs, common slices, cast thin sections and Scanning Electron Microscope Photographs of grain dolomite. (a) Well S203, 3 921.25 m, grain dolomite, core photographs; (b) Well SH36, 3 113.72 m, grain dolomite, red cast thin section; (c) Well Z28, 3 262.11 m, grain dolomite, with intergranular pores near cracks, common slice; (d) Local part of c amplified ten times; (e) Well SD37-58, 3 118.00 m, grain dolomite, fine to medium dolomite; (f) Well SD39-62c1, 3 116.82 m, grain dolomite, cathodoluminescence photographs; (g) Well Z28, 3 262.11 m, grain dolomite, with bigger crystals near fractured dissolution pores, Scanning Electron Microscope; (h) Well Z28, 3 262.11 m, grain dolomite, with larger dolomite crystals near the crack, Scanning Electron Microscope.