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. 3. Photographs of cores, common slices and cast thin section of Ma55. (a) Well SD39-62C, 3 202.76 m, gray limestone, core photograph, (b) common slice of the core sample in the left picture, with calcite dyed red by Alizarin Red; (c) Well Su39-62C1, 3 108.90 m, dolomicrite, core photograph, (d) common slice of the core sample in the left picture, the main mineral is micrite dolomite, with a great quantity of salt pseudo-crystals visible; (e) Well Shan196, 3048.10 m, dolarenite, with a great quantity of spherical particles made up of micrite to silt dolomite visible, fine to medium dolomite filling in between the particles, and abundant intergranular pores, cast thin section, (f) the ten times amplified one of (e), with many gypsum pseudo-crystals.