Origin of the penecontemporaneous sucrosic dolomite in the Permian Qixia Formation, northwestern Sichuan Basin, SW China

LU Feifan,TAN Xiucheng,ZHONG Yuan,LUO Bing,ZHANG Benjian,ZHANG Ya,LI Minglong,XIAO Di,WANG Xiaofang,ZENG Wei

Fig. 3. Macroscopic and microcosmic features of Kfd in Qixia Formation of northwestern Sichuan Basin. (a) Well D6, 7747.25 m, Qi-2 Member, core sample, in-suit breccia resulted from bedrock cutting by karrens; (b) Well D6, 7747.25 m, Qi-2 Member, grain dolomite fragments dissociated by karstification, obvious bay-like dissolution edge of some grains, PPL; (c) Well D6, 7736.00 m, Qi-2 Member, core sample, fillings and breccia in karst system; (d) Well D6, 7757.54 m, Qi-1 Member, core sample, Kfd and bedrock, bedrock breccia mixing with dolomitic filling; (e) Well D6, 7336.00 m, Qi-2 Member, mixed mud, organic matter, rounding breccia and dolomite fragments filling in the karst system (PPL); (f) Well D2, 2418.54 m, Qi-2 Member, core sample, dolomite filling in the karst system; (g) Well D2, 2418.54 m, Qi-2 Member, autochthonous-semiautochthonous dolomite and acid insoluble material filling in the karren, the dolomite occasionally has a turbid core and bright rim structure, the surrounding rock is Md2 (PPL); (h) Well D2, 2418.54 m, Qi-2 Member, the core of Kfd gives off dark red light, the edge of dolomite with bright red light, the surrounding rock with dark red light in cathodoluminescence test.