Fracture, Dissolution, and Cementation Events in Ordovician Carbonate Reservoirs, Tarim Basin, NW China

Figure 5

Hand specimen of middle Yijianfang Formation (a), top of the Yijianfang Formation (b), and Tumuxiuke Formation (c) showing rounded and elongated mottle fabrics (channels) filled with calcite sediment Cs0. (d) Optical-CL photomicrograph of packstone showing subrounded mottle fabrics filled with calcite sediment Cs0a subsequently cemented by Cc2. (e, f) SEM images showing carbonate-rich detritus Cs0a within mottle fabrics. Most of the interparticle porosity is filled with illite and/or bitumen (f). (g) Plane light optical photomicrograph of wackestone showing vertical channels filled with calcite sediment Cs0b. (h, i) SEM images showing carbonate-rich detritus Cs0b within vertical channels. Most of the interparticle porosity is filled with illite, kaolinite, and/or bitumen (i).

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