Diagenetic Evolution of Marine Carbonate Reservoirs: A Case Study from M5_1-2 Submember of Middle Ordovician Majiagou Formation in SE Ordos Basin, China

Figure 4

Photos of reservoir rock types and fillings in M5_1-2 submember of Majiagou Formation. (a) Crystal dolomite, moldic pores in anhydrite accretions. (b) Fine-powder dolomite, fracture development. (c) Karst breccia dolomite, dissolution pores between breccias. (d) Photomicrograph showing fractures filled with granular calcite and coarse-grained calcite. (e) Optical CL photomicrograph of ferrocalcite is filled in the fracture. (f) Optical CL photomicrograph of ferrodolomite is filled in moldic pores. (g) Plane light optical photomicrograph of moldic pores in anhydrite accretions, completely filled with freshwater dolomite. (h) Plane light optical photomicrograph of moldic pores in anhydrite accretions, completely filled with calcite. (i) Plane light optical photomicrograph of the fracture is filled with saddle dolomite. (j) Optical CL photomicrograph of the fracture is filled with calcite and kaolinite. (k) Plane light optical photomicrograph of gypsum crystals, filling calcite in tabular moldic pores in gypsum. (l) Optical CL photomicrograph of fluorite is filled in the pores.

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