The Distribution and Origin of Carbonate Cements in Deep-Buried Sandstones in the Central Junggar Basin, Northwest China

Figure 5

Photomicrographs showing petrographic features of the Xishanyao Formation sandstones. Most common types of mineralogy variations in sandstone cement, including (a) secondary pores were mainly filled by crystal calcite, major pores were filled by asphalt at the edges, and the photomicrograph is a stained red-epoxy-impregnated thin sections of conventional core samples by plane-polarized light with magnification of 40 (Y6 well at 6,048.59 m); (b) single-crystal rhombus ankerite, the photomicrograph is a stained blue-epoxy-impregnated thin sections of conventional core samples by plane-polarized light with magnification of 200 (Y6 well at 6028.52 m); (c) a few ankerites replace calcites in a red-epoxy-impregnated thin sections of conventional core samples with cross-polarized light with magnification of 100 (Y2 well at 5966.02 m); and (d) a few dolomites replace calcites in a stained red-epoxy-impregnated thin sections of conventional core samples with cross0polarized light with magnification of 200 (Y2 well at 5967.02 m); (e) crystal calcite filled in pores, and crystal postdate quartz overgrowth in a stained blue-epoxy-impregnated thin sections of conventional core samples by cross-polarized light with magnification of 40 (Y1 well at 5876 m); (f) dolomites develop in a stained blue-epoxy-impregnated thin sections of conventional core samples by plane-polarized light with magnification of 100 (Y2 well at 6000.25 m); (g) calcite cements show bright yellow luminescence in cathodoluminescence photomicrograph with magnification of 40 (Y7 well at 6095 m); (h) calcite cements show saffron luminescence and dolomites cements are disphotic in cathodoluminescence photomicrograph with magnification of 40 (Y8 well at 6099.46 m).

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