Figure 8

Optical thin sections and SEM images showing (a) directional arrangement of framework grains caused by mechanical compaction, approximately in the direction shown by the blue arrow, well H4, 2530.5 m, PPL; (b) deformed rock fragment, probably micas, well H3, 2560.8 m, SEM; (c) authigenic quartz cements adjacent to dissolved feldspar with obvious intragranular pores (pointed by a green arrow), well H2, 2536.6 m, SEM; (d) vermiform kaolinite accompanied by the coprecipitation of calcite in the primary residual intergranular pores, well H3, 2702.8 m, SEM; (e) fibrous illite, partially converting into smectite, intercrystalline micropores are rare, well H4, 2720.5 m, SEM; (f) Calcite cements completely occlude the intergranular pores, well H1, 2533.8 m, cross-polarized light; (g) Fibrous dawsonite, well H1, 2579.9 m, SEM; (h) framboidal aggregates of pyrite accompanied by illite and quartz overgrowth, well H2, 2582.5 m, SEM; (i) flaky chlorite growth on the edge of the quartz overgrowth, well H2, 2979 m, SEM; (j) dissolution of feldspar,co-precipitation of authigenic quartz, kaolinite and illite were observed within pore from feldspar dissolution. Note the illite cements were formed from illization of kaolinite, well H2, 2582.5 m, SEM. Qa = authigenic quartz, Qo = overgrowth, Cal = calcite, Daw = dawsonite, Mi = mica, F = feldspar, I = illite, K = kaolinite, Py = pyrite, Ch = chlorite, I/S = mixed layers of illite and smectite.