Diagenetic Modifications and Reservoir Heterogeneity Associated with Magmatic Intrusions in the Devonian Khyber Limestone, Peshawar Basin, NW Pakistan

Figure 6

Petrographic studies of the Khyber Limestone showing various diagenetic phases. (a) Crossed-polarized photomicrograph showing brown color medium to coarse crystalline, dolomite in contact with marble. Note that the Dol. II postdates the marble. (b) Crossed-polarized photomicrograph showing pore-filling dolomite Dol. II in medium- to coarse-grained marble. (c) Cathodoluminescence photomicrograph showing bright red luminescence of dolomite (Dol. II), and marble with dull orange luminescence. (d) Cathodoluminescence photomicrograph showing progressive dedolomitisation is indicated by the change from bright red luminescent dolomite (Dol. II) to dull orange-colored calcite. (e) Crossed-polarized photomicrograph showing intercrystalline porosity (P) in the Dol. II. The crystals of Dol. II are in contact with medium- to coarse-grained marble. (f) Cross-polarized photomicrograph showing calcitization and dissolution porosity (P) in Dol. II.

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