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

Figure 5

Petrographic studies of the Khyber Limestone showing various diagenetic phases. (a) Crossed-polarized photomicrograph of the coralline limestone (wacke- to packstone) containing fracture-filling dolomite (Dol. I) shown by blue arrow (b) Medium to coarse crystalline (Dol. I) exhibiting undulose extinction typical of saddle nature; clay minerals filling the intercrystalline pore spaces shown by white arrow. (c, d) Cathodoluminescence (CL) photomicrograph showing dull luminescent dolomite (Dol. I); pore-filling detrital clays are nonluminescent (arrow). (e) Partial replacement of coralline limestone with coarse-grained marble in the upper part while the limestone is in the lower part. (f) Partial to complete replacement of coarse crystalline, nonplanar dolomite by marble.

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