Fig. 8

Photomicrographs of Nukhul sandstones showing: (a) Quartz arenite, detrital quartz and feldspar grains cemented by very coarsely crystalline anhydrite and micro to very finely crystalline dolomite (Note, dolomite cement engulfs feldspar overgrowth and engulfed by anhydrite cement, thus postdate feldspar overgrowth and predate anhydrite cement). (b) Quartz arenite, some of quartz grains show multiple deformation fractures, and quartz overgrowths engulfed by dolomite cement (Note, leached dolomite cement, and k-feldspar overgrowths). (c) Sublithic arenite, quartz grains are fine to medium -grained, sub-rounded to subangular and cemented with sparry calcite cement. (d) Lithic arenite, medium to coarse lithic fragments and glauconite are scattered in calcite cement (Note, detrital quartz coated with iron oxide cement that engulfed by calcite cement, thus predate calcite cement). (e) Sublithic arenite, very poorly sorted sandstone with a patchy detrital clay matrix replaced by dolomicrite cement, (Note, the well-rounded fragment of bone). (f) Quartz arenite, dissolution of microcrystalline dolomite (Note, point- long and concave-convex contacts, anhydrite cement and quartz overgrowth).