Abstract:
Detailed petrographic studies have been carried out of the Lower Cretaceous
Lumshiwal Formation from Thandiani section, Hazara Basin. Petrography of sandstone
gives valuable details about its formation, miniature texture, diagenetic highlights,
provenance of sediments and their development. The sandstone from Lumshiwal Formation
is fundamentally "quartz arenite" having white color. It is exceptionally hard and compact
because of the richness and close interlocking of quartz grains. In addition to quartz, the
sandstone from Lumshiwal Formation contains feldspars, rock fragments, glauconite,
monazite, tourmaline, zircon, muscovite, chert and rarely apatite. The sandstone of the
Lumshiwal Formation exhibits mineralogical maturity. It seems to be sub-mature in terms
of textural maturity. This is indicated by its moderate degree of sorting. It has
mineralogically mature character due to very high modal proportion of quartz as compared
to feldspar. The sandstone from Lumshiwal Formation is very much solidified, hard and
compact. Different types of cement for example silica, glauconitic cement and ferruginous
cement is present in the sandstone unit from Lumshiwal Formation. Shallow marine
environment is exhibited by the sandstone unit of the Lumshiwal Formation due to high
abundance of quartz and presence of glauconite mineral.
