Petrographic Studies of the Vihowa Formation, Sulaiman Range, Pakistan: Implications for Provenance

The Vihowa Formation of late to early Miocene is investigated for mineral composition and petrographic characteristics to understand the provenance, diagenesis and depositional environments. Ten representative sandstone samples were collected from various lithological units for petrographic studies. Petrographic results show that the quartz is a major constituent; while the accessory minerals are chlorite, chamosite, palagonite, sphalerite, staurolite, aragonite, hypersthene, glaucophane, monazite, kyanite, epidote, olivine, rutile, ilmenite, hematite, magnetite, zircon, tourmaline and garnet. The tourmaline and rutile showing an igneous source however, the presence of epidote, staurolite and garnet expresses a metamorphic source for studied sandstones. The sandstone is medium to coarse grained having grains dominantly from the meta-sedimentary rocks whereas minor amount of grains from igneous rocks is also observed. Monocrystalline quartz is present in sands derived either from gneiss or granitic rocks, but polycrystalline quartz are from slate and schist. The inclusion of mica and garnet within quartz is observed which indicates a metamorphic source. On the QFL triangular diagram the sandstone of Vihowa Formation is mainly sub-lithic arenite and partly quartz arenite. The Qm-P-K plots indicate that feldspar and quartz are from granitic rocks along with small amount from metamorphic and volcanic rocks. The provenance of sandstone indicates that sediments were mostly deposited by transitional recycled orogeny and mixed magmatic subduction complex.