PETROGRAPHIC AND SEM-EDX CHARACTERIZATION OF MAFIC-FELSIC PLUTONIC ROCKS OF WASHAPI KAUR WESTERN RASKOH ARC, PAKISTAN

Abstract

The Washapi Kaur plutonic rocks is located at the western part of the Ras-Koh arc, Pakistan, and intruded in the Cretaceous to Paleocene rock sequences. This complex consists of two main magma series, mafic to intermediate, forming small gabbro and diorite intrusions and felsic comprising granitic rock units. Gabbro consists of clinopyroxene, plagioclase, amphibole, and biotite and displays in-equigranular poikilitic texture. Diorites present porphyritic texture and mainly composed of plagioclase, K-feldspar, amphibole, quartz, and biotite with minor constituents of clinopyroxene. Granites are comprised of quartz, K-feldspar, plagioclase, biotite and muscovite. The field features, petrographic and SEM (Scanning Electron Microscopy) suggest that the magmatic activity in the Washapi Kaur formed as the initial mantle-melt magma derived from mafic to the intermediate source. Later, the melt interacted with slab-derived hydrous fluids in a continental arc setting.