Abstract:
This thesis presents the petrographic and geochemical study of rocks in the
Singal Gah area, Gilgit. Singal Gah area lies within the northern part of Kohistan Island
arc terrane. The study area is occupied by the Chalt volcanic group (CVG) of
Cretaceous age intruded by the Kohistan batholith (KB). Generally, Chalt volcanic
group comprises of tuffs and metavolcanics. Stage I gabbro and stage II diorite and
granodiorite present in the area belongs to the Kohistan batholith, forming an intrusive
contact with the Chalt volcanic group. Petrographic study conducted on the rocks reveal
gabbro, diorite, granodiorite, quartz mica schist, amphibolite and microgranite. These
rocks are partially altered. Sericite, epidote and chlorite are the common alteration
minerals after plagioclase and hornblende. Deformation of rocks is indicated by kinking
and bending in minerals. Geochemical study supports the mafic to intermediate and
felsic composition of rocks in Singal Gah area. The geochemical signature of the rocks
indicates the calc-alkaline affinity of the rocks with some tholeiitic input in the source
of Ghizer Formation and Kohistan batholith due to the partial melting of the subducting
slab and metasomatized mantle, supporting the island arc type settings. Major element
chemistry shows a common primary melt for the rocks of the study area.
