DefinePK

Abstract

This paper describes the geology of an area of about 1200 krn2 in the upper Kaghan valley. The area is traversed by Main Mantle Thrust, which juxtaposes the southeastern part of the Kohistan terrane in tectonic contact with the higher Himalayas of the Indian plate. The Indian-plate sequence in the study area comprises a basement of granitic gneisses (both ortho- and paragneisses) followed by the Domel unit (calcareous schists/paragneisses, garnetiferrous marbles, calc silicates and amphibolites) and the Parla Sapat unit (graphitic quartz-mica to garnet staurolite schists). These rocks are in tectonic contact with the mafic-ultramafic rocks of the Sapat complex along the Main Mantle Thrust. The Sapat complex underplates metabasalts of the Kamila amphibolite belt (i.e., Niat metavolcanic unit) and comprises ultramafic cumulates (dunites, peridotites and pyroxenites) at the base, layered gabbros in the middle and isotropic gabbros in the upper levels. The complex is folded through two phases of folding and metamorphosed under greenschist/lower amphibolite facies. The restored thickness of the complex approaches in excess of 2 kms.
The Main Mantle Thrust was mapped at several new locations during this study. Our observations show that the MMT at the base of the Sapat complex is younger than the melange/ olistostorm preserved in the upper parts of the Parla Sapat unit. The thrust cuts upsection laterally, and to the east of Babusar, occurs at the base of the Niat metavolcanic unit.