Structural geology of Kusma-Sirkang section of the Kali Gandaki valley and its bearing on the tectonic framework of Nepal Himalaya

Abstract

The rocks of the Kali Gandaki valley along the Kusma Sirkang section of Central West Nepal fall into two tectonic units having a marked difference in the grade of metamorphism. The units are demarcated by the NW-SE extending Phalebas Thrust which has been considered equivalent to the Chail Thrust of the Kumaon Himalaya by earlier workers. The Kusma Reverse Fault to the north parallels the Phalebas Thrust, both being related to Late Orogenic movements. The fold pattern shows at least four episodes, and it is believed that two of them existed prior to the main Himalayan orogeny of Tertiary time.