PALEOSTRESS STATES IN PARTS OF CHAKRATA FORMATION, GARHWAL HIMALAYA; EVIDENCE FROM STRIATED FAULTS

Abstract

Stratigraphically older Chakrata formation of Damtha Group of rocks overlie on Krol Nappe exposed in Garhwal Syncline. The contact between Blaini formation of Krol Group and Chakrata Formation is a thrust contact. This study targets at understanding of states of paleo-stress that is different stages of tectonic deformations, Chakrta Formation passed through, by analysis of Striated faults. Structural analysis was carried out on Rishikesh- Devprayag Highway (NH-58) from Kaudiyala to Bharpur area at stretch of around 17 km. Field data of striated faults has been 1. classified into homogeneous sets and then analysed by P-T Axis, Win-Tensor and Direct Inversion methods. Study reveals that this area has under gone 3 phases of tectonic activities. First one was transpressional movement proved by strike slip components of striated faults followed by an extentional regime which leads normal faults to be formed and at final stage compressive stress having direction NE-SW which is typically similar to Himalayan orogenic compression, reactivated the fault planes and formed reverse faults having similar features with the thrust contact between Blaini formation and Chakrata Formation. A geological map of this area is also been made to find out different types of faults distribution.