Kinematics of the Transverse Lineaments, Regional Tectonics and Holocene Stress Field in the Garhwal Himalaya

Lineament and fracture trace analyses of the Indo-Gangetic Plain and different tectonic units of the Garhwal Himalaya reveal four important sets with strike-slip sense of movements. Horizontally-displaced lithologic and tectonic boundaries clearly depict the sense of displacement along certain lineaments, e.g. the Ganga and Yamuna. Also, small-scale straight fracture traces generally are associated with major fracture traces of lineaments in the sense of Riedel (R), Conjugate Riedel (R'). Displacement (D) and Thrust shears (P). L₁ lineaments trend N5°-N10° and show dextral sense of displacement, while its conjugate sinistral set (L₃) trends N50°. The other strike-slip fracture traces and lineaments trend N25° (L₁) and N90° (L₃) with a dextral and sinistral sense of displacement respectively. Kinematically. it seems that the orientation of maximum principal horizontal stressU 1. deduced from lineament and fracture trace analysis, has changed anticlockwise from N60° to N24° in space and time by an amount of 35°. Interplay of some important faults along some lineaments with the Krol Thrust in frontal parts of the Krol Thrust Sheet has produced the Dehradun Re-entrant as a lateral ramp unlike the other re-entrants in the Himalaya. Furthermore, present-day seismicity in the Garhwal Himalaya is controlled by certain transverse lineaments besides being associated with major thrusts.