Active tectonics of the Thoubal‐Chandel Thrust, Manipur Hills, Indo‐Myanmar Range, northeast India: Insights into deformation pattern of adjacent thrust sheets in a growing orogen

Abstract

The NE–SW trending and SE dipping Thoubal‐Chandel Thrust (TCT) in eastern Manipur Hills of the Indo‐Myanmar Range (IMR) places the Thoubal‐Chandel thrust sheet over the Churachandpur‐Mao thrust sheet. Despite being seismically active, the active tectonic aspects of the major structural discontinuities within the IMR, including TCT, are not yet studied in detail. The present study aims to examine the active tectonics of the TCT and other associated faults, with particular focus on deformation of the Churachandpur‐Mao, and Thoubal‐Chandel thrust sheets. Association and disposition of landforms, and statistical analyses of Mountain‐front Sinuosity Index (Smf), Stream Length‐Gradient Index (SL), Hypsometric Integral (HI), Drainage Basin Asymmetry Factor, and Transverse Topography Symmetry Factor (T) reveal that both of these adjacently lying thrust sheets are actively uplifting due to oblique‐slip movement on their basal thrusts, but with spatially variable rates. In general, higher SL (mode = 219) and HI (mode = 0.527) in large parts suggest faster uplift of the Thoubal‐Chandel thrust sheet than the Churachandpur‐Moa thrust sheet, which has comparatively lower SL (Mode = 140) and HI (mode = 0.416). However, differential along‐strike uplift rates have caused tilting of both the thrust sheets. Faster uplift of the northern part of Thoubal‐Chandel thrust sheet has caused its overall southward down‐tilting, whereas faster uplift of the southern part of Churachandpur‐Mao thrust sheet has caused its overall northward down‐tilting. The study brings out that the deformation pattern of even the adjacent thrust sheets of growing orogens could be at stark variance albeit the same stress regime.