Coexistent pre-existing extensional and subsequent compressional tectonic deformation in the Kashmir basin, NW Himalaya

Abstract

This paper presents a new interpretation of overlapping differential deformations and likely causes of the structural heterogeneity within the Kashmir basin. Representing a prominent and distinctive strain feature in NW Himalaya, the broad geomorphic expression of the Kashmir as an elongated NW-SE trending sedimentary trough is inconsistent with general compression governing structural trend and deformation pattern of ∼2500 km long Himalayan Frontal Thrust zone. In addition to the general extensional geometry, there are prominent anomalous deformation features at varied spatial scales in the basins that imply dominance of extensional tectonics. We infer that contrary to the overall compression dominant mechanism of the Himalaya, the apparent extensional geometry of the basin connotes orogen-parallel extensional deformation (pull-apart), triggered by oblique convergence in the NW Himalaya. Moreover, we construe that the comparatively younger contractile (positive) features in form of the geomorphic convexity (push-up), accompanied by out-of-sequence reverse faulting (Balapur Fault, hereafter called as BF) within the basin which is generally believed to be associated with the uplift along NE dipping southern thrust complex (MBT/MCT), possibly resulted due to the tectonic reversal (positive inversion). The presence of the compressional features within the locally predominant extensional setting is suggestive of the basin's hybrid character—where variable tectonic regimes (earlier extension and subsequent compression) seem to be coexistent.