Geometry and Kinematics of strike-slip faults in the Dibrugarh field of the Upper Assam foreland basin, NE India

Abstract

Sedimentary basins within fold-and-thrust belts preserve the structural record of complex deformations and are essential to many orogenic systems worldwide. One of the component of such deformations is strike-slip tectonics. This research uses high-quality, three-dimensional seismic reflection data to investigate the geometry and kinematics of strike-slip faults developed within a geologically complex region in the Upper Assam foreland basin, NE India. Faults in the basin have a dominant NE-SW trend, with most faults in the SE and SW parts exhibiting sinistral strike-slip. These lateral movements are evidenced by extensional horsetail splay faults, negative flower structures, and minor transfer faults. The displacement profiles of the strike-slip faults also reveal complex segmentation, linkage, and mechanical interactions at different structural levels, indicating their prolonged histories and development. Tectonic tilts of the basin, along with sediment loading from the bordering fold-and-thrust belts over the geologic time, structurally changed the basin configuration giving rise to strike-slip deformations in the study region. These findings contribute to our knowledge of sedimentary basins within fold-and-thrust belts and their structural records of complex deformations.