Brittle Shear Tectonics in a Narrow Continental Rift: Asymmetric Nonvolcanic Barmer Basin (Rajasthan, India)

Abstract

Our field studies emphasizing brittle shear P-and Y-planes along the margins of the Barmer basin (Rajasthan, India) support its two-phase (NW-SE, followed by NE-SW) extension during Early Cretaceous and Late Cretaceous-Paleocene periods. We also document nearly NE-trending megascale transfer zones along the northern margin of the Barmer basin. Preexisting brittle planes in the Malani basement rocks guided the relay structures here. Structures at the western basin shoulder margin indicate NE-SW extension, and the crosscut relation connotes the relative timing of the two extension phases. The crosscutting conjugate fault sets are non-Andersonian. The NW-trending faults produced by the second-phase extension and the inherited NNW-trending brittle features are dominantly dip-slip. Prior fractures of the Malani rocks at ≥457 to the NE-SW principal extension direction extended the Barmer basin obliquely during the Late Cretaceous-Paleocene period. The asymmetric nature of the rift, too, connotes its oblique rifting. The extension direction of the first phase probably rotated clockwise. This is derived mainly from WSW-trending faults cutting NE-trending faults. Brittle planes of shear and fracture significantly promoted fluid flow, as understood from secondary hydrothermal mineral deposits (Barmer hill area) and pre-Deccan basalts (Sarnoo area). Reverse slip detected along subvertical faults on the western and eastern rift shoulders are probably due to isostatic flexure-related contraction or might be related to the farfield effect of ridge-push forces. The Mesozoic subsurface stratigraphy there and elsewhere within the Barmer basin requires more study to substantiate the potential for structural entrapment of hydrocarbon.

Structure and tectonic significance of high- and low-temperature deformation along the lateral escape-related Guaçuí and Batatal shear zones, southern Araçuaí Orogen (southeastern Brazil)

“…Tectonic implications of geological structures are interesting topics and detailed studies of this aspect are very significant (e.g. Kaplay et al 2016, Dasgupta and Mukherjee, 2017, Mukherjee et al 2018.…”

Source rock properties and kerogen decomposition kinetics of Eocene shales from petroliferous Barmer basin, western Rajasthan, India

“…It encompasses Barmer-Sanchor, Bikaner-Nagaur, and Jaisalmer sub-basins. In the Barmer sub-basin, Eocene Lower Barmer Hill Formation (Farrimond et al, 2015) is the major source rock, and this, along with the Fatehgarh Formation constitutes the major hydrocarbon reservoirs (Dasgupta and Mukherjee 2017). These formations have been identified in different wells drilled in the central and northern part of the basin.…”

Sedimentology and the facies architecture of the Ghaggar‐Hakra Formation, Barmer Basin, India: Implications for early Cretaceous deposition on the north‐western Indian Plate margin

“…Rifting in the Barmer Basin resulted from two distinct non‐coaxial extensional events (Bladon, Clarke, et al., ; Dasgupta & Mukherjee, ). An earlier north‐west to south‐east extensional phase, oblique to the present orientation of the basin, was followed by dominantly Palaeogene north‐east to south‐west extension (Bladon, Clarke, et al., ).…”

“…The Barmer Basin was considered to have developed in response to passage of the Indian Plate over the Reunion hotspot, giving rise to a syn‐ and post‐rift Palaeogene to Eocene sedimentary fill, overlying Precambrian rocks of the Malani Igneous Suite (Figure a, Crawford & Compton, ) and pre‐rift Mesozoic sediments (Compton, ; Sisodia & Singh, ). Recently, an important earlier northwest–southeast extensional event has been recognized, preserved in structural geometries exposed on the basin margins and overprinted by the perceived main Palaeogene rifting (Bladon, Clarke, & Burley, ; Dasgupta & Mukherjee, ). Fluvial sediments preserved on the rift margin are ascribed to the Lower Cretaceous Ghaggar‐Hakra Formation and rift margin geometries suggest that they were deposited contemporaneously with the pre‐Palaeogene normal faulting (Bladon, Burley, Clarke, & Beaumont, ; Bladon, Clarke, et al., ).…”