Segmentation of continental Indian plate by the Narmada‐Son diffuse plate boundary

Abstract

The Narmada‐Son lineament is a major tectonic feature in Central India. Here we employ data from geodetic measurements of crustal deformation and upper mantle P‐wave travel time tomography and propose that the Narmada‐Son palaeo‐rift is a present‐day diffuse plate boundary that segments the continental part of the Indian “composite” plate into two component plates, the North and South‐Indian plate. Tomographic images reveal that the collision of an indenter, associated with the relatively faster moving South‐Indian plate, with the Narmada‐Son diffuse plate boundary acted as a pivot point exerting a torque on one of the component plates along with mechanical rotation. This new proposal along with a new identity of the Narmada‐Son diffuse plate boundary is in better agreement with the estimated location of the relative Euler pole across two respective component plates. Our model is also able to better explain the Indian “composite” plate hypothesis, diversity in the topographic architecture along the rift, and contrasting deformation styles on either side of the diffuse plate boundary.

Unfolding rotational tectonics and topographic evolution from localized verses diffuse plate boundary counterparts

“…The Narmada-Son paleo rift zone has been identified as a failed rift arm 28 , 29 and it has been proposed that this structurally weak zone may have been reactivated by igneous activity at the Cretaceous-Tertiary boundary. Unusual moderate to high magnitude seismicity occurrences (M > 6) have been reported in this plate interior region of the Indian subcontinent 9 . Hence, the nature of present-day crustal deformation, earthquake generation processes and its relation with the associated topography build-up along this paleo rift zone within Central Indian remains poorly understood.…”

“…In this article, we present new analyses to support the recently proposed interpretation of present-day crustal deformation of the Central Indian Tectonic Zone (CITZ) as a new type of rotational tectonic system involving a diffuse plate boundary between the North India Plate and South India Plates 9 , and compare it to the Gakkel Ridge-Chersky Range rotational tectonic system in the Arctic (Fig. 2 ).…”

“…Although the above geodetic analysis seems to suggested that the Indian plate is behaving in a rigid block manner, the occurrence of unusual strong earthquakes of M > 6.0 inside the continental parts of Indian plate implies that the entire plate is in fact not behaving as a single rigid block. Hence, we also test the ‘composite’ plate hypothesis put forward by Sen et al 9 which involves two ‘component’ plates (i.e., N-India and S-India) separated by the Narmada-Son paleo rift zone.…”

“…The CITZ is a significant seismo-tectonical active zone within the Indian plate’s interior region, which stretches ENE–WSW for more than 1000 km, is ~ 400 km in width and dissects the Indian Peninsula into a northern and a southern crustal block 24 , 25 (Fig. 2 b) that can be identified as a diffuse deformation zone 9 . The precursor of the CITZ was possibly formed by a Precambrian continental–continental collision phase within Peninsular India and this zone has witnessed various major events such as the extrusion of the voluminous Deccan flood basalts in the late Cretaceous 25 – 27 .…”

“…2 ). Our endorsement of this new rotational tectonic interpretation, rather than the previous general assumption that the Indian Plate behaves as a single rigid block (REF) 10 , of the CITZ is based on a multidisciplinary approach, in which we first analyze plate motions using Global Navigation Satellite System (GNSS) velocities from the Arctic region (as a classic rotational tectonic system), and compare these with a geodetic analysis of the CITZ 9 , Moreover, a new kinematic model is developed by re-estimating Euler poles and angular velocities. We furthermore perform a topography analysis for the both cases (i.e., CITZ and Gakkel Ridge in the Arctic) and reanalyse the analogue model of rotational tectonics proposed by Zwaan et al 3 .…”