THE DHARWAR CRATON: EXPLORING THE POSSIBILITY OF POST-CRATONIZATION ROTATION USING ASPECT GEODYNAMIC MODELS

Peninsular India has a geologic history spanning over three (3) billion years of geologic time and comprised of five (5) Archaean cratons or six if the Mewar is included as part of the Northern Indian Block (Aravalli and Bundelkhand Cratons). The Southern Indian Block includes the Dharwar, Bastar and Singhbhum Cratons. The Dharwar craton is divided into two distinct regions based on lithology and age (Western Dharwar Craton (WDC) and Eastern Dharwar Craton (EDC)) and has a prominent south to north bend giving the entire craton a curvilinear shape. There are two end member explanations of how/when the curvilinear shape was imposed on the craton. The first argues that the curvilinear feature is a primary (pre-stabilization, Meso-Archean) whereas the secondary hypothesis posits a post-stabilization rotation within the craton. The latter explanation argued that an ~30-degree vertical axis rotation resulted in a re-alignment of mafic dyke trends in the Paleoproterozoic (Soderlund et al, 2019). Assessment of declination obtained from paleomagnetic data from North and South Dharwar offers some ambiguous support for Paleoproterozoic rotation but fails to yield conclusive evidence. The dyke swarms examined in that study indicate that any post-stabilization rotation occurred prior to the emplacement of ~1886 Ma dykes. We investigate the possibility of a secondary curvilinear feature (by assuming an initial linear shape for the Dharwar Craton) by employing geodynamic modeling using ASPECT (Advanced Solver for Problems in Earth's ConvecTion) and available paleomagnetic data. ASPECT is an open-source geodynamic software that allows users to vary deep-earth conditions to investigate the effects of these varying conditions on both surface and subsurface observations. Our model is set up to run for several time-steps equivalent to the 2082-1888 Ma interval which brackets the window for any deformation and tectonism required for bending the ‘linear’ Dharwar craton by about ~20°. Computations of the force required to deform a stabilized craton and the different iterations of input parameters will be presented. We discuss our position on whether the ‘oroclinal-type’ features in the Dharwar Craton pre/post-stabilization are based on computed forces and whether or not they can be realistically generated on earth through collisions or other triggering mechanisms.