Crustal Evolution and Tectonics of the Archean Bundelkhand Craton, Central India

Abstract

Magnetotelluric studies over the Bundelkhand craton indicates a high resistivity sub-structure, typically observed in the Archean-Proterozoic regions. The geoelectric section shows a single high resistivity layer in the northern part of the craton, extending from surface to a depth of about 60 km and a three layered resistivity structure overlying a conductive bottom in its southern part. The geological studies reported earlier have delineated an EW trending zone of ultramafic rocks, called the Bundelkhand tectonic zone (BTZ), which marks the divide between the two electrical resistivity patterns. The geoelectric structure is broadly indicative of a northward dipping tectonic fabric in this region which conforms to the Himalayan subduction, to the immediate north of this craton. However this observation cannot explain the findings from geochemical, isotope analysis and geological studies, suggesting possible vertical block movements in the region, which are also indicated in the Bouguer gravity studies. The geoelectric structure beneath the Vindhyan group to the south shows low resistivities even up to 60 km, suggesting that the Bundelkhand craton which is characterized by high resistivity rocks, does not extend to the south beneath the Vindhyans, as was believed by the earlier researchers. A low resistivity body with an extremely high conductance of about 100,000 Siemens is delineated at the mid crustal depths beneath the exposed Bijawars south of Bundelkhand craton. The causative factors behind this low resistivity are not immediately apparent, but some possibilities are discussed here.

Electrical conductivity structure along a few transects over the Indian Lithospheric domains

“…Magnetotelluric studies were carried out in the region to the north of NSL zone from Jabera to Jhansi traversing across the Bundelkhand craton (Gokarn et al, 2013). The results clearly brought out a high resistive block extending from shallow depths to deeper levels of as much as 60 km.…”

Granite-hosted molybdenite mineralization from Archean Bundelkhand craton-molybdenite characterization, host rock mineralogy, petrology, and fluid inclusion characteristics of Mo-bearing quartz

“…The granitoids are traversed by regional eastwest trending subvertical sinistral shear zones (figure 1), e.g., Raksa Shear Zone (∼50 m wide; Senthiappan 1976Senthiappan , 1981 and Bundelkhand Tectonic Zone (∼up to 2 km thick; Pati 1998Pati , 1999Malviya et al 2006;Pati et al 2007Pati et al , 2008bSaha et al 2010;Gokarn et al 2013). The Bundelkhand Tectonic Zone has now been established as an Archean subduction zone (Malviya et al 2006;Saha et al 2010).…”

Redox series assessment, petrogenetic, and geodynamic appraisal of Neoarchean granites from the Bundelkhand Craton, Central India: Constraints from phase petrology and bulk rock geochemistry

“…The third stage is represented by the voluminous Neoarchean granites, formed in subduction-collision environments (Joshi et al, 2017;Kaur et al, 2016;Singh, Verma, Moreno, et al, 2019). The geoelectricsurvey based crustal structure also indicates the closure of oceanic crust coinciding with the CBTZ (Gokarn, Rao, Selvaraj, & Gupta, 2013). Considering the compositional variations of the Bundelkhand granites, in conjunction with the mineral chemical data as presented in this study, the geodynamic model for the origin of these rocks requires the involvement of mantle and crustal components and their interaction at various stages.…”