Lithospheric architecture in the Archaean Dharwar craton, India: A magnetotelluric model. (1st September 2018) - Kusham,
Graphical abstract: Highlights: Eastern Dharwar craton is devoid of conductors in the lithosphere. Western Dharwar craton shows conductors in the crust and upper mantle. Conductor in the upper mantle in WDC at a depth 120–150 km is due to graphite. Conductor below CSZ is due to refertilization during craton passage over the hotspot. Lithospheric thickness in the Dharwar craton is more than 200 km. Abstract: The lithosphere beneath the Archaean Dharwar craton was investigated with an east–west oriented, 280 km long profile (from Yellapura to Sindhanur) with 22 magnetotelluric stations. Regional strike directions, estimated were −5° and 13° for the crust and the lithospheric mantle respectively. Our results indicate in western Dharwar craton, presence of low resistivity zones in the crust besides two significant upper mantle conductive features within the highly resistive Archaean lithosphere. We analyze the available geophysical data that include heat flow, seismic tomography and magnetotellurics (MT) from the Dharwar craton. Our inference supports to the existence of a thick lithosphere. A thickness of more than 200 km is estimated for the lithosphere beneath the Dharwar craton by our magnetotelluric model. The study has brought out the presence of lithospheric upper mantle conductive features in the depth range of 100–200 km bounded to the west part of the magnetotelluric profile. Significant variations in conductivity are seen on either side of the Chitradurga shear zone. The conductive feature in the depth range 120–150 km is related with kimberlite melts and the conductive nature in the depth range 160–200 km is explained by refertilization process, as craton passed over the Marion (ca. 90 Ma) hotspot.