Precambrian tectonics and metacratonization in the NW Indian shield inferred from magnetotelluric imaging across the Marwar Terrane and Aravalli-Delhi Mobile Belt

The lithospheric architecture of the Marwar Terrane and Aravalli-Delhi Mobile Belt (ADMB) in the NW Indian shield is investigated using magnetotelluric (MT) imaging along a 600 km long NW-SE oriented Jaisalmer to Banswara profile across the two geologic domains that witnessed vigorous Proterozoic tectonic events. The lithospheric resistivity model generated through 3D inversion of MT data delineated conductive and resistive structures correlating with the Precambrian geology and evolution of the NW Indian shield. The resistivity model shows a moderately resistive upper mantle structure under the ADMB, surrounded by conductive zones, indi-cating anhydrous, cold sub-continental lithospheric mantle and deformed lithosphere zones. This is explained as the remnant of the Archean Aravalli craton that resulted from the metacratonization of the Archean lithosphere through the tectonic processes related to the Aravalli-Delhi orogeny. A low resistive upper mantle anomaly characterizes the Marwar lithosphere with a few conductive "fingers" penetrating through a resistive uppermost mantle and crust in the area. This is interpreted as the fossil zone of intense deformation and partial melting associated with the Neoproterozoic tectonothermal events experienced during the Delhi orogeny and pathways of magma outpour.