Tracking sources and paleotectonic settings of Mesozoic sandstones in interlinked rift basins of western India: An integrated approach using petrography and heavy mineral chemistry
Pawan Kumar Rajak, Angana Chaudhuri, Naraga Prabhakar, Santanu Banerjee
Abstract
Based on integration of field, petrographic and heavy mineral chemical data, this study highlights the source and tectonic setting of the Mesozoic sandstones of Kutch, Saurashtra, Narmada and Cambay basins at the western margin of India, formed by the progressive splitting of the eastern Gondwanaland. The Kutch Basin is dominated by arkosic sandstone, whereas Saurashtra, Narmada and Cambay basins show the predominance of sub-arkose and sub-litharenite. The modal analyses of framework grains in Kutch sandstones indicate basement uplift and transitional continent settings. In contrast, the sandstones of Saurashtra, Narmada and Cambay basins bear imprints of recycled orogenic and craton interior belts. The presence of abraded and detrital quartz overgrowth and rounded zircons in most sandstones reveal the recycling of sediments in these basins. Tourmaline and rutile mineral compositions constrain the possible lithology of source rocks. The tourmaline mineral chemistry (Ca-Fetot-Mg plot) suggests the derivation of sediments from various sources, including Li-poor granitoids associated with pegmatites, aplites, Ca-poor metapelites, metapsammites and quartz-tourmaline-rich granitic rocks. The compositions of rutile grains (Cr vs. Nb plot) in sandstones indicate metapelitic sources. The gamut of all mineral chemical data supports the predominance of sediment sources from quartzo-feldspathic rocks with minor inputs from mafic rocks. Based on available paleocurrent data and correlation of source compositions, we infer that the Mesozoic sediments of Kutch, Saurashtra, Narmada and Cambay basins were primarily sourced by various lithologies of the Aravalli Craton. The Narmada Basin possibly received additional sediment input from the Bundelkhand Craton.