Provenance of mesozoic sandstones in the Saurashtra Basin using heavy minerals geochemistry and geochronology: Implications for paleogeographic reconstruction in Western India

Abstract

Two contrasting Precambrian sources has been established for the Mesozoic sediments of the Dhrangdhara Group at the western margin of India based on the integration of petrography of sandstone, mineral chemistry of tourmaline and rutile, and U–Pb zircon and U–Th–total Pb monazite dating. The geochemical characteristics of rutile and tourmaline indicate sediment supply from metapelites, granites, pegmatite, quartz vein and tourmalinites. The potential source terrains for these stratigraphic zones are comprehended on the basis of the overlap of probability density of zircon and monazite ages. Zircon trace elements and REE concentrations suggest its derivation from granitoids. U–Pb zircon age data reveals four major populations at 3584–2502 Ma (Archean), 2499–1642 Ma (Paleoproterozoic), 1595–1010 Ma (Mesoproterozoic) and 993–539 Ma (Neoproterozoic). In contrast, U–Th–total Pb monazite age data show major age populations at 900–700 Ma and 500 Ma. The mineral chemistry signatures and zircon-monazite age data indicate predominant sediment derivation from metasedimentary rocks of the Aravalli and Delhi supergroup of rocks, with limited input from Archean gneissic (e.g., Mewar Gneisses and equivalents) and granitic (e.g., Berach Granite and equivalents) rocks. Besides, the predominance of zircon and tourmaline grains with high textural maturity supports significant input from sedimentary and metasedimentary rocks from the Aravalli Delhi Fold Belt (ADFB) and Marwar Supergroup. The detrital zircon and monazite age distributions are consistent with the major Precambrian supercontinent assemblies and corresponding orogenies. The Archean age (2.6–2.5 Ga) components correspond to the Bhilwara Orogeny of the ADFB, 1.8–1.7 Ga and 1.0–0.9 Ga correspond to the tectonothermal events associated with the assembly of Columbia and Rodinia supercontinents, respectively. The Neoproterozoic younger age ∼0.75 and ∼0.65–0.50 Ga corresponds to the breakup of the Rodinia supercontinent and the assembly of the Gondwana supercontinent, respectively. The mineral chemical and geochronological data track major global and local orogenies recorded within the ADFB. Therefore, the sedimentary succession of the Saurashtra Basin preserves the records of paleo-drainage pattern and paleogeography of the northwestern margin of eastern Gondwanaland, which is a repository of the sediments derived from the Aravalli-Delhi fold belt and Pan-African orogenies.