Archean crustal evolution and building of habitable continents: Insights from the Western Dharwar Craton

Abstract

This contribution presents a comprehensive review synthesis addressing the time frame and processes involved in formation of Archean continental crust, surface environments, oxygenation and microbial activity leading to building the habitable continent in the western Dharwar craton (WDC). The WDC preserve ca. 3600-2600 Ma crustal record comprising TTGs, volcanic-sedimentary greenstones and potassic granites.  U-Pb zircon ages and Sm-Nd whole rock isochrons suggest successive stages TTG accretion and greenstone volcanism contribute to episodic continental growth during ca. 3450-3350 Ma, 3300-3200 Ma, ca. 3230-3150 Ma, ca. 3000-2900 Ma, 2700-2600 Ma with crustal reworking ca. 3150 Ma, ca. 3000-2950 Ma, 2600 Ma and ca. 2500 Ma. Elemental and Nd isotope data of ca. 3380-3150 Ma greenstone volcanics reveal their derivation from primitive to deep mantle reservoirs in plume setting whilst ca. 3000-2900 Ma volcanism originated in shallower undepleted mantle caused by asthenosphere upwelling. On the other hand, ca. 2700-2600 Ma volcanics generated by melting of depleted to enriched sources in arc settings.   Collision of arcs with eventual slab breakoff leads to generation and emplacement of Chitradurga-Arsikere-Banavara potassic plutons in the basement or in between the volcanic arcs.

Redox sensitive elements and isotope biomarkers (FE, N and MIF-S) data on the sedimentary record reveal dominantly anoxic environments during ca. 3400-3000 Ma whilst ca. 3000 Ma onwards a shift from anoxic to minimum oxygen on ocean surface with periodic organic production linked to the microbial activity and oxygenation building of habitable continent few hundred million years prior to GOE.