Detrital zircon U-Pb geochronology of stromatolitic carbonates from the greenstone belts of Dharwar Craton and Cuddapah basin of Peninsular India

Oldest rocks are sparsely distributed within the Dharwar Craton and little is known about their involvement in the sedimentary sequences which are present in the Archean greenstone successions and the Proterozoic Cuddapah basin. Stromatolitic carbonates are well preserved in the Neoarchean greenstone belts of Dharwar Craton and Cuddapah Basin of Peninsular India displaying varied morphological and geochemical characteristics. In this study, we report results from U-Pb geochronology and trace element composition of the detrital zircons from stromatolitic carbonates present within the Dharwar Craton and Cuddapah basin to understand the provenance and time of accretion and deposition. The UPb ages of the detrital zircons from the Bhimasamudra and Marikanve stromatolites of the Chitradurga greenstone belt of Dharwar Craton display ages of 3426
26 Ma to 2650
38 Ma whereas the Sandur stromatolites gave an age of 3508
29 Ma to 2926
36 Ma suggesting Paleo- to Neoarchean provenance. The U-Pb detrital zircons of the Tadpatri stromatolites gave an age of 2761
31 Ma to 1672
38 Ma suggesting Neoarchean to Mesoproterozoic provenance. The Rare Earth Element (REE) patterns of the studied detrital zircons from Archean Dharwar Craton and Proterozoic Cuddapah basin display depletion in light rare earth elements (LREE) and enrichment in heavy rare earth elements (HREE) with pronounced positive Ce and negative Eu anomalies, typical of magmatic zircons. The trace element composition and their relationship collectively indicate a mixed granitoid and mafic source for both the Dharwar and Cuddapah stromatolites. The 3508
29 Ma age of the detrital zircons support the existence of 3.5 Ga crust in the Western Dharwar Craton. The overall detrital zircon ages (3.5e2.7 Ga) obtained from the stromatolitic carbonates of Archean greenstone belts and Proterozoic Cuddapah basin (2.7e1.6 Ga) collectively reflect on w800e900 Ma duration for the Precambrian stromatolite deposition in the Dharwar Craton.