Uranium-Pb ages of detrital zircon from the Mesoarchean Sukma and Neoarchean Bengpal supracrustal groups: Evidence for unconformable stratigraphic relations and implications for Precambrian stratigraphy of the Bastar Craton, southcentral India

Records of terrestrial detritus deposited since the Mesoarchean, preserved in sedimentary basins on cratons, are useful in continental reconstruction. The southern segment of the Bastar craton comprises Paleoarchean cratonic fragments extensively reworked, and intruded by granite batholiths, during the Neoarchean and expose two major groups of supracrustal successions. The Sukma Group, occurring as amphibolite-facies remnants within Neoarchean granitoids are mostly chemogenic supracrustal rocks in contrast to the low-to unmetamorphosed Neoarchean volcano-sedimentary Bengpal Group. In order to resolve their uncertain stratigraphic relationship, detrital zircon U-Pb analyses were carried out to obtain detrital age spectra. The youngest concordant detrital zircon 207Pb/206Pb ages from the Sukma Group metapelite (CB11C) and micaceous quartzite (CH5B) samples places its maximum depositional age at < 3.10 Ga (3128 +/- 6 Ma, cumulative maximum depositional age of both samples). In contrast, the micaceous quartzite (samples CB14 and CB18) from the Bengpal Group were deposited after 2.4 Ga (2350 +/- 16 Ma, cumulative maximum depositional age of both samples), indicating a considerable hiatus in depositional history of these two supracrustal successions. Comparison with globally compiled age spectra from cratonic Archean-aged metasedimentary successions indicate that a most likely clastic sediment provenance to the dominantly chemogenic Sukma Group was from the Western Dharwar and Singhbhum cra- tons. The inferred provenance cratons are based on the presence of extensive Mesoarchean granitoid batholiths and, therefore, indicates their proximity at least till 3.0 Ga. In contrast, clastic detritus to the possibly riftogenic volcano-sedimentary Bengpal Group was largely sourced from the voluminous Neoarchean magmatism probably from within the Bastar craton.

Automated summary

The southern segment of the Bastar craton is composed of Paleoarchean cratonic fragments intruded by granite batholiths. Two major supracrustal successions, Sukma Group and Bengpal Group, exist within this segment. Detrital zircon U-Pb analysis reveals that the depositional age of the Sukma Group is older than 3.1 Ga, while the Bengpal Group was deposited after 2.4 Ga.