Chapter 15 - Detrital Zircon U-Pb Geochronology, Nd Isotope Mapping, and Sediment Geochemistry From the Singhora Group, Central India: Implications Toward Provenance, Its Shift, and Regional Stratigraphic Correlation

Abstract

Proterozoic sedimentary basins at the margin of Archean cratons are repositories of detritus not only from multiple cratonic domains but also from cratonized orogenic belts that become integral parts of continental clusters stitched at different ages and bear records of multiple tectonic pulses. In this chapter, we studied detrital records of provenance and its shift in the Mesoproterozoic Singhora Group, central India, that occupies a strategic geotectonic position at the boundary between the Archean Bastar Craton and Proterozoic Eastern Ghats Granulite Belt. Zircon grains from arenaceous intervals across stratigraphic columns of the basin were measured for their U-Pb isotopic ages using SHRIMP II and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). For comparison, we also analyzed zircon grains from basement granitic gneiss, sandstone units from lower part of the Chandarpur Group of rocks, and the basal sandstone from the adjoining Khariar basin. Bulk rock geochemistry and Sm-Nd isotopic analysis (TIMS) of the Singhora Group were also carried out. From the youngest population of detrital zircon, the age of sedimentation in the Singhora basin is estimated at <1600Ma. Also, it is deciphered that an early detrital source dominated by ∼2500Ma zircon population changes abruptly from the middle part of Singhora stratigraphy (i.e., the Bhalukona Formation) upward with addition of Paleoarchean (3511±3Ma) and Mesoproterozoic (1639±18Ma) sources. The trend continues in stratigraphy up to the Chandarpur Group of Chhattisgarh Main Basin, albeit without Paleoarchean contribution. Sympathetic signature could also be noticed in Nd isotope ratios, which record a major shift toward more negative εtNd values from the middle tier of Singhora stratigraphy. Comparison of detrital zircon age population data with data from another adjoining basin, viz. the Ampani basin, strengthened the idea that both the basins record new source addition from middle parts of their respective stratigraphy and thus, merit interbasin correlation.