Geochemistry and petrology of the Chandarpur-Raipur sandstones: Implications for the evolution of the Chattisgarh Basin, Central India

Abstract

Depositional processes and stratigraphic evolution of the Chattisgarh basin exhibit a synergistic relation between sedimentation and tectonics. To interpret the sedimentation history and basin evolution, multiproxy approach including field studies, petrography, geochemical, and multivariate statistical analyses of the sandstones of Chandarpur and Raipur groups is employed. The study provides a detailed analysis of the time-connoted petrography and geochemistry of the sandstone units from each formation of the Chandarpur-Raipur sequence of Chattisgarh basin. The sandstones grade from immature wacke through submature arkose to mature quartzarenite from the bottom up the section. These sandstones are broadly characterized by felsic provenance, arid-humid palaeoclimate, and weak-intense palaeoweathering at the source. The assemblage of wacke-arkose-sublitharenite of the basal Lohardih Formation is characteristics of fan delta environment and represents initiation of rifting and basin formation stage. Subarkoses from the younging up sequence of Lohardih-Chaporadih-Kansapathar formations reflect prograding shelf environment that represents craton interior field of the continental block provenance and passive marginal tectonic setting, indicating gradual stabilization of the basin. Quartzarenites from Kansapathar Formation and stratigraphically younger Devsagar Member of Charmuria Formation also represent broadly similar provenance and tectonic setting indicating stable craton interior provenance in a passive marginal setting. Petrographic and geochemical analyses of some of the Kansapathar-Devsagar sandstones suggesting recycled orogen provenance, however, may be attributed to the orogenic activity and/or role of younger bimodal volcanic rock during rejuvenation of multistage basin opening faults. Rifting stage was followed by subsidence stage as indicated by the presence of black limestone capping the sandstone successions. Initiation of basin formation ∼1400 Ma and sedimentation can be correlated with the late-stage fragmentation of the supercontinent Columbia. The basin probably closed ∼1000 Ma during the assembly of the next supercontinent Rodinia. It is estimated that ∼87% of the 2.2-km-thick sedimentary succession in the eastern Chattisgarh basin, were already deposited within this time frame (∼1405 and ∼1007 Ma). The basin is correlatable with other Mesoproterozoic basins of Peninsular India like Vindhyan, Cuddapah basins, as well as with basins like Xiong’er rift basin of North China Craton, Espinhaco basin of eastern Brazil, that are related to the Columbia-Rodinia Supercontinent cycle.