Abstract: A diverse assemblage of microorganisms are being discovered in black bedded, nodular and lenticular silicified cherts in the limestone/dolomite sequence of the Saradih Formation, Raipur Group, Baradwar sub-basin - a part of main Chhattisgarh basin, India. The composition of microbiota in the present assemblage includes 33 genera (9 acritarchs and 24 cyanobacteria) of different morphotypes categorized as: Acritarchs — Comasphaeridium, Dictyotidium, Favososphaeridium, Leiosphaeridia, Meghystrichosphaeridium, Navifusa, Tianzhushania, Trachyhystrichosphaera and Trachysphaeridium; Coccoids — Eoentophysalis, Eomicrocystis, Eosynechococcus, Glenobotrydion, Gloeodiniopsis, Myxococcoides, Palaeoanacystis, Scissilisphaera, Sphaerophycus and Tasmanites; Filaments — Archaeotrichion , Biocatenoides, Cephalophytarion, Cyanonema, Eomicrocoleus, Heliconema, Oscillatoriopsis, Palaeolyngbya, Partitiofilum, Polybessurus, Polythrichoides, Siphonophycus, Richnonema , and Veteronostocale. Like equivalent Proterozoic microbiota, the Saradih assemblage includes extensively well preserved morphotypes of both prokaryotic and eukaryotic affinities representing planktic and benthic habitats belonging to different groups and families. The mat forming and mat dwelling forms are abundant in Saradih assemblage. Mat-dwelling microbenthos and possible coastal microplanktons are abundant in subtidal to lower intertidal settings whereas, densely woven mat populations with few associated taxa characterized more restricted parts of tidal flats. The preservation of vertically oriented sheaths and bundles indicates that in these mats carbonate cementation was commonly penecontemporaneous with mat growth. The microbiotic population in present finding are widely recorded from the peritidal to open shelf carbonate facies of the Late Neoproterozoic (Cryogenian) sediments across world.

Abstract: Proterozoic grey to khaki grey shales of three localities from the Saraipali and Chhuipali Formations of the Singhora Group, Chhattisgarh Basin, contain diversified, exceptionally well preserved compressions and impressions of planktic and benthic meso-megascopic uni-multicellular eukaryotic metaphytes and rare prokaryotic thin films. These vegetative forms are millimeter-centimeters in size and varied shapes viz. straight to curve leafy-discoidal-palmate with and without parastem=holdfasts. A few are dichotomously branched and compactly entangled with numerous filaments. The present enigmatic remarkable thalloid fossil assemblage includes 19 taxa (viz. Beltina danai, Changchengia stipitata, Chuaria circularis, Enteromorphytes siniansis , Eopalmaria prinstina, Longfengshania fusiformis, L. ovalis, L. spheria, Palaeochorda vindhyansis, Phascolites imparilis, Proterotaenia montana, Siphonophycus solidum, Sitaulia minor, Tawuia dalensis, Tuanshanzia fasciaria, T. lanceolata, T. platyphylla, Tyrasotaenia podolica and Leiospheridia sp.) belonging to Cyanophyta, Chlorophyta, Phaeophyta, Rhodophyta and Xanthophyta algae. The morphology and associated characters of these diversified new fossils indicate the advent of eukaryotic multicellularity in the latest Palaeoproterozoic and polybiont algal diversity or paraphylly probably at two age intervals (1750 Ma and 1400 Ma), which mark evolutionary trends in Proterozoic life. The assemblage reveals an oscillating theromcline, congenial environment and subtidal-intertidal conditions within a photic zone for the two facies deposits in the Singhora Group.

Abstract In the last two decades multiproxy studies involving process-based sedimentology, geochronology of interbedded tuff units from different stratigraphic levels, sediment geochemistry including stable isotope signatures and documentation of structural grains within selective stratigraphic intervals from the Chhattisgarh Basin, central India have resulted in a perception change on various aspects of the basin fill including its time frame, stratigraphic framework and depositional architecture in the space–time domain. In addition to establishing a Mesoproterozoic ( c. 1450–1000 Ma) time frame for the basin on a strong foothold, these studies also proposed revision of its stratigraphy by introducing new stratigraphic units at ‘formation’ and ‘group’ level. From collation of available data, their critical evaluation and presentation of new data, the present work proposes a four-tier lithostratigraphy for the Chhattisgarh Supergroup, namely, Singhora Group, Chadarpur Group, Raipur Group and Kharsiya Group. Further, application of sequence stratigraphic rationale allowed the basin succession to be subdivided into four and three nonconformity/unconformity-bound depositional sequences in its eastern and western parts, respectively. The present chapter also highlights the potential of the basin for carrying out studies related to Mesoproterozoic ocean oxygenation and outlines the necessity of well-planned geophysical transects to resolve issues related to tectonic setup of the basin.