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The low-grade meta-sedimentary sequence of the Sirohi Group comprises an ensemble of phyllite, schist and meta-carbonate rocks (including impure marble) and marks late Proterozoic tectonics in the NW Indian block. The δ18OV-PDB values for Sirohi meta-carbonates range from -20.2 to -101‰, suggesting that the Oisotopic signatures have been variably affected by post-depositional alterations. The δ13CV-PDB fluctuate from marginally positive (~1.0‰) to negative (-3.3‰) values and represent primary sedimentary signatures. The Mn-Sr and Mg-Ca relationships further substantiate that the C-isotopic characteristics have not been significantly modified during the metamorphism. The δ13CV-PDB values are typical of normal carbonate sediments and suggest warmer climatic conditions during their deposition, most likely prior to the Neoproterozoic 'snowball earth'. Evidence of glaciation in stratigraphically younger litho-units (occurrence of possible diamictite, glacial striations, etc. in the immediately overlying Sindreth Group and Marwar Supergroup) can be correlated with the worldwide glacial events during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

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The article discusses the angular unconformity between rocks of the Aravalli Supergroup (ASG) and the Delhi Supergroup (DSG) in Southeastern Rajasthan, India. It cites the primary lithounits of the ASG and DSG rocks. Staurolite is observed in the ASG rocks while mineral compounds of schist facies and chlorite are seen in the DSG rocks. The difference in the initial stages of structural evolution of Aravalli and Delhi supergroups was traced to an angular unconformity between Delhi and pre-Delhi.