Sulfur and strontium isotopic compositions of carbonate and evaporite rocks from the late Neoproterozoic–early Cambrian Bilara Group (Nagaur-Ganganagar Basin, India): Constraints on intrabasinal correlation and global sulfur cycle

Abstract

Sulfur and strontium isotope ratios are presented for carbonate and evaporite rocks from the late

Age and implications of the phosphatic Birmania Formation, Rajasthan, India

“…Oddly, a correlation between the carbonate-rich Birmania Formation and the siliciclastic Jodhpur Group has also been suggested recently (Pandey and Bahadur, 2009), although justification for this suggestion was not presented. While recent studies have confirmed that the uppermost siliciclastic units of the Marwar Supergroup are indeed early Cambrian (Kumar and Pandey, 2008;McKenzie et al, 2011a), much of the lower part of the Marwar Supergroup, including the carbonate-rich Bilara Formation, is almost certainly late Neoproterozoic (Kumar, 2012;Mazumdar and Strauss, 2006) Thus, if the Bilara and Birmania formations are directly correlative, the latter is more likely to be Precambrian. Clearly then, the case for a Palaeozoic age for the Birmania Formation based on interpolation alone is weak.…”

Chapter 3 The Archaean and Proterozoic history of Peninsular India: tectonic framework for Precambrian sedimentary basins in India

“…The overlying Bilara Group consists of dolomite and stromatolitic limestone that conformably overlie the Jodhpur Group (Khilnani 1968;Barman 1987). In a somewhat confusing nomenclature, the Hanseran Evaporite Group is included within the Bilara Group, but as noted by Mazumder & Strauss (2006), these are coeval facies variants within the basin. The so-called Hanseran Group is characterized by seven evaporitic cycles of dolomite, magnesite, anhydrite, halite, polyhalite and clay bands (Das Gupta 1996;Kumar 1999;Mazumder & Strauss 2006).…”

“…In a somewhat confusing nomenclature, the Hanseran Evaporite Group is included within the Bilara Group, but as noted by Mazumder & Strauss (2006), these are coeval facies variants within the basin. The so-called Hanseran Group is characterized by seven evaporitic cycles of dolomite, magnesite, anhydrite, halite, polyhalite and clay bands (Das Gupta 1996;Kumar 1999;Mazumder & Strauss 2006). Unconformably overlying the Bilara Group is a sequence of fine-to coarse-grained, crossbedded, reddish brown, sandstone and siltstone of the Nagaur Group (Pareek 1984;Das Gupta & Bulgauda 1994;Mazumder & Bhattacharya 2004;Mahmoud et al 2008;Pandey & Bahadur 2009).…”

Trace fossils from the Nagaur Sandstone, Marwar Supergroup, Dulmera area, Bikaner district, Rajasthan, India

“…The stromatolites were reported as early as 1964 by Khilnani and Barman (1987) from the Bilara Group but none could be used for suggesting age. In recent years, the age of the Marwar Supergroup has been considered some where between Neoproterozoic and Cambrian (Mazumdar and Strauss, 2006). Very recently Kumar and Pandey (2008) discovered Rusophycus, Dimorphichnus and Cruziana trace fossils from the Nagaur Sandstone which gave important clues for the suggested Lower Cambrian age to the Nagaur Sandstone.…”