Tuff Beds in Kurnool Subbasin, Southern India and Implications for Felsic Volcanism in Proterozoic Intracratonic Basins

GEOSCIENCE FRONTIERS 3(4) (2012) 429e444 available at www.sciencedirect.com China University of Geosciences (Beijing) GEOSCIENCE FRONTIERS journal homepage: www.elsevier.com/locate/gsf RESEARCH PAPER Tuff beds in Kurnool subbasin, southern India and implications for felsic volcanism in Proterozoic intracratonic basins Dilip Saha*, Vikash Tripathy 1 Geological Studies Unit, Indian Statistical Institute, Kolkata 700108, India Received 25 October 2011; received in revised form 17 January 2012; accepted 19 January 2012 Available online 10 February 2012 KEYWORDS Abstract A first report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in Felsic tuff; southern India is presented. The rhyolitic to rhodacitic tuffs, overlying shelfal limestones formed at Intracratonic basin; depths below storm wave base, have rheomorphic features indicative of viscoplastic flow, and geochem- Kurnool subbasin; ical signatures of rhyolitic to rhyodacitic unwelded to welded tuffs, similar to those described from other Owk Shale; Proterozoic intracratonic basins like Vindhyan and Chhattisgarh basins in India. Fragmentary nature of Proterozoic altered glass with perlitic cracks and local admixture with intrabasinal sediments suggest phreatomag- matic reactions. The widespread and repeated occurrences of felsic tuffs in these basins, possibly derived from low degree melting of continental crust, suggest intermittent tectonothermal instability which likely influenced basinal topography and cyclic development of the carbonate platforms. ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved. 1. Introduction Large Phanerozoic intracratonic basins, e.g. those in North America, * Corresponding author. are situated away from known plate boundaries, and their origin and E-mail address: [email protected] (D. Saha). subsidence has been modeled as linked with thermal anomalies 1 Present address: A-1/79, Sector-18, Rohini, New Delhi 110089, India beneath thick continental lithosphere (e.g. Kaminski and Jaupart, 1674-9871 ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved. 2000). These basins show near symmetric disposition of basin in- fill with maximum thickness of preserved sedimentary sequences Peer-review under responsibility of China University of Geosciences in central part of the basin, possibly caused by basin centered (Beijing). subsidence. Various transgression-regression cycles have also been doi:10.1016/j.gsf.2012.01.002 studied from facies analysis in such basins (e.g., Shao et al., 2011). Proterozoic intracratonic basins differ in many respects from their Phanerozoic counterparts (Friedman et al., 1992; Eriksson et al., 1998), and shallow epeiric seas constitute a major depositional Production and hosting by Elsevier setting for the Proterozoic intracratonic basins including the Prote- rozoic (Purana) basins in India (Chakraborti, 2006). Traditionally, 430 D. Saha, V. Tripathy / Geoscience Frontiers 3(4) (2012) 429e444 a sag basin model or initiation through passive continental rifts kimberlites and lamproites, multiple events of lithospheric followed by subsidence has been invoked in understanding the stretching and consequent partial melting beneath the Eastern tectonic evolution of these basins. However, there is a growing Dharwar craton is likely to have important bearing on the devel- tendency to interpret the development of these plate-interior basins opment of volcano-sedimentary successions within the polyhistory as linked to plate margin processes as well (e.g. Shaw et al., 1991), Cuddapah basin (Kingston et al., 1983; Saha and Tripathy, 2012). and global tectonic events of supercontinent break-up and assembly We report here for the first time the occurrence of felsic tuffs from (e.g. Dharma Rao et al., 2012). For example, the Late the Kurnool Group which unconformably overlies the ca. 1900 Ma ProterozoiceEarly Paleozoic central Australian basins including the old Chitravati Group in the western part of the Cuddapah basin. Amadeus basin, show effects of initial mantle perturbation and short Documentation of the nature of these felsic volcanics/volcani- lived sag basin development, possibly triggered by insulating effects clastics, their geological association and influence on the ongoing of the Rodinia supercontinent, and of far field effects of horizontal sedimentation is important in constraining how intracratonic stresses related to subsequent compressional regimes reactivating sedimentary basins respond to passive rifting triggered by litho- the early crustal fabric (Lindsay, 2002). Post-800 Ma development in spheric stretching, mantle melting and possible continental central Australia led to segmentation of the initial much larger sag underplating by mafic magmas. The NeoarcheaneEarly Paleo- basin into a number of sub-basins with asymmetric distribution of proterozoic amalgamation of the cratonic blocks of India was the sediment thickness patterns. Thus evolution of the even the followed by widespread development of the Proterozoic basins in interior basins can be complex, and study of the intercalated all the major blocks (Meert et al., 2010). These basins have volcanics within these basins and their regional context may provide a prolonged history of sedimentation, extending over at least important clues on the tectonic evolution of the Proterozoic intra- 1000 Ma as in the case of the Cuddapah basin which shows three cratonic basins with a protracted history. major unconformity bound sequences and maximum flooding A number of publications in recent years highlight occurrence events (Saha and Mazumder, 2012). The repeated opening and of felsic tuffs from the Proterozoic basins in India, and their inversion of the basins (or sub-basins) as indicated by the basin- tectonic implications. While tuff beds from the Sindreth Group in wide angular unconformities within an overall intracratonic western Rajasthan are interpreted to be associated with Cry- framework needs cyclic tectonothermal instability. In this paper ogenian (666e644 Ma) subduction related volcanic arcs (Dharma we highlight the possible connection between felsic volcanism, Rao et al., 2012), those from ca. 1400 Ma old Singhora tuff in the pulsed development of carbonate platforms, and the overall Chhattisgarh Basin are also considered to be of volcanic arc tectonic framework of the large intracratonic Proterozoic basins in setting (Das et al., 2009). The 990e1020 Ma old Sukhda Tuff India, particularly with reference to the Cuddapah basin. from the upper part of the Chhattisgarh Supergroup has rhyolitic affinity (Patranabis-Deb et al., 2007), but there is no detailed information on the tectonic setting of the magmatic activity except 2. Geologic background a broad hint that the felsic eruption toward closure of the basin may be related to Rodinia amalgamation (Patranabis-Deb and The polyhistory Cuddapah basin (area w45,000 km2) occurring in Chaudhuri, 2008). the eastern part of the Eastern Dharwar craton, southern India, The peninsular India hosts a number of large Proterozoic represents the second largest Proterozoic basin in India as far the basins with cumulative sediment thickness up to 8e10 km as in outcrop extent is concerned (Ramakrishnan and Vaidyanadhan, the Cuddapah basin occurring in the Eastern Dharwar craton 2008), and recent studies link the origin of this basin to the (Nagaraja Rao et al., 1987; Chaudhuri et al., 2002; Ramakrishnan separation between Napier Complex and Dharwar Craton and Vaidyanadhan, 2008). Unconformity bound sedimentary (Mohanty, 2011). Three major unconformity bound sequences successions in these intracratonic basins have recently been constitute the Cuddapah Supergroup which is unconformably interpreted to have links with sea-level changes (Patranabis-Deb overlain by the Kurnool Group (Meijerink et al., 1984; Nagaraja et al., 2012), possibly influenced by more than one cycle super- Rao et al., 1987; Chaudhuri et al., 2002, Table 1). While the continent break-up and assembly through the Paleoproterozoic to Pulivendla mafic sills are dated at >1817 Ma (Rb-Sr age, Bhaskar the Eocambrian (Saha and Tripathy, 2012). Felsic volcanics/vol- Rao et al., 1995) and more recently the Tadpatri mafic/ultramafic caniclastics from the lower part of the Vindhyan Supergroup in the sills are dated at 1900 Ma (Ar-Ar ages, Anand et al., 2003; French Bundelkhand craton, from the Chhattisgarh Supergroup in the et al., 2008), the Kurnool Group is traditionally regarded as Bastar craton, from the Somanpalli Group in the Pranhita- Neoproterozoic (Ramam and Murty, 1997; Ramakrishnan and Godavari basin are well documented (e.g. Saha and Ghosh, Vaidyanadhan, 2008; Sharma, 2011). The Neoproterozoic 1987, 1998; Patranabis-Deb et al., 2007; Mishra and Sen, 2008). assignment for the Kurnool Group is based on (i) the major basin Although mafic flows, sills and dykes are common in the western wide angular unconformity between the Cuddapah Supergroup part of the Cuddapah basin (Nagaraja Rao et al., 1987; Anand and the Kurnool Group; (ii) the diamondiferous Banganapalle et al., 2003), felsic tuffs are rare in the lower Cuddapah succes- conglomerate at the base of the Kurnool Group; w1090 Ma old sions of the Papaghni Group and the Chitravati Group, except that Kimberlite pipes (Chalapathi Rao et al., 1999) at the western the middle to upper part of the Tadpatri Formation (Chitravati margin of the basin being the

Load more