Content area
Full text
Abstract
The Cuddapah Uranium Province encompasses two economically viable genetic types of uranium deposits as the carbonate-hosted stratabound uranium deposits around Tummalapalle-Rachakuntapalle area, and the unconformity-proximal type in basement granitoids and overlying Srisailam/ Banganapalle quartzite in the Lambapur-Peddagattu-Chitrial-Koppunuru area . Besides, the basin characteristically hosts important occurrences, of fracture controlled uranium mineralisation in Gulcheru quartzite near Gandi and in basement granitoid around Lakkireddipalle-Rayachoti; shear-controlled along the thrusted eastern margin of Cuddapah basin in basic metavolcanics and schists at Gudarukoppu and Kasturigattu. In the northern part of the basin, uranium deposits of Lambapur, Peddagattu, Chitrial, and Koppunuru area characteristically show association of ore bodies along structures formed by intersection of prominent basement fractures with the unconformity separating Srisailam and Palnad sediments from the basement. In the southwestern part of the basin, potential carbonate-hosted, stratabound uranium mineralisation extends over a 160 km long belt from Chelumpalli to Maddimadugu with large-tonnage, low-grade, uranium deposits in Tummallapalle-Rachakuntapalle area. The unconformity-proximal and fracture controlled deposits/prospects characteristically share a common source for uranium, repeated tectonism, weathering of the basement granitoids and episodic, epigenetic hydrothermal processes of uranium mineralisation. This paper evaluates the role of granitoids spatially and temporally associated with uranium mineralisation in making the Cuddapah Basin a unique uranium province.
Keywords: Cuddapah Basin, Uranium Mineralisation, Granites, Tectonics, Geochemistry
I. Introduction
The Cuddapah uranium province exhibits several styles of uranium mineralisation of varying ages. In the northern part, unconformity related uranium mineralisation at Lambapur-Peddagattu characteristically shows association with structures developed due to tectonic stresses preand post dating Cuddapah sedimentation (Bisht et al., 2001, 2011). The basement consists largely of fertile, Closepet equivalent peraluminous, LIL enriched, low Ca, A-Type granites (Srivastava et al., 1992). In the southwestern part, uranium mineralisation occurs in (a) faulted/fractured/brecciated Gulcheru quartzite near Gandi ,(b) along numerous basement fracture zones in younger granitoids around Mulapalle (Umamaheswar et al., 2001 ; Zakaulla et al., 2004), and (c) stratabound uranium mineralisation hosted by carbonate rocks of Vempalle Formation around Tummallapalle (Rai et al., 2002,2010). The basement in the southwestern part of the Cuddapah basin consists of TTG, greenstone belts and late calcalkaline to K-rich granite plutons.
These different types of uranium mineralisation in and around Cuddapah basin show temporal and spatial association with Proterozoic Closepet equivalent granitoids at LambapurPeddagattu-Chitrial-Koppunuru...