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The Region was carved out from Southern Region in 1988. South-Central Region was initially started in a rented building in Hyderabad and between 1993 to 2016, it was functioning within the premises of AMD Headquarters, Begumpet, Hyderabad. It was shifted from headquarters, Begumpet to Cherlapally area, Hyderabad in May 2016.
Broadly following geological domains occupy major part of the Region:
(i) Archean Basement rocks: These comprise Peninsular Granite Gneiss, Karimnagar Granulite Belt and Eastern Ghat Mobile Belt. Closepet equivalent granites occur as discrete plutons within the basement complex. Besides, number of younger intrusive also occur in the north-western part of the Cuddapah basin. Number of mafic dyke swarms intrude the basement complex.
(ii) Lower Proterozoic Greenstone Schist Belts: Major Schist belts are Nellore Schist Belt, Veligallu-Gadwal Schist Belt, Ramagiri-Penakacherala Schist Belt and Peddavoora Schist Belt.
(iii) Middle to Upper Proterozoic rocks: These rocks are exposed in two major geographic domains, viz. (1) Cuddapah Basin comprising sedimentary and igneous rocks of Cuddapah Supergroup and the Kurnool Supergroup and (2) Pranhita-Godavari Basin comprising sediments of Pakhal Supergroup. Besides, sediments of Bhima Basin also occur in the western part.
(iv) Gondwanas (Mesozoic) along Godavari Basin: Along the Godavari Basin, the Mesozoic Gondwana sediments overlie the Proterozoic rocks of Pakhal Supergroup.
(v) Beach Sand and Inland Placers: These form part of Quaternary Group of rocks. Number of rich beach sand mineral deposits are located along the coastal stretch of Andhra Pradesh.
Small exposures of Deccan Trap (Mesozoic age) occur in the north-western part of the Region.
Srisailam sub-basin: During 1990s, with the evolving concept of unconformity type uranium deposits worldwide, radiometric surveys in the environs of Cuddapah Basin, led to the discovery of uranium mineralisation close to the unconformity between Paleoproterozoic fertile Mahbubnagar (Closepet equivalent) granite and overlying quartzite of Srisailam Formation. The Srisailam Formation rocks, the youngest sediments of Cuddapah Supergroup, are exposed in the Srisailam sub-basin, having an area of 5,000 sq. km. Detailed exploration in parts of the sub-basin by drilling led to delineation of well-established unconformity related uranium deposits at Lambapur, Peddagattu and Chitrial. In these uranium deposits, the Srisailam Formation is represented by a basal pebbly-gritty sequence followed upward by intercalated grey shale-quartzite with massive quartzite layer at the top.
Important uranium deposits are summarized below:
Lambapur: Unconformity related uranium mineralisation has been established in two ore bodies over an outlier of Srisailam Formation having dimension 1.8km x 0.70km. Mineralisation is largely hosted in the basement granite and partly in the altered basic dyke intrusive into the basement and in gritty quartzite of Srisailam Formation. The ore bodies have a maximum depth of 45m. A total of 1450 tonnes U3O8 has been established
Peddagattu: This deposit occurs ~1km south of Lambapur deposit and has similar geological and mineralisation set-up as that of Lambapur. Eight uranium-mineralized blocks occur in an outlier of Srisailam Formation exposed over 10km x 2km. All the ore bodies are confined to a maximum depth of 60m. A total of 7585 tonnes U3O8 has been proven
Chitrial: The deposit is located about 25km southwest of Peddagattu. The deposit occurs in an outlier of Srisailam Formation. It has similar geological and mineralisation set-up as that of Lambapur-Peddagattu uranium deposits. In Chitrial, the ore bodies have been established having considerable strike length with depth range of 30m-90m in western and eastern sectors. A total of 9515 tonnes U3O8 has been established
Similar other outliers of Srisailam quartzite spread over total areal extent of 83 sq. km have been recognised for detailed exploration by drilling to augment additional uranium resources.
Palnad Sub-basin: Palnad sub-basin, which is equivalent of the Kurnool sub-basin with an aerial extent of 3,400 sq. km is exposed in the northern part of Cuddapah Basin. The unconformity contact between Banganapalle Quartzite and basement granite is a potential horizon for uranium mineralisation. A small uranium deposit has been located at Koppunuru, Guntur district, Andhra Pradesh near the unconformity. Exploration is underway in similar geological setting in Sarangapalli area in Guntur district, Andhra Pradesh.
Unconformity proximal uranium mineralisation at Koppunuru is largely associated with Banganapalle quartzite. Uranium ore bodies in the form of three sub-horizontal lodes occur in the Banganapalle quartzite, 5-40m above the unconformity and along the unconformity contact transgressing into the Basement granite. A total of 2761 tonnes U3O8 has been proved in the deposit.
(i)Kappatralla area, Kurnool district, Andhra Pradesh: Unconformity proximal uranium mineralization has been identified in one outlier at Kappatralla lying 35km west of Kurnool located in the western margin of Cuddapah Basin. The uranium mineralisation occurs along the contact of Paleo-proterozoic granite basement and overlying quartzite of Gulcheru Formation. Exploration in the entire outlier (4.50 sq.km) is planned to augment the resource.
(ii) Rudravaram line: The Rudravaram Line marks the contact of undisturbed sediments of Kurnool Group and folded and deformed sediments of Nallamalai Group. The area closure to the eastern margin of the Palnad sub-basin in the vicinity of Rudravaram line, wherein the undeformed Kurnool Group of rocks overlie the folded and deformed sedimentary rocks of Nallamalai Fold Belt, represents a potential zone for hosting unconformity type uranium mineralization. Several hydro-uranium and Rn-in water anomalous zones have been delineated over the Kurnool Group of rocks. Several conducting bodies along structural loci have been identified by ZTEM techniques. Uranium mineralisation is expected to occur at deeper levels in proximity to the unconformity surface.
(iii) Sarangapalli area: Sarangapalli area, located in the northern part of Palnad sub-basin, exposes Neo-Proterozoic Banganapalle Quartzite and Narji Limestone of Kurnool Group unconformably overlying Closepet equivalent granite in Guntur district, Andhra Pradesh. Subsurface exploration commenced in the area in 2018 and indicated fairly good uranium potential. Small uranium resource has been inferred in the area over an area of ~2km x 500m. Primary uranium minerals (coffinite, pitchblende and uraninite) occurring along the micro fractures and weak planes have been identified. Drilling is in progress to delineate extension of ore body.
National Core Library, preserving borehole cores of various uranium deposits of India was established in 2020 at South Central Region. Core scanning facility was established to preserve geological data in the digital format.
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