||2,03,000 sq km
||Parts of Andhra Pradesh(North of 15° Lat.)
Atomic Minerals Directorate for Exploration and Research,
Department of Atomic Energy, AMD campus,
Survey No.147, Nagaram, Rampally road,
Cherlapally, Keesara Mandal, Hyderabad-500 083.
Fax : 040-29708129
The Region was carved out from Southern Region in 1988.Prior to it, all the investigations were carried out from Southern Region, Bangalore. The Office of the South Central Region was initially started in a rented building in Hyderabad and since 1993 it is located within the premises of AMD Headquarter, Hyderabad.
Broadly following geological domains occupy major part of the region:
(i) Archaean Basement rocks : They comprise (1)Peninsular Granite Gneiss and (2) Eastern Ghat Mobile Belt consisting of charnockites and khondalites in coastal districts of Andhra Pradesh.
(ii) Lower Proterozoic Green Stone Schist Belt such as Nellore Schist Belt, Veligallu-Gadwal Schist Belt and Ramagiri-Penakacherala Schist Belt.
(iii) Middle to Upper Proterozoic rocks :These rocks are exposed in two major geographic domains, such as
(a) Cuddapah Basin comprising sedimentary and igneous rocks of Cuddapah Super group and the Kurnool Super group.
(b) Pakhal Basin comprising Upper Proterozoic sediments deposited in rift related environment along the Godavari belt.
In addition, Middle Proterozoic granites and mafic dyke swarms similar to Closepet granite of Karnataka occur as discrete plutons within the basement rocks.
(iv) Gondwanas (Mesozoic) along Godavari basin : They overlie the Proterozoic rocks of Pakhal basin.
(v) Beach Sand and Inland Placers : They are the part of Quaternary group of rocks. Number of rich beach sand mineral deposits are located in the coastal stretch of Andhra Pradesh.
In addition, very small exposures of Deccan Trap (Mesozoic age) are exposed in the northwestern part of the Region.
Radiometric survey in this part of the country was initiated in the early 50’s. Initially emphasis was given to locate vein type uranium mineralisation in the basement rocks.Some uraniferous occurrences were also located in the Mahabubnagar granite round Wanapurthy during such surveys.
During 1990’s, however, with the changing concept of uranium mineralisation,radiometric surveys led to the discovery of unconformity related uranium mineralisation near the unconformity of fertile Mahabubnagar granite and overlying Srisailam/ Banganapalle quartzite in the northern part of Cuddapah basin. Subsequent detailed investigations including borehole drilling resulted in the delineation of important deposits. These are:
(1) Lambapur : It is located in the Nalgonda district of Andhra Pradesh at a distance of 140 kmSE of Hyderabad. The mineralisation is established over an area of 1.8 km x 0.7 km and is hosted by Srisailam quartzite and the basement granite in the proximity to the unconformity between them. It is a flat lying deposit with a vertical depth of 45m.
(2) Peddagattu :It is lying in very close proximity to Lambapur deposit. The uranium mineralisation at Peddagattu occurs in an exactly similar geologicalset-up and is spread over an area of 4.5km x 1km. Entire mineralisation occurs within a vertical depth of 60m.
Present Thrust areas of Investigations:
Encouraged by the discovery of unconformity-related deposit, radiometric surveys are targeted to locate such type of occurrences in the similar geological environments.A few thrust areas, described briefly, are as follows:
(i) Srisailam-Palnadu basin :In addition to the deposits already established, there are many outliers of Srisailam and Banganapalle quartzite occurring in the Srisailam-Palnadu basins, directly overlying the basement granite.Since the unconformity between them has been established as potential horizon for uranium mineralisation, the radiometric and exploratory drilling are under way in many locations such as Koppunuru in Guntur district and R.V. Tanda in Nalgonda district, etc. Chitrial is another important area.It is located in Nalgonda district of Andhra Pradesh at approximately 130 km south-east of Hyderabad.The mineralisation is confined to the unconformity between the basement granite and Srisailam quartzite.The radioactivity is spread over an area of 50 km2. Exploratory drilling is yet to be taken up here.
(ii) Kurnool basin : Areas have been identified where the Kurnool Supergroup of rocks are projected to overlie the rocks of the Nallamalai fold belt with a pronounced angular unconformity between them.Some of the earlier geochemical surveys have delineated hydrogeochemical anomalies along the Rudravaram line (contact between Nallamalai fold belt and Kurnool Super group rocks).Mineralisation is expected to occur at deeper levels in proximity to the unconformity surface.
(iii) Pakhal basin : Interesting geological set-up exists in Khammam and Warangal district of Andhra Pradesh, where Proterozoic Pakhal group of rocks were deposited over basement granite in rift related environment (Godavari Rift). Gondwana sediments overlie these Proterozoic Supracrustals. Radiometric survey are being carried out in these areas to look for any unconformity related Uranium mineralisation.
All supporting laboratory facilities are being provided from the different laboratories located at AMD Headquarter, Hyderabad.