||4,38,000 sq km
||Bihar, Jharkhand, Orissa, W. Bengal and Sikkim
||Regional Centre for Exploration and Research, AMD Complex, Khasmahal,P.O.: Tatanagar, Dist. East Singhbhum, Jharkhand - 831002.
||Dr. Kalyan Chakrabarti, Regional Director
Ph. : 0657-2299807
Fax : 0657-2297689
Email : email@example.com
Eastern Region was set up during 1959 with headquarter at Kolkata. Subsequently the headquarter was shifted from Kolkata to Jamshedpur in its own premises during 1994. The major thrust of uranium exploration has been in the Singhbhum Shear Zone. The first uranium deposit of the country was established at Jaduguda in 1951. Subsequently, 16 other uranium deposits like Bhatin, Narwapahar, Turamdih, Bagjata, Mohuldih Banduhurang, etc. have been established.
Broad Geological Features
Broadly, following geological domains are exposed in Eastern Region.
(i) Archaean basement gneiss and Proterozoic and other sediments are predominant in the states of Jharkhand, Odisha and West Bengal. The oldest rock (3,800 Ma) found in India (Champua Gneiss) occurs in this geological terrain. The Archaean basement is overlain by Iron Ore Group (IOG) of Odisha and Jharkhand.
(ii) Proterozoic sediments and granites : Lower Proterozoic rocks comprising Singhbhum Group of metasediments and Singhbhum Granite.
-Singhbhum Thrust Belt Lower Proterozoic rocks comprising Singhbhum group of metasediments and Singhbhum granites.
--Dhanjori and IOG Basins– Meso-Archaean to Palaeo-Proterozoic metasediments.
-Eastern Ghat Mobile Belt comprising mostly Khondalites.
-Middle to Upper Proterozoic metasediments of Gangpur, Kolhan and Kunjar basins.
-Rocks of extra peninsular region in the Sikkim Himalaya.
(iii) Gondwana Sediments in Damodar, Mahanadi
(iv) Inland and beach placers of Quaternary period.
URANIUM MINERALISATION AND DEPOSITS
Singhbhum Province was well known during pre-independence period for its mineral wealth, particularly copper deposits.Singhbhum Shear Zone (SSZ), an established uranium belt of the country since 1950, hosts a number of uranium deposits, a few of which are presently under exploitation. Radiometric surveys in this province resulted in identifying hydrothermal vein type of uranium mineralisation hosted in chlorite schists ± apatite, magnetite quartzite at many locations soon after the formation of AMD.
Uranium occurrences are spread all along the 180 km long arcuate SSZ. Exploration by AMD has helped to establish economically viable deposits over several of these occurrences. The important deposits are as follows.
a) Jaduguda : Located in East Singhbhum district, it is the first deposit where mining was undertaken by UCIL in 1967. Mining is still continuing beyond 1,000 meters vertical depth. The mineralisation is associated with conglomerate and chlorite schist of Singhbhum Group. Presently exploration is under progress in the faulted northern block at Jaduguda to establish additional resources. New findings of uranium in the vicinity of Jaduguda have increased the life of this mine.
b) Bhatin : It lies 3 km west of Jaduguda along the Singhbhum Shear Zone. Mineralisation is associated with quartzite and biotite-chlorite schist. Bhatin deposit is being exploited by UCIL since 1986.
c) Narwapahar : It lies 10 km west of Jaduguda along the Singhbhum Shear Zone. The uranium mineralisation, hosted by chlorite-quartz schist spreads over 2,000 meters strike length. This deposit is under exploitation by UCIL since 1995. This is the single largest deposit in SSZ.
d) Turamdih : A cluster of deposits (Turamdih-East, Turamdih-South, Keruadungri) occur in proximity to each other at Turamdih, located nearly 24 km west of Jaduguda. Uranium mineralisation is associated with chlorite-quartz schist. At Turamdih (East) the mineralisation is spread over 2 km X 1 km area and the entire resource occurs within a vertical depth of 200m. Mining of Turamdih (East) deposit is in progress by UCIL. from 2003.
e) Banduhurang:The uranium deposit at Turamdih West is known as Banduhurang deposit. The host rock is chlorite-quartz schist and to a lesser extent, feldspathic schist. The mineralization is spread over 1.2 km strike length and 600m across the strike. The deposit is being exploited by UCIL by open cast mining since 2007.
f) Mohuldih : It is located 5 km west of Turamdih. The host rock is tourmaline bearing quartz schist, quartzite and chlorite quartz schist. Mineralisation is established over 1 km strike length and within a vertical depth of 250m. Mining by UCIL has commenced from April 2012.
g) Bagjata : It is located nearly 25 km southeast of Jaduguda. Uranium mineralisation is hosted by quartz-chlorite-biotite schist. The mineralisation is spread over 450m strike length with a vertical persistence of 260 m. Mining by UCIL commenced in 2008.
h) Banadungri-Singridungri: : It is located to the west of Narwapahar. Uranium mineralization is hosted by sericite-chlorite-quartz schist. The deposit has been established and is currently under advanced consideration for opening of a new mine.
Other smaller uranium deposits along this shear zone, in a similar geological set up are (i) Kanyaluka (ii) Nimdih (iii) Garadih and (iv) Rajgaon.
Apart from uranium, rich resources of xenotime (mineral containing heavy REE) associated with garnetiferous biotite schist of Singhbhum Group of rocks have also been located by AMD at Kanyaluka.
Quartz Pebble Conglomerate hosted uranium mineralization has also been located at a number of places at the base of the Iron Ore Group (IOG) and Dhanjori basins. Important localities are Butgora, Phuljari, Chakri in Jharkhand and Sayamba, Taldih in Odisha.
Uranium exploration: Present thrust areas
Uranium exploration programme in parts of Eastern Region currently gives emphasis for identification of (i) Metamorphite/ vein type uranium deposits in Singhbhum Shear Zone (SSZ), (ii) QPC type mineralization in Meso- to Neoarchean Iron Ore Basin of Bonai sector and Dhanjori Basin in Odisha and (iii) Migmatite-related pegmatoid leucosome hosted uranium mineralization in Garhwa sector of Chhotanagpur Granite Gneissic Complex (CGGC) in Jharkhand. Helium investigation has been initiated in Bakreshwar-Tantloi geothermal fields of CGGC in Jharkhand.
Singhbhum Shear Zone (SSZ) is the known uranium province in the country hosting a number of uranium deposits, a few of which are presently under production by UCIL. The current phase of exploration in SSZ was initiated in 2008-09 with the objective of exploring the extension areas of known uranium deposits in the eastern part of the shear zone and also to explore the western part of the shear zone to convert known occurrences to deposits. Exploration inputs in the current phase have resulted in delineation of deposits at Banadungri-Singridungri area adjacent to Narwapahar deposit and also proved additional resources in the deeper extensions of Narwapahar deposit. A modest deposit has also been established at Bangurdih in the western sector of SSZ. At present, exploratory drilling is being continued in Narwapahar-Banadungri-Singridungri-Garadih sector and Baglasai-Mechua-Jaduguda North sector to delineate the ore bodies and assess the deposits. Exploration has also been initiated in the other potential zones in the eastern sector of SSZ at Pathargora, Purandungri, Khadandungri and Khejurdari. In addition, a new type of deposit is coming up at Kudada, hosted by serpentinised peridotite occurring at a lower stratigraphic level in comparison to the other deposits in the belt.
Quartz Pebble Conglomerate (QPC) The The Singhbhum Craton comprising basement granite with overlying early Proterozoic supracrustals constitute a favourable setting for Quartz Pebble Conglomerate (QPC) type uranium mineralization. Efforts since 1980 led to identification of the QPC type mineralisation in Dhanjori Basin in 1983 followed by the discovery of a number of uraniferous QPC occurrences in Dhanjori and IOG Basins of Singhbhum-Odisha Craton. Significant uraniferous occurrences were identified in Butgora, Phuljhari, Chakri in Dhanjori Basin, Jharkhand, and Sayamba-Taldih and Birtola-Bagiyabahal in Koira-Noamundi Basin, and QPC occurrences overlying Pallahara Gneisses near Mankarhachua, Angul district, Odisha. QPC hosted uranium mineralization is also associated with precious metals like gold, silver and platinum group of elements (PGE).
Basin-wise details of uraniferous QPC areas are as follows:
a) Birtola-Bagiyabahal area: The area is located near the base of the Koira-Noamundi Iron Ore Group sequence along the northwestern margin of Bonai Granitic Complex in Sundargarh district, Odisha. Presence of radioactive QPC has been established around Birtola, Phuljhari Pahar, Balisura, Bagiyabahal and Baratangra areas. The QPCs in the area are both basal and interbedded in nature and are associated with IOG quartzite over an appreciable strike length. Association of gold (Au) with uranium mineralization has enhanced the scope of investigation of the area for other metals.
b) Mankarhachua area: The area is located north of Pallahara, Angul district, Odisha around western margin of Singhbhum Craton. The uraniferous Quartz Pebble Conglomerate horizons are exposed over an appreciable strike length, having best exposures around Mankarhachua village. This horizon is unconformably overlying Pallahara Granite Gneiss along southern margin of the basin. This QPC hosted uranium mineralization is also associated with significant content of precious metals like gold, silver and PGE.
c) Phuljhari-Chakri-Astakoali area: The area is located in the southern and western margins of Dhanjori Basin. A number of potential QPC horizons have been established at Astakoali, Javardih and Butgora areas at the base of Dhanjori Basin.
Chhotanagpur Granite Gneissic Complex (CGGC): The Proterozoic CGGC is an E-W trending sub-arcuate belt of the East Indian Shield that covers approximately 1,00,000 sq km across the states of Chhattisgarh, Jharkhand, Bihar and West Bengal. Uranium mineralisation in the migmatite terrain of CGGC was located at several places in Sonbhadra district of U.P. A small deposit has been established at Naktu area, which is located to the west of Garhwa district of Jharkhand. Based on the analogy of Naktu, radiometric surveys were initiatied in the contiguous areas in Garhwa district in 2016-17 and in the same year uranium mineralisation was located over significant strike length in pegmatoid leucosome in migmatite rocks near Karke. Subsequent surveys in the CGGC has resulted in identification of uranium mineralisation in younger granites and pegmatites at Chundi, besides several other minor occurrences in the CGGC of Garhwa district.
a) Karke area: This area is located about 20 km west of Garhwa. Migmatites dominate the terrain, with abundant leucosomes and melanosomes. The other constituents consist of biotite granite gneiss. Several uraniferous lenses are established over considerable strike length, associated with pegmatoid leucosome in migmatitic rocks. Besides, several pegmatitic intrusions along the migmatite zone and in granite gneisses are also radioactive.
b) Chundi area: This area is located about 1.5 km SW of Karke occurrence. Porphyroblastic granite gneiss, granite gneiss, pink granite, basic bodies, quartzite and pegmatite are the main lithounits exposed. Pink granite is younger and occurs as intrusive within the gneisses. The uranium mineralisation is associated with granite and pegmatitic intrusions, and significant strike extension has been established.
Helium investigations in Bakreshwar-Tantloi: Bakreshwar-Tantloi area is located in the northeastern part of CGGC and is a well-known geothermal province. The area exposes granite gneiss with aplite, vein quartz and basic intursives. Since the early 1970s hot water springs of Bakreshwar and Tantloi, located on the eastern continuation of Narmada Son Lineament Zone, are known to emanate appreciable quantity of helium (upto 1.8%). Past investigations by various organisations including AMD have revealed that the area around Bakreshwar and Tantloi have the potential to host helium gas reserve. Soil gas radon emanometry using closed circuit technique has indicated two significant trends in Bakreshwar - i) NE-SW and ii) N-S, while at Tantloi, the radon anomalies trend N-S and E-W. Radon surveys are being continued in adjoining areas which would help in identifying the extension of the subsurface fracture zones. Gas samples from the thermal springs and soil have analysed significant helium values.
The Region is equipped with following laboratory facilities.
Remote Sensing Laboratory