||5,49,000 sq km
||Rajasthan,Gujarat and parts of Madhya Pradesh
||Regional Centre for Exploration and Research,AMD Complex,Sector-5 Extension,Pratap Nagar,Sanganer,Jaipur - 302033
||V. Natarajan, Regional Director
Ph : 0141-2793598
Fax : 0141-2795488
e-mail : firstname.lastname@example.org
The Region was set up initially as North Western Region during 1988 when it was carved out of Northern Region. It was housed in rented accommodations till recently and in 2004 a new office-laboratory building has been completed. The Region has residential quarters catering to the requirements of officers and staff.
The following are the broad geological domains of the Western Region.
(i) Archaean Basement Rocks ( >2500 Ma) :
The Banded Gneissic Complex (BGC) with enclaves of amphibolites and intrusive granitoids such as Untala granite, Gingla granite,Berach granite etc. which form the basement for Aravalli and other younger meta-sediments.
(ii) Lower Proterozoic Aravalli Supergroup rocks:
The Aravalli Supergroup of rocks, which were deposited in rift related basins, form the most prominent geological feature. The ravallis consist of basalts, quartzites, carbon phyllites, marbles, greywackes,conglomerates, arkoses etc. These rocks are well known for their intricate folding and multiple deformations. Some synkinematic granitic bodies e.g. Darwal granite, Amet granite is emplaced into it
(iii) Middle to Upper Proterozoic Delhi Supergroup rocks and their equivalents:
The succeeding Delhi Fold Belt comprises limestones, quartzite, arkose,quartz- mica schists and contemporaneous volcanic rocks. They were deposited mostly in the northeastern part of Rajasthan. They are also intricately folded with several granitic emplacements.
The Champaner Group of rocks were deposited along the southern fringe of Aravallis during upper Proterozoic period. Godhra granite was emplaced into them synkinematically.
(iv) Neo Proterozoic rocks of Western Rajasthan:
A number of younger (800 m.y.) intrusive/ extrusive bodies such as Malani, Angor, Siwana, Jalore occur in the western part of Rajasthan. Over them are deposited Marwar Supergroup of rocks comprising mica schists, phyllites and quartzites.
Besides,Deccan Trap of Mesozoic age and Vindhyan rocks of Upper Proterozoic age occupy small parts of the Region.
A major part of radiometric surveys were directed to locate vein and other deposits in Proterozoic basins. Some of the uranium deposits identified during the period are :
It is located in Udaipur district, Rajasthan. The host rocks are carbonaceous phyllites and dolomites of Aravalli Supergroup.This deposit is divided in Umra main and Umra north-east. It is a vein type of deposit occurring over 650m strike length in Umra main and 750m in Umra north-east and within a vertical depth of 315m and 400m respectively.This area is being re-investigated from the standpoint of unconformity type of uranium mineralisation.
It is located in Sikar district, Rajasthan and lies along the albitite line,a 300km NNE-SSW trending zone of extensive albitisation. The host rocks are albitised biotite schists of the Delhi fold belt.It is albitite type of deposit occurring over 1850m strike length and within a vertical depth of 500m. Exploration is in progress here.
Radioactivity associated with Quartz Pebble conglomerates (QPC) overlying Banded Gneissic Complex (BGC) has been located at Kharbar in Udaipur district, Rajasthan. This occurrence has now been taken up for detailed studies.
In addition, a number of columbite-tantalite,beryl,lepidolite-bearing pegmatite occurrences are located along Rajasthan mica belt at Deoria, Sangwa, Lakhola, Soniana and Danta-Bhunas.
The present thrust of uranium exploration is mainly in the following three geological environments
(a) Albitite Line : Along the Albitite line, which coincides with the major fold axis of Delhi fold belt, radiometric survey and exploration are being carried out to discover more occurrences similar to Rohil.
(b) Jahajpur basin : Survey and exploration are also concentrated in the Lower Proterozoic rocks of Jahajpur basin overlying the Hindolis of BGC in Bhilwara district of Rajasthan. High grade uranium mineralisation, along with traces of gold and silver, was recently discovered associated with banded calc arenaceous unit of the Jahajpur basin.
(c) The unconformity contact of the Neo Proterozoic Marwar Supergroup rocks and the Lower Proterozoic Aravalli - Delhi metasediments is considered as a potential horizon for uranium mineralisation. Programme has also been drawn up to look for unconformity related uranium mineralisation in this set up.
(d) Quartz Pebble Conglomerate:Radioactivity in Lower Aravalli QPC is known since 1960 though majority of samples were thoriferous. Radioactivity due to uranium was located in Lower Aravalli QPC during 1974-75 at Parsad. Later radioactivity was also recorded in migmatites and biotite schist in basement below the conglomerates near Kharbar. Thus, the area around Sarara inlier has potential for locating QPC type uranium mineralization in the Aravalli metasediments and also epigenetic mineralization along faults traversing the basement.
The Region has the following analytical laboratories