Current Science

Rajeev Bidwai ¹, S. Srinivasan ¹, L. K. Nanda ¹, Atanu Banerjee ¹, P. N. Bangroo ¹, A. K. Rai ², P. S. Parihar ²

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Western Region, Jaipur 302 030, IN
2 Atomic Minerals Directorate for Exploration and Research, Hyderabad 500 016, IN

Abstract

No Abstract.

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Rajeev Bidwai , S. Srinivasan , L. K. Nanda , Atanu Banerjee , P. N. Bangroo , A. K. Rai , P. S. Parihar

Abstract

No Abstract.

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U. P. Sharma ¹, S. Shukla ¹, P. K. Sinha ¹, R. K. Purohit ¹, A. Majumdar ¹, A. K. Rai ²

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, AMD Complex, Civil Lines, Nagpur 440 013, IN
2 Atomic Minerals Directorate for Exploration and Research, AMD Complex, Begumpet, Hyderabad 500 016, IN

Abstract

No Abstract.

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G. S. Yadav ¹, A. Muthamilselvan ², T. S. Shaji ³, L. K. Nanda ⁴, A. K. Rai ⁴

Affiliations
1 Jamshedpur 831 002, IN
2 Center for Remote Sensing, Bharthidasan University, Tiruchirappalli 620 023, IN
3 Thiruvananthpuram 659 012, IN
4 Hyderabad 500 016, IN

Abstract

No Abstract.

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A. K. Rai ¹, S. Tripathy ¹, S. C. Sahu ²

Affiliations
1 School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Bhubaneswar 751 007, IN
2 India Meteorological Department, Bhubaneswar 751 020, IN

Abstract

The northeastern part of the Indian Ocean, i.e. the Bay of Bengal (BoB) is located near some of the most complicated tectonic zones on the Earth. An earthquake of magnitude ∼6.0 occurred on 21 May 2014 near the coast of Odisha. Occasional moderate to large earthquakes in BoB highlight the need to study precise hypocentre locations, and focal mechanisms to understand the cause of intraplate seismicity in BoB.It is also important for seismic hazard and tsunami risk evaluation along the eastern coast of India. We present an analysis of the digital data of this earthquake recorded by regional and global networks of seismic stations. Our analysis of travel-times of P- and S-waves indicates that the epicentre of the earthquake is located between the Eighty Five East and Ninety East ridges. The focus of this earthquake was at a depth of ∼61 km, well below the lower boundary of the oceanic crust. The focal mechanism determined by modelling long period P- and SH-waveforms suggest an strike-slip motion along a NW-SE or NEE-SWW-directed fault or fracture. We interpret that the upper part of the BoB lithosphere is abnormally strong and brittle.

Keywords

Earthquake Location, Focal Mechanism, Intraplate Seismicity, Tectonic Zones.

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A. Yugandhara Rao ¹, K. Vijay Raj ², O. P. Yadav ², L. K. Nanda ³, A. K. Rai ³, P. S. Parihar ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Vishakapatnam 530 007, IN
2 Atomic Minerals Directorate for Exploration and Research, Jaipur 302 033, IN
3 Atomic Minerals Directorate for Exploration and Research, Hyderabad 500 016, IN

Abstract

Magnesium-bearing calcretes of soft-gritty and hard pan varieties containing uranium concentrations from 16 to 74 ppm with <10 ppm of thorium are located along the Saraswati palaeochannel at Khemasar village, Churu district, Rajasthan. The uraniumbearing calcretes are exposed over an areal extent of 300 m × 200 m with thickness of up to 2 m in an interdunal depression. The silty sand layer occurring below the calcrete horizon suggests that it is a valley-fill calcrete, deposited along a palaeochannel. This occurrence of uraniferous Mg-calcrete in the Saraswati river palaeochannel opens up a large area for uranium exploration in the calcrete environment of Thar Desert. These calcretes are composed of 15.94% to 25.39% CaO, 7.15% to 22.39% MgO and Sr/Ba ratio up to 66.98. There is a positive correlation of U with Sr/Ba and MgO. The high Sr/Ba ratio and MgO indicate water of saline nature and high rate of evaporation. Ephemeral centripetal drainage mixing with the dissected palaeochannel waters and groundwaters, under arid climatic conditions might have resulted in the formation of this kind of uranium-bearing calcrete in fluvio-lacustrine environment.

Keywords

Fluvio-Lacustrine Environment, Khemasar, Magnesian Calcrete, Surficial Type Uranium.

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G. S. Yadav ¹, U. K. Pandey ², S. L. Aravind ³, P. K. Panchal ³, A. S. Venkatesh ⁴, P. R. Sahoo ⁴, A. K. Chaturvedi ², A. K. Rai ², P. S. Parihar ²

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Jamshedpur 831 002, IN
2 Atomic Minerals Directorate for Exploration and Research, Hyderabad 500 016, IN
3 Atomic Minerals Directorate for Exploration and Research, Jaipur 302 030, IN
4 Department of Applied Geology, Indian Institute of Technology (Indian School of Mines), Dhanbad 826 004, IN

Abstract

Uranium mineralization in Bichun area, Jaipur district, Rajasthan, India is hosted by albitites within the Banded Gneissic Complex (BGC). Detailed mineralogical and EPMA studies reveal the presence of davidite along with brannerite and uraninite. The U-Pb concordia upper intercept age of 933 ± 13 Ma and Pb-Pb isochron age of 930 ± 4 Ma, on pure davidite fractions indicate the timing of uranium mineralizing event to be ca. 930 Ma. The timing of uranium mineralization can be correlated with the Grenvillian orogeny (ca. 1000 Ma). The Sm-Nd model age (T_DM) of daviditeis varies from 1851 to 2200 Ma with ε_{Ndi(930 Ma)} ranging from -10.7 to -15.5 which shows that the Palaeoproterozoic rocks with crustal component (either within BGC or basement granite) are the source for uranium.

Keywords

Albitite Zone, Davidite, Geochronology, Orogeny, Uranium Mineralization.

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