Refine your search
Collections
Co-Authors
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Kak, S. N.
- Discrete Selenide Phases from the Uraniferous Mahadek Sandstones of Domiasiat and Wahkyn South, West Khasi Hills District, Meghalaya
Abstract Views :200 |
PDF Views:171
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy 'Begumpet, Hyderabad - 500 016, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Shillong, Meghalaya, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Tatanagar, Jamshedpur, IN
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy 'Begumpet, Hyderabad - 500 016, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Shillong, Meghalaya, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Tatanagar, Jamshedpur, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 59, No 6 (2002), Pagination: 571-574Abstract
Occurrences of discrete selenide phases in the geological environment are rather rare and are confined to a few sulphide deposits and sandstone-type uranium deposits such as those of the Colorado plateau, USA. The occurrence of discrete selenide phases viz., clausthalite (PbSe), ferroselite (FeSe2) and Co-penroseite (CoNiCuSe2) are reported for the first time from the Uraniferous Mahadek sandstones of Domiasiat and Wahkyn South, West Khasi Hills District, Meghalaya. The selenide phases are associated with pyritiferous organic matter, pitchblende and other ore minerals such as marcasite and sphalerite.Full Text
- Late Cretaceous - Tertiary Sediments and Associated Faults in Southern Meghalaya Plateau of India Vis-a-Vis South Tibet: their Interrelationships and Regional Implications
Abstract Views :167 |
PDF Views:196
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, IN
2 Geological Survey of India, Sector E, Aliganj, Lucknow-226024, IN
3 Geological Survey of India, Kolkata, IN
1 Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, IN
2 Geological Survey of India, Sector E, Aliganj, Lucknow-226024, IN
3 Geological Survey of India, Kolkata, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 58, No 2 (2001), Pagination: 182-184Abstract
No Abstract.Full Text
- Depositional Environment and Age of Mahadek Formation of Wahblei River Section, West Khasi Hills, Meghalaya
Abstract Views :272 |
PDF Views:2
Authors
Affiliations
1 1 - 10- 15311 56, AMD Complex, Begumpet, Hyderabad - 500 016, IN
1 1 - 10- 15311 56, AMD Complex, Begumpet, Hyderabad - 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 60, No 2 (2002), Pagination: 151-162Abstract
Depositional conditions deduced from field, petrography and textural studies show that Lower Mahadek sediments (LMS) are of fluvial and Upper Mahadek sediments (UMS) are of marine origin. A hard lateritic ground represents the discontinuity surface between the fluvial, reduced uranium-mineralized facies (LMS) and the marine, oxidized facies (UMS). The change in facies, together with the pyroclastics discovered recently, represents a distinct time gap within the Mahadek sedimentation not reported earlier and is related to Sylhet volcanism. The pyroclastics and discontinuity surface indicate that the Lower Mahadek sediments may range from late Jurassic to early Cretaceous and Upper Mahadek sediments are most probably late Cretaceous, the intervening period being represented by the deposition and denudation of pyroclastics. This study shows that the Lower Mahadek are volcanoclastic sediments and brings out an unconformity within the Mahadek Formation of Meghalaya plateau.Keywords
Discontinuity Surface, Pyroclastics, Mahadek Formation, Meghalaya.
- Petrography and Geochemistry of Uranium Mineralised Precambrian Granitic-Pegmatitic Rocks of Mawlait, West Khasi Hills District, Meghalaya
Abstract Views :208 |
PDF Views:0
Authors
Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Jamshedpur - 831 002, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Nagpur - 440 001, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 016, IN
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Jamshedpur - 831 002, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Nagpur - 440 001, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 74, No 5 (2009), Pagination: 639-645Abstract
During radiometric investigation at Mawlait, significant uranium mineralisation (0.024-0.22%U3O8) was located mainly within the small pegmatite (garnet bearing quartzofeldspathic rock), which are locally segregated within migmatite at Umiang River section. Pink granite and granite gneisses are the dominant lithounits of the study area showing fertile character and spotty radioactivity at several places. Radioactivity in these rocks is mainly contributed by discrete uraninite grains along with some zircon and xenotime. Granites are peraluminous, low-Ca in nature and their geochemical signatures suggest derivation from a felsic source. Discriminant diagrams using Rb, Nb and Y indicate 'within plate' to 'volcanic arc' nature of the rock. The uraniferous pegmatitic veins within migmatite appear to have formed due to localised metamorphic segregation during late stage of anatexis. Petromineralogical and geochemical studies suggest that the uranium mineralisation in granitic-pegmatitic rocks of the area is mainly syn-magmatic type.Keywords
Pegmatite Veins, Granites, Uranium Mineralisation, Mawlait, Meghalaya.References
- BARKER, F. (1979) Trondjemites: definition, environment and hypothesis of origin. In: F. Barker (Ed.), Trondjemites, dacites and related rocks. Elsevier, Amsterdam, pp.1-12.
- BARKER, F. and ARTH, J.G. (1976) Generation of trondhjemite tonalitic liquids and Archean bimodal trondhjemite - basalt suites. Geology. v.4, pp.596-600.
- BROWN, G.C., THORPE, R.S. and WEBB, P.C. (1984) The geochemical characteristics of Granitoid in contrasting areas and comments on magma sources. Jour. Geol. Soc. London, v.141, pp.413-426.
- DHANA RAJU, R., PANEER SELVAM, A. and SINHA, R.M. (1996) Petrology and Geochemistry of the Neoproterozoic South Khasi Batholith and related granitoids in the Khasi Hills district, Meghalaya and their bearing on Uranium Mineralisation. Expl. and Res. Atomic Minerals, v.9, pp.73-89.
- EL BOUSEILY, A.M. and EL SOKKARY, A.A. (1975) The relation between Rb, Ba and Sr in granitic rocks. Chem. Geol., v.16, pp.207-219.
- GSI (1977) Geology of Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura. Miscellaneous Publication, no.30, 124p.
- GHOSH, S., CHAKRABORTY, S., PAUL, D.K., BHALLA, J.K., BISHUI, P.K. and GUPTA, S.N. (1994) New Rb-Sr isotopic ages and geochemistry of granitoids from Meghalaya and their significance in middle-to-late Proterozoic crustal evolution. Indian Minerals, v.48, No.1&2, pp.33-44.
- GOLANI, P.R. (1989) Sillimanite - Corundum deposits of Sonapahar, Meghalaya, India: A metamorphosed Precambrian Palaeosol. Precambrian Res., v.43, pp.175-189.
- GOVINDA RAJU, K. (1989) 1989 compilation of working values and samples description for 272 standards. Geostandard Newsletter, Special Issue, v.13, pp.01 (Appendix).
- JAHNS, R.H. and BURNHAM, C.W. (1969) Experimental studies of pegmatite genesis: I. A model for the derivation and crystallization of granitic pegmatites. Econ. Geol., v.64, pp.876-901.
- KRAUSKOPF, K. (1982) Introduction to Geochemistry. 2nd Ed. Mcgraw Hill Book Company, New York, 611p.
- MANIAR, P.D. and PICCOLI, P.M. (1989) Tectonic discrimination of granitoids. Geol. Soc. Amer. Bull., v.101, pp.635-643.
- O'CONNOR, J.T. (1965) A classification of quartz rich igneous rock based on feldspar ratio. U.S. Geol. Surv, Prof. Paper, 525-B, pp.79-89.
- PEARCE, J.A., MORRIS, N.B.W. and TINDLE, A.G. (1984) Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Jour. Petrol., v.25, pp.956-983.
- ROGERS, J.J.W. and GREENBERG, J.K. (1990) Late-orogenic, postorogenic and anorogenic granites: distinction by major elements and trace elements chemistry and possible origins. Jour. Geol., v.98, no.3, pp.291-309.
- TAYLOR, S.R. (1965) The application of trace elements data to problems in petrology. In: L.A. Ahren, F. Press, S.K. Runcorn and H.C. Urey (Eds.), Physics and Chemistry of the Earth. Pergamon Press, London, v.6, pp.123-213.
- TRACY, R.J. and MCLELLAN, E.L. (1985) A natural example of the kinetic controls of compositional and textural equilibrium. In: A.B. Thompson and D.C. Rubie (Eds.), Metamorphic reactions, kinetics, textures and deformations. Advances in physical Geochemistry. Spinger-Verlag. pp.118-137.
- VISWANATHAN, S. (1993) Critical element ratio maps of granitic and migmatitic areas (CERMOGAMA): A supplement to radiometric and magnetic maps (ASTRAMA). Workshop on 'High Sensitivity Airborne Radiometric and Magnetic Surveys' AMD, Hyderabad, pp.1-7.
- WHALEN, J.B., CURRIE, K.L. and CHAPPELL, B.W. (1987) A-type granites: geochemical characteristics, discrimination and petrogenesis. Contrib. Mineral. Petrol., v.95, pp.407-419.