Ramesh Kumar K.,Atomic Minerals Directorate for Exploration and Research |
Pande D.,Atomic Minerals Directorate for Exploration and Research |
Misra A.,Atomic Minerals Directorate for Exploration and Research |
Nanda L.K.,Atomic Minerals Directorate for Exploration and Research
Journal of the Geological Society of India | Year: 2011
The Didwana playa, the second largest playa in the eastern part of the Thar desert, is 5.6 km long and 2.4 km wide and supports commercial salt production. The thickness of lake sediment package is reported to be 20 m and comprises fine grained clays and silts, with abundant calcite, gypsum, and halite, associated with hypersaline water. Isolated hills of graphitic phyllite and quartzite are seen on the western side of the lake. During the course of investigations for uranium in surficial environment of semi-arid terrain of Rajasthan, ground water sampling defined a NE-SW trending uranium halo encompassing the Didwana playa. Subsequent sampling of unlined dug wells, up to water table in central part of the playa, indicated uranium values up to 190 ppm and 2072 ppb in lake sediments and brine respectively. These values are of the order of 21 ppm and 192 ppb towards the southwestern periphery of the lake. The average uranium content, as inferred from 12 samples in the central part of the lake, is around 60 ppm over a thickness of 5 m. It appears that the uranium is loosely bonded to the sediments in amorphous form and is, hence, easily leachable. Samples of brine (n=10), from both the central and southwestern portions of the lake, analysed high (1,67,500-3,00,000 mg/l) TDS, HCO 3- (1128-8395 mg/l), and SO4 (30,536-88,000 mg/l). These are of alkaline (pH: 7.2-9.3) and reducing (Eh: -200 to -340 mV) nature. Under these Eh-pH conditions below the groundwater table, and for such uranium bearing groundwater, precipitation of primary uranium is expected. It is, therefore, modelled that uranium in lake sediment package above water table is concentrated by evaporation process and by chemical reduction below the water table. As the sampling is so far confined to zones above water table, the above possibility is still to be examined. Features like high intrinsic uranium in lake (playa) sediments as well as groundwater, the alkaline and reducing nature of groundwater, which may facilitate precipitation of primary uranium below water table, and the large extent of the lake sediments (10 sq km × 20 m thickness) make the Didwana Lake, a potential candidate for hosting a surficial-type uranium occurrence of significance, for which samples below water table need to be generated. These studies are expected to establish the lake sediment environment in semi-arid tracts of Rajasthan as a new target horizon for locating surficial-type uranium mineralisation in India. © 2011 Geological Society of India.
Laxman Singh K.,Environment Protection Training and Research Institute |
Sudhakar G.,Environment Protection Training and Research Institute |
Swaminathan S.K.,Environment Protection Training and Research Institute |
Muralidhar Rao C.,Atomic Minerals Directorate for Exploration and Research
Environment, Development and Sustainability | Year: 2014
Uranium mill tailings are the crushed rock residues of the uranium extraction process from ores. The tailings effluent and tailings solids from the mill are discharged as slurry to a waste retention pond, called tailing pond. Natural radionuclides’ and trace metals are present in mine tailing/soil in varying concentrations, and some of these are found in elevated concentrations in uranium waste tailings. Uranium mine tailing ponds at Jaduguda and Turamdih receive waste from ores mined at the six mine stations at Jharkhand state, India. A study was undertaken to evaluate the potential of native plant species for the phytoremediation of these site. Three sampling stations were selected at Jaduguda (TP1, TP2, TP3) and Turamdih and at the downstream of effluent treatment plant. pH, electrical conductivity, metals (12-Al, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Cd, Pb) and radionuclides’ (3-Co, Sr and U) were analyzed using inductively coupled plasma mass spectrophotometry. From the analysis, four elements—Al, Mn, Fe and U—were found to be much higher in concentration in water with range (mg/kg) of 0.02–2.38, 0.30–31.67, 0.00–0.75 and 0.03–5.50, respectively, and 10 elements—of U, Mn, Al, V, Fe, Ni, Cu, Zn, Co and Se—were found to be higher in concentrations in soils with range (mg/kg) of 22–99, 1,072–8,065, 14,053–21,213, 66–139, 15,163–44,640, 149–240, 135–350, 89–191, 34–140 and 12–122, respectively. Among them, U and Mn were identified as predominant contaminants. Out of all the native plants, 21 species were screened for phytoaccumulation and transfer factor study. P. digitalis (for Al, V, Ni and Co), E. ferox (for Mn and Cu), A. indica (for Fe), B. vitisidae (for Zn), P. hydropiper (for Se) and S. spantanium (for U) were identified for hyper-accumulation, and A. indica (for Al, Co, Se and U), C. bunplandianus (for Mn, Fe, Ni and Cu), E. ferox (for V) and C. procera (for Zn) were listed for non-accumulation of respective contaminant. Besides this, taking consideration of the parameters such as shallow-rooted plant species, easy to adapt, growth, harvest and biomass production and simultaneous accumulation of multiple contaminants, following plants were found to be candidate species for phytoremediation of tailing ponds of uranium mines: For hyper-accumulation: P. vittata (can accumulate Al, V, Ni, Co, Se and U simultaneously) followed by P. digitalis, C. compressus and S. spantanium. For non-accumulation: C. bunplandianus (can non-accumulate Al, Mn, Fe, Ni, Co, Cu, Zn, Se and U simultaneously) followed by B. moneri, C. procera and A. indica. © 2014, Springer Science+Business Media Dordrecht.
Sinha K.K.,Atomic Minerals Directorate for Exploration and Research |
Pandey P.,Atomic Minerals Directorate for Exploration and Research |
Bhairam C.L.,Atomic Minerals Directorate for Exploration and Research |
Parihar P.S.,AMD Inc
Journal of the Geological Society of India | Year: 2011
In the western part of Bundelkhand massif, a caldera with intra-caldera sediments, known as Dhala Formation, occurs as an outlier in and around Mohar village of Shivpuri district, Madhya Pradesh. For the first time, occurrence of peperite is being reported from the basal part of the Dhala sediment. Two types of peperites have been recognized: blocky and fluidal or globular with variable morphology. In peperitic zones, features like soft sediment deformations, presence of sediment into the rhyolite along cracks, vesiculation of the sediments and other evidences suggestive of sediment fluidization are some definite characteristics of interaction of hot magma with wet sediments forming peperite. The occurrence of peperites reflects the contemporaniety of deposition of the Dhala sediments and volcanism, which is well in accordance to the volcanic origin of Dhala structure. Further, the nature of unconformity between the Dhala and overlying Kaimur which is characterized by merely a few centimeter thick pebbly/conglomeratic bed does not appear to represent a large hiatus as expected between the Semri and Kaimur of Vindhyan Supergroup. So, the contemporaniety of the Dhala Formation (at least the lower part) as reflected by occurrence of peperites, coupled with the available age of the rhyolite and the nature of the unconformity between the Dhala and overlying Kaimur provide convincing evidence to correlate the Dhala Formation with the Lower part of the Kaimur and unlikely with the Semri Group or Bijawar as proposed earlier. © 2011 Geological Society of India.
Bhattacharya D.,Atomic Minerals Directorate for Exploration and Research |
Joshi G.B.,Atomic Minerals Directorate for Exploration and Research |
Sharma R.,Atomic Minerals Directorate for Exploration and Research
Journal of the Geological Society of India | Year: 2011
Several small lensoidal bodies of felsic volcanics are exposed in a curvilinear pattern within the brecciated granitoids of Bundelkhand Gneissic Complex (BGC) at Mohar. Sub-surface data reveals extensive presence of these felsic volcanics below the sediment of Vindhyan Supergroup. It occurs like a sheet with thickness varying from 12 m to 134 m. Its lateral extent has been traced upto 4.8 km. Multiple flows of felsic magma are identified based on colour, granularity, cross cutting relations and cyclic distribution of multiple vesicular bands along the entire thickness of felsic magma. The felsic rock contains upto 13.21% K2O. Chemical composition of these felsic volcanics varies across the column. Petrographically and chemically all these felsic volcanics are identified as rhyolite or rhyolite tuff. Significant uranium mineralisation of 0.0165% eU3O8 average grade has been intercepted for 11.10 m thick with <0.005% ThO2 within the felsic rock. Radiometric assay of a mineralised intercept (15 cm length) has revealed up to 0.15% U3O8 with disequilibrium in favour of parent. Uranium occurs as disseminated grains of coffinite - (Y) associated with pyrite, chalcopyrite, galena, molybdenite, hematite, fluorite, anglesite and cerrusite. Mineral assemblage and mode of occurrence of the uranium and other minerals in the host rock indicates its hydrothermal nature. This is the first reported uranium occurrence from the volcanogenic environment of Bundelkhand. © 2011 Geological Society of India.
A novel method of synthesizing solid phase adsorbent silica modified with xylenol orange: Application for separation, pre-concentration and determination of uranium in calcium rich hydro-geochemical samples and sea water-Part 1
Cyriac B.,Atomic Minerals Directorate for exploration and Research |
Balaji B.K.,Atomic Minerals Directorate for exploration and Research
Microchimica Acta | Year: 2010
A novel, single-step route has been developed for the synthesis of solid phase adsorbent silica modified with xylenol orange. The addition of cationic surfactant cetyl tri-methylammonium bromide during the synthesis of the adsorbent supports the formation of a stable coating of xylenol orange on silica. The adsorbent showed no signs of degradation in contact with organic solvents and with solutions of varying pH between 1 and 9. This adsorbent has been used for separation and pre-concentration of uranium from hydro-geochemical samples with high calcium content and from sea water. Quantitative sorption of uranium was observed above pH 3 and complete desorption can be achieved using 0.2 M sodium pyrophosphate solution. The uranium content in the extract was determined by laser fluorimetric technique. The equilibration time is 30 min. The sorption capacity of the adsorbent for uranium is 10 mg g -1. An enrichment factor of 50 was obtained by this procedure taking 500 mL of sample solution. Uranium concentrations down to 0.05 ng mL -1 can be determined after pre-concentration using this method. The relative standard deviation at an 0.1 ng mL -1 level is ±15%. © 2010 Springer-Verlag.
Dey S.,Indian School of Mines |
Pandey U.K.,Atomic Minerals Directorate for Exploration and Research |
Rai A.K.,Atomic Minerals Directorate for Exploration and Research |
Chaki A.,Atomic Minerals Directorate for Exploration and Research
Journal of Asian Earth Sciences | Year: 2012
Geochemical and Nd isotope data on granitoids of the NW part of the late Archaean eastern Dharwar craton are presented to elucidate their petrogenesis and role in crust formation. The granitoids are divided into three suites viz. trondhjemite-granodiorite gneisses, biotite monzogranites and porphyritic biotite granodiorites. The gneisses are pre- to syn-kinematic (with respect to deformation in the adjacent Hungund-Kushtagi schist belt), which show variable SiO 2 and Al 2O 3, enriched LREE and depleted HREE with slightly negative to no Eu anomalies. They display unusual chemistry in having higher FeO(T), K 2O, Ba, Cr and Ni compared to the typical Archaean tonalite-trondhjemite-granodiorite (TTG). The biotite monzogranites are mostly syn- to late-kinematic and exhibit evolved calc-alkaline compositions with high SiO 2, K 2O, LILE and LREE, depleted to undepleted HREE and strongly negative to no Eu anomalies. The porphyritic granodiorites show syn- to late-kinematic calc-alkaline, sanukitoid-like character with a wide range of SiO 2, higher TiO 2, P 2O 5, Sr, Ba, Cr and Ni, and lower Rb. They, however, uniquely display higher K 2O, ΣREE and Th than typical sanukitoids. The trondhjemite-granodiorite gneisses are interpreted as product of melting of a subducted basaltic slab followed by slight contamination from the overlying metasomatized mantle wedge. Subsequent melting of the extremely metasomatized mantle wedge resulted in formation of the parental magma of the porphyritic granodiorites. Intrusion of the latter triggered melting of the TTG crust accreted earlier and generated the evolved monzogranites. The monzogranites occurring east of the Hungund-Kushtagi schist belt show higher εNd but lower T DM ages than those occurring to the west, indicating that terranes with different histories were juxtaposed by lateral accretion. © 2011 Elsevier Ltd.
Basu H.,Atomic Minerals Directorate for Exploration and Research |
Sastry R.S.,Osmania University |
Achar K.K.,Atomic Minerals Directorate for Exploration and Research |
Umamaheswar K.,Atomic Minerals Directorate for Exploration and Research |
Parihar P.S.,Atomic Minerals Directorate for Exploration and Research
Precambrian Research | Year: 2014
An analysis of facies was done to understand the depositional environment and the palaeoclimate of the sedimentary succession from the lower part of the Palaeoproterozoic (~2.0. Ga) Gulcheru Formation exposed along the southwestern margin of the Cuddapah Basin. Twelve distinct sedimentary facies were identified and grouped into three main facies associations - wadi fan, ephemeral fluvial and aeolian. Identification of the fluvial and the aeolian facies allowed a more elaborate interpretation of the depositional environment and its palaeoclimate. Facies characteristics indicated that the sediments in the beginning were deposited in a dominantly aeolian realm, under warm and semiarid climatic condition. Translatent strata, pin stripe lamination, zibars, high-index granule ripples, sand sheet deposits, grainflow cross-strata and grainfall laminae, asymptotically down-lapping cross-strata often with erosional lower bounding surface and massive sand-bodies with bimodal fabric, the unambiguous evidences of aeolian depositional regime led to this conclusion. However, the aeolian regime was often punctuated temporarily by fluvial input from ephemeral streams during sudden rainstorm. Depending upon the size, character and availability of sediments, relief difference and the sediment/water ratio cohesionless debris flow, hyperconcentrated flood flow and sheetflood deposits were formed near the basin margin, whereas, coarse-load braided channel deposits were laid further inside the basin. Ephemeral lakes/ponds were formed due to stagnation of floodwater in normally dry interdune lows. Overbank-interdune sediments were deposited in those ephemeral lakes/ponds. Amongst the aeolian facies, translatent strata and sand sheet dominate in the west, whereas, massive beds and dunes with well-developed slipfaces dominate in the eastern part. The spatial distribution of the aeolian bedforms suggests development of erg apron to the west and dune field (erg) to the east. The aeolian sediments identified in the Gulcheru Formation may be considered to be amongst the oldest Palaeoproterozoic aeolian sediments of the world. © 2014 Elsevier B.V.
Tripathy S.,Indian Institute of Technology Bhubaneswar |
Bhattacharyya P.,Indian Statistical Institute |
Mohapatra R.,Minnesota State University, Mankato |
Som A.,Atomic Minerals Directorate for Exploration and Research |
Chowdhury D.,Indian Institute of Technology Kharagpur
Ecological Engineering | Year: 2014
The ratios of microbial parameters/organic carbon indicated that inhibition of microbial growth. The study was carried out on an municipal solid waste dumping site, more than hundred year old, located on the outskirts of Kolkata metropolitan city in India to determine the concentrations of different forms of selected metals (Zn, Cu, Pb, Cr, and Ni), their effect on microbial ecophysiological parameters (microbial biomass, microbial metabolic quotient, microbial respiration quotient), fluorescein diacetate hydrolyzing activity and enzyme activities in solid waste amended soils. A sequential extraction technique was used to quantify water soluble, exchangeable, carbonate bound, Fe/Mn oxide bound, organic bound, and residual fractions of metals. Metal concentrations in the two most labile fractions (i.e. water soluble and exchangeable fractions) were generally low. The concentrations of different forms of metals, microbial ecophysiological parameters and enzyme activities were found to be significantly higher in solid waste amended soils compared to the normal background soil around the study area. Significant positive correlations were observed between the microbial parameters and organic carbon content of the waste amended soil. The contents of microbial biomass C, fluorescein diacetate and enzyme activities did not necessarily decrease with increasing heavy metal content, reflecting the importance of other environmental factors, e.g. differences in organic C content. The ratios of different microbial parameters with organic C were significantly negatively correlated with metal concentrations while inhibition increased with increased bioavailability of metals. Although the waste amended soils had significantly higher microbial biomass and activities than the background soil, due to higher organic matter content, the ratios of microbial parameters/organic carbon indicated that inhibition of microbial growth and activities had occurred due to metal stress. This indicates that the use of municipal solid wastes in agriculture would lead to destruction of soil quality in the long run. © 2014 Elsevier B.V..
Kukreti B.M.,Bhabha Atomic Research Center |
Kumar P.,AMD Inc |
Sharma G.K.,Atomic Minerals Directorate for Exploration and Research
Applied Radiation and Isotopes | Year: 2015
Exploratory drilling was undertaken in the Lostoin block, West Khasi Hills district of Meghalaya based on the geological extension to the major uranium deposit in the basin. Gamma ray logging of drilled boreholes shows considerable subsurface mineralization in the block. However, environmental and exploration related challenges such as climatic, logistic, limited core drilling and poor core recovery etc. in the block severely restricted the study of uranium exploration related index parameters for the block with a high degree confidence. The present study examines these exploration related challenges and develops an integrated approach using representative sampling of reconnoitory boreholes in the block. Experimental findings validate a similar geochemically coherent nature of radio elements (K, Ra and Th) in the Lostoin block uranium hosting environment with respect to the known block of Mahadek basin and uranium enrichment is confirmed by the lower U to Th correlation index (0.268) of hosting environment.A mineralized zone investigation in the block shows parent (refers to the actual parent uranium concentration at a location and not a secondary concentration such as the daughter elements which produce the signal from a total gamma ray measurement) favoring uranium mineralization. The confidence parameters generated under the present study have implications for the assessment of the inferred category of uranium ore in the block and setting up a road map for the systematic exploration of large uranium potential occurring over extended areas in the basin amid prevailing environmental and exploratory impediments. © 2015 Elsevier Ltd.
Maithani P.B.,Atomic Minerals Directorate for Exploration and Research |
Srinivasan S.,Atomic Minerals Directorate for Exploration and Research
Energy Procedia | Year: 2011
Felsic volcanics constitute a primary source of uranium for forming an economic deposit. All over the world, volcanic rocks have not received due attention they deserve in uranium exploration. The volcanogenic deposits have been grouped with "other deposits", as they constitute a meager <0.5% of world uranium resources. Exploration inputs in the western world have identified a number of uranium deposits associated with volcanic rocks. The uranium resources contributed by volcanic type deposits all over the world stand at 3, 62, 000 te U3O8 (IAEA 2008 Compilation). The significance of acid volcanic rocks as a potential uranium source lies in the readily leachable form of their uranium content. A detailed study carried out in Australia to understand the spatial and temporal relationsh ip between the uranium deposits and the unmineralized, uranium enriched rocks from across the continent clearly indicated the role of the acidic volcanics as a potential provenance. Among the acid volcanics, rhyolites form an ideal source followed by welde d tuffs, ignimbrites, etc. The alkali or topaz rhyolite is ideal for its enrichment in many lithophile elements including uranium, which are amenable to subsequent leaching by meteoric water. In India the uranium exploration activities in the early 50s till the 90s were mainly confined to the Singhbhum Shear Zones, the Himalayas, Meghalaya plateau, parts of Central India and the geological environs of the Dharwar Craton. The granitic rocks, especially the peraluminous biotite - granite was always considered as a potential source for uranium and the geological environs closer to these granites always remained the first order targets. A number of small to medium size uranium deposits have been identified in Singhbhum Shear Zone, parts of Cuddappah, Bhima Basins and in Meghalaya. Now since the significance of the volcanic rocks, especially the felsic volcanics as a potential source of uranium has been clearly understood, it is imperative to reorient our exploration strategy to tap the potential of these volcanic rocks. The Malani Magmatic Province (MMP) in the northwestern part is the largest suite of an-orogenic acid volcanics in India occupying an area of 50000 sqkm. The Proterozoic Basins of India are replete with volcanic activity, mainly acid volcanism. In the southern and Central India, Dharwar and parts of Central Indian Craton also witnessed significant acidic igneous activities. The Cuddapah and the Vindhyan Basins have also recorded extensive acidic volcanic activity in the Papaghni, Chitrvati, Nallamalai Groups and Semri and Kaimur Groups respectively. In view of this the Proterozoic Basins mentioned above and the geological environs adjacent to the MMP deserve a re -look to have a proper assessment of their uranium potential, using integrated exploration inputs. © 2011 Published by Elsevie Ltd.