sikta patnaik | Homi Bhabha National Institute (HBNI, BARC, MUMBAI) (original) (raw)

Papers by sikta patnaik

Research paper thumbnail of Organic Matter (OM) Associated Uranium Mineralisation in Kaimur Group of Vindhyan Supergroup near Maha-Rampura, Gwalior District, Madhya Pradesh, India

Journal of the Geological Society of India

Research paper thumbnail of Sulphur Isotopic Studies of Pyrite from Gogi Uranium Deposit, Bhima Basin, Karnataka

Journal of the Geological Society of India, 2021

Uranium deposit at Gogi area is located along the E-W Gundahalli-Gogi-Kurlegere (GK) fault, in th... more Uranium deposit at Gogi area is located along the E-W Gundahalli-Gogi-Kurlegere (GK) fault, in the brecciated impure limestone of Shahabad Formation of the Bhima Group of sediments and the basement granite in the central part of the Meso-Neoproterozoic Bhima basin. Uranium mineralisation is associated mainly with sulphide bearing minerals and secondary calcite. Ore microscopic studies indicate that among the sulphide minerals pyrite is predominant (about 98%) with subordinate amounts of chalcopyrite, chalcocite, marcasite, arsenopyrite and galena. Megascopically, three different varieties of pyrite viz., euhedral, lumpy and vein types are identified in the limestone and siltstone. Ore microscopic studies reveal that vein type pyrite and lumpy pyrite are fractured and crushed. Euhedral pyrite is idiomorphic and devoid of any fractures. The pyrite samples were analysed for δ34S sulphur isotopes. The δ34S values show a wide range from −30.51 to +20.77‰ (Canyon Diablo Troilite, CDT). δ34S values of pyrite can be classified into three groups depending on the values. High values of +17.73 to +20.77 ‰ (CDT) of euhedral pyrite (Py-I) indicate sedimentary pyrite formed due to bacterial reduction of sea water sulphate in relatively closed system, while pyrite (Py-II) having negative values of δ34S imply bacterial reduction of sea water sulphate in open system. The third group (Py-III) of pyrite have δ34S values of −0.51‰ (CDT) and 7.38‰ (CDT), indicating their magmatic/hydrothermal origin. Sulphides in the deformed sediments acted as reducing agent for uranium precipitation.

Research paper thumbnail of A Note on the Occurrence of Hydrothermal Anhydrite (CaSO4) in Kanchankayi area, Bhima Basin, Yadgir District, Karnataka

Proceedings of the Indian National Science Academy, 2020

Presence of hydrothermal anhydrite (CaSO 4) is identified from the brecciated limestone of Shahab... more Presence of hydrothermal anhydrite (CaSO 4) is identified from the brecciated limestone of Shahabad Formation of the Proterozoic Bhima basin, Northern Karnataka. This is specifically observed in the Kanchankayi area of Gogi-Kurlegere-Gundanhalli fault, Bhima basin. Microscopically the anhydrite is characteristised by high order interference colour and straight extinction. X-ray diffraction studies further confirmed the presence of anhydrite with characteristic set of dspacing of 4.6397Å (Intensity-60.71), 3.4584 Å (56.76) and 2.7730 Å (23.22). Subherdal to anhedral grains of anhydrite occur within the veins of sparry calcite cutting across the primary micritic calcite in brecciated limestone. It is associated with calcite, barite pyrite and carbonaceous matter. Anhydrite is present in different habits viz. tabular/euhedral,stumpy and acicular. Occurrence of anhydrite grains is localised and is restricted to the epigenetic secondary calcite. This suggests it is of hydrothermal origin.

Research paper thumbnail of Petrographic Characteristics of Carbonaceous Matter in Brecciated Limestone at Kanchankayi Area, Yadgir District, Karnataka: Genetic Implications for Uranium Mineralisation

Journal of Applied Geochemistry, 2016

Uranium mineralization at Gogi area, along the Kurlegere-Gogi-Gundanhalli fault in Bhima basin is... more Uranium mineralization at Gogi area, along the Kurlegere-Gogi-Gundanhalli fault in Bhima basin is well established. Its northeastern extension at Kanchankayi area has indicated the presence of pitchblende and coffinite as the major radioactive ore minerals, which are associated with sulphide minerals, secondary calcite and carbonaceous matter. Petromineralogical studies have shown that carbonaceous matter is present in various textural forms like meshwork, stringers, as colloidal matter, globules and veins. It shows various colours, opacity and a range of reflectance. It is mainly present in association with sulphides and calcite. Some of the carbonaceous matters are radioactive, while others are devoid of any radioactive phases.

Research paper thumbnail of Petro-mineralogical and geochemical characteristics of Shahaba Limestone from Gogi-Kanchankayi sector, Bhima Basin, Karnataka with reference to Uranium mineralisation

Journal of The Indian Association of Sedimentologists, 2021

The Shahabad Limestone Formation of Bhima Basin from Gogi-Kanchankayi area occurs in heterogeneou... more The Shahabad Limestone Formation of Bhima Basin from Gogi-Kanchankayi area occurs in heterogeneous forms like massive/blocky limestone, argillaceous/ siliceous limestone and laminated/ flaggy limestone. These limestones are primarily composed of micrite, which often alters into sparry calcite on diagenesis with associated impurities of quartz, feldspar, barite, chlorite, glauconite, sulphides and carbonaceous matter. Geochemically, these limestones comprises of variable CaO with low MgO and P2O5 content. Trace elements concentration shows elevated Ba, Rb and depleted Sr. The current study classified these limestones as non-dolomitic and non-phosphatic types deposited in shallow marine carbonate platform setting with low energy conditions. Post-sedimentation, basin tectonics has resulted in reactivation of the basin margin fault causing intense fracturing of limestone. Subsequent hydrothermal movement along those fractures has resulted in re-mobilisation and re-precipitation of sulph...

Research paper thumbnail of Geochemical behaviour of LREE, Y and Zr in uranium mineralized and non-mineralized granite from Darshanapur area, in the Gogi-Kurlagere fault zone, Bhima basin, Yadgiri district, Karnataka

Journal of the Geological Society of India, 2016

Granite core samples (n=14) from the Gogi-Kurlagere fault zone in the central part of the Bhima b... more Granite core samples (n=14) from the Gogi-Kurlagere fault zone in the central part of the Bhima basin were studied in terms of LREE, Y and Zr mobility during uranium mineralization. LREE, Zr and Y along with LILE (Ba, Rb) and P show behavioral differences in the mineralised and the non-mineralised samples. Average ΣLREE in mineralised granite (240 ppm) is higher than in non-mineralised samples (157 ppm). The average Zr and Y in the mineralised granite are 193 ppm and 17 ppm, while the corresponding abundances of these elements in non-mineralised portion are 148 ppm and 11 ppm respectively. Besides enrichment of U, Th, Ba, Pb and Rb and depletion of Sr are observed in mineralized granite in comparison to non-mineralized granite. Hydrothermal alteration has led to the mobility of these elements, which again dependent on the overall geochemical behavior of the migrating fluid. REE and Y in association with uranyl [(UO2)2+] ion were transported as carbonate complexes like [UO2(CO3)3]4- and [REE (CO3)3]3- and were later incorporated into favourable structural loci by precipitating minerals like pitchblende and coffinite.

Research paper thumbnail of Organic Matter (OM) Associated Uranium Mineralisation in Kaimur Group of Vindhyan Supergroup near Maha-Rampura, Gwalior District, Madhya Pradesh, India

Journal of the Geological Society of India

Research paper thumbnail of Sulphur Isotopic Studies of Pyrite from Gogi Uranium Deposit, Bhima Basin, Karnataka

Journal of the Geological Society of India, 2021

Uranium deposit at Gogi area is located along the E-W Gundahalli-Gogi-Kurlegere (GK) fault, in th... more Uranium deposit at Gogi area is located along the E-W Gundahalli-Gogi-Kurlegere (GK) fault, in the brecciated impure limestone of Shahabad Formation of the Bhima Group of sediments and the basement granite in the central part of the Meso-Neoproterozoic Bhima basin. Uranium mineralisation is associated mainly with sulphide bearing minerals and secondary calcite. Ore microscopic studies indicate that among the sulphide minerals pyrite is predominant (about 98%) with subordinate amounts of chalcopyrite, chalcocite, marcasite, arsenopyrite and galena. Megascopically, three different varieties of pyrite viz., euhedral, lumpy and vein types are identified in the limestone and siltstone. Ore microscopic studies reveal that vein type pyrite and lumpy pyrite are fractured and crushed. Euhedral pyrite is idiomorphic and devoid of any fractures. The pyrite samples were analysed for δ34S sulphur isotopes. The δ34S values show a wide range from −30.51 to +20.77‰ (Canyon Diablo Troilite, CDT). δ34S values of pyrite can be classified into three groups depending on the values. High values of +17.73 to +20.77 ‰ (CDT) of euhedral pyrite (Py-I) indicate sedimentary pyrite formed due to bacterial reduction of sea water sulphate in relatively closed system, while pyrite (Py-II) having negative values of δ34S imply bacterial reduction of sea water sulphate in open system. The third group (Py-III) of pyrite have δ34S values of −0.51‰ (CDT) and 7.38‰ (CDT), indicating their magmatic/hydrothermal origin. Sulphides in the deformed sediments acted as reducing agent for uranium precipitation.

Research paper thumbnail of A Note on the Occurrence of Hydrothermal Anhydrite (CaSO4) in Kanchankayi area, Bhima Basin, Yadgir District, Karnataka

Proceedings of the Indian National Science Academy, 2020

Presence of hydrothermal anhydrite (CaSO 4) is identified from the brecciated limestone of Shahab... more Presence of hydrothermal anhydrite (CaSO 4) is identified from the brecciated limestone of Shahabad Formation of the Proterozoic Bhima basin, Northern Karnataka. This is specifically observed in the Kanchankayi area of Gogi-Kurlegere-Gundanhalli fault, Bhima basin. Microscopically the anhydrite is characteristised by high order interference colour and straight extinction. X-ray diffraction studies further confirmed the presence of anhydrite with characteristic set of dspacing of 4.6397Å (Intensity-60.71), 3.4584 Å (56.76) and 2.7730 Å (23.22). Subherdal to anhedral grains of anhydrite occur within the veins of sparry calcite cutting across the primary micritic calcite in brecciated limestone. It is associated with calcite, barite pyrite and carbonaceous matter. Anhydrite is present in different habits viz. tabular/euhedral,stumpy and acicular. Occurrence of anhydrite grains is localised and is restricted to the epigenetic secondary calcite. This suggests it is of hydrothermal origin.

Research paper thumbnail of Petrographic Characteristics of Carbonaceous Matter in Brecciated Limestone at Kanchankayi Area, Yadgir District, Karnataka: Genetic Implications for Uranium Mineralisation

Journal of Applied Geochemistry, 2016

Uranium mineralization at Gogi area, along the Kurlegere-Gogi-Gundanhalli fault in Bhima basin is... more Uranium mineralization at Gogi area, along the Kurlegere-Gogi-Gundanhalli fault in Bhima basin is well established. Its northeastern extension at Kanchankayi area has indicated the presence of pitchblende and coffinite as the major radioactive ore minerals, which are associated with sulphide minerals, secondary calcite and carbonaceous matter. Petromineralogical studies have shown that carbonaceous matter is present in various textural forms like meshwork, stringers, as colloidal matter, globules and veins. It shows various colours, opacity and a range of reflectance. It is mainly present in association with sulphides and calcite. Some of the carbonaceous matters are radioactive, while others are devoid of any radioactive phases.

Research paper thumbnail of Petro-mineralogical and geochemical characteristics of Shahaba Limestone from Gogi-Kanchankayi sector, Bhima Basin, Karnataka with reference to Uranium mineralisation

Journal of The Indian Association of Sedimentologists, 2021

The Shahabad Limestone Formation of Bhima Basin from Gogi-Kanchankayi area occurs in heterogeneou... more The Shahabad Limestone Formation of Bhima Basin from Gogi-Kanchankayi area occurs in heterogeneous forms like massive/blocky limestone, argillaceous/ siliceous limestone and laminated/ flaggy limestone. These limestones are primarily composed of micrite, which often alters into sparry calcite on diagenesis with associated impurities of quartz, feldspar, barite, chlorite, glauconite, sulphides and carbonaceous matter. Geochemically, these limestones comprises of variable CaO with low MgO and P2O5 content. Trace elements concentration shows elevated Ba, Rb and depleted Sr. The current study classified these limestones as non-dolomitic and non-phosphatic types deposited in shallow marine carbonate platform setting with low energy conditions. Post-sedimentation, basin tectonics has resulted in reactivation of the basin margin fault causing intense fracturing of limestone. Subsequent hydrothermal movement along those fractures has resulted in re-mobilisation and re-precipitation of sulph...

Research paper thumbnail of Geochemical behaviour of LREE, Y and Zr in uranium mineralized and non-mineralized granite from Darshanapur area, in the Gogi-Kurlagere fault zone, Bhima basin, Yadgiri district, Karnataka

Journal of the Geological Society of India, 2016

Granite core samples (n=14) from the Gogi-Kurlagere fault zone in the central part of the Bhima b... more Granite core samples (n=14) from the Gogi-Kurlagere fault zone in the central part of the Bhima basin were studied in terms of LREE, Y and Zr mobility during uranium mineralization. LREE, Zr and Y along with LILE (Ba, Rb) and P show behavioral differences in the mineralised and the non-mineralised samples. Average ΣLREE in mineralised granite (240 ppm) is higher than in non-mineralised samples (157 ppm). The average Zr and Y in the mineralised granite are 193 ppm and 17 ppm, while the corresponding abundances of these elements in non-mineralised portion are 148 ppm and 11 ppm respectively. Besides enrichment of U, Th, Ba, Pb and Rb and depletion of Sr are observed in mineralized granite in comparison to non-mineralized granite. Hydrothermal alteration has led to the mobility of these elements, which again dependent on the overall geochemical behavior of the migrating fluid. REE and Y in association with uranyl [(UO2)2+] ion were transported as carbonate complexes like [UO2(CO3)3]4- and [REE (CO3)3]3- and were later incorporated into favourable structural loci by precipitating minerals like pitchblende and coffinite.