Browsing by Author "Prabhakar Sangurmath"

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Abundance of Carbonic Fluid Inclusions in Hira-Buddini Gold Deposit, Hutti-Maski Greenstone Belt, India: Inferences from Petrography and Volume Ratio Estimation of Fluid Components
(China University of Geosciences, 2020) Rajagopal Krishnamurthi; Ajit Kumar Sahoo; Rajesh Sharma; Prabhakar Sangurmath
Low saline aqueous carbonic fluids are considered to be the ore forming solutions for orogenic lode gold deposits. Phase separation/fluid immiscibility of the ore fluid is quite common and is one of the major reasons for deposition of gold in these deposits. Abundant carbonic fluid inclusions have been observed in quartz grains of Hira-Buddnini Gold Deposit. Theoretical estimation indicates that more volume of H2O compared to CO2 is likely to be trapped in inclusions at different P-T conditions. Preferential loss of H2O from fluid inclusions during ductile deformation of quartz grains have been attributed as the suitable reason for abundance of carbonic fluid inclusions. © 2020, China University of Geosciences (Wuhan) and Springer-Verlag GmbH Germany, Part of Springer Nature.
Gold Mineralization at Paramanahalli Prospect, Chitradurga Greenstone Belt, Western Dharwar Craton, Karnataka, India
(Geological Society of India, 2025) Manju Sati; Rajagopal Krishnamurthi; Sakthi Saravanan Saravanan Chinnasamy; Ajit Kumar Sahoo; Prabhakar Sangurmath
Paramanahalli gold prospect is hosted by deformed metamorphosed volcano-sedimentary rocks of the Chitradurga Group. Mineralization is confined to altered host rocks and quartz veins, and structurally controlled by NNW-SSE trending ductile to brittle-ductile shear zones. Surface indication of mineralization is found in the form of sulfide-rich quartz-ankerite veins with pyrite disseminated in host rocks. Detailed petrographic studies indicate a mineral assemblage of chlorite-1 ± biotite ± albite ± quartz in metabasalt formed by low-grade metamorphism. Microstructures such as brecciation, microfractures, micro folds, and strain fringes indicate that the metamorphosed volcano-metasedimentary rocks (metabasalt, phyllite, greywacke) experienced brittle-ductile deformation. Carbonatization and sulfidation are common hydrothermal alterations in the areas of oxide facies of the Banded Iron Formation (BIF), where gold is enriched. Altered metabasalt and BIF contain a significant amount of sulfides with native gold. The above studies indicate that mineralization at Paramanahalli was associated with deformation and alteration processes. Hence, an attempt has been made to understand the genetic aspects of gold mineralization at the Paramanahalli gold prospect based on petrography and mineralogy of altered host rocks. © 2025 Geological Society of India, Bengaluru, India.
Nature of ore forming fluids, wallrock alteration and P-T conditions of gold mineralization at Hira-Buddini, Hutti-Maski Greenstone Belt, Dharwar Craton, India
(Elsevier B.V., 2018) Ajit Kumar Sahoo; Rajagopal Krishnamurthi; Prabhakar Sangurmath
Gold mineralization at Hira-Buddini deposit in Hutti-Maski Greenstone Belt of Dharwar Craton, India is associated with quartz veins and hydrothermal alteration formed during a brittle-ductile deformation episode. The vein minerals (quartz and plagioclase) exhibit microstructures of dynamic recrystallization/intracrystalline deformation. Estimated temperature and pressure condition during mineralization is around 500 °C and 2.05–4.36 kbar, respectively. Carbonic inclusions are the most abundant type of fluid inclusions found in quartz grains of mineralized veins. Such abundance of carbonic inclusions must be due to preferential loss of water from original fluid inclusions during intracrystalline deformation of quartz. Rock-fluid interaction led to enrichment of SiO2 (in the form of quartz veins), K, Pb, S and LOI in the auriferous lode. It is inferred that the hydrothermal fluids involved in gold mineralization were of both metamorphic and magmatic origin. Deposition of gold has been attributed to phase separation as well as wall rock sulfidation. © 2018 Elsevier B.V.