The Jayachamarajapura schist belt in western Dharwar craton, southern India, is predominantly an ultramafics dominant terrain. These rocks have been extensively metamorphosed and altered to serpentinite. The komatiite...The Jayachamarajapura schist belt in western Dharwar craton, southern India, is predominantly an ultramafics dominant terrain. These rocks have been extensively metamorphosed and altered to serpentinite. The komatiite nature of ultramafics is conspicuous. In most of the areas of the belt these ultramafics are massive in nature. However, some of the ultramafic units show layered nature. But, their outcrops are encompassed within the massive komatiitic bodies. These komatiitic ultramafics are predominantly Mg-rich in nature. The layered rocks are also Mg-rich, and their field setting and geochemistry suggest their intermittent occurrence as sills, during the differentiation of peridotitic magma. The layered rocks, which have been intensely serpentinisation show homogenous nature. They are almost wholly made of serpentine with occasional relics of pyroxene. Secondary carbonate mineral is often noticed. Their higher MgO content indicates Mg-rich ultramafic magmatism during Archaean orogeny.展开更多
Stream sediment sampling is a significant tool in geochemical exploration. The stream sediment composition reflects the bedrock geology, overburden cover, and metalliferous mineralization. This research article focuse...Stream sediment sampling is a significant tool in geochemical exploration. The stream sediment composition reflects the bedrock geology, overburden cover, and metalliferous mineralization. This research article focuses on assessing selected trace element concentrations in stream sediments and interpreting their inter-element relationships using multivariate statistical methods. Tagadur Ranganathaswamy Gudda and its surroundings in the Nuggihalli schist belt of southern India have been investigated in the present work. The geology of the study area is complex, with a diverse range of litho units and evidence of strong structural deformation. The area is known for its mineralization potential for chromite, vanadiferous titanomagnetite, and sulfides. The topography of the region is characterized by an undulating terrain with a radial drainage pattern. Most part of the schist belt is soil covered except the Tagadur Ranganathaswamy Gudda area. For this study, a discrete stream sediment sampling method was adopted to collect the samples. Stream sediment samples were collected using a discrete sampling method and analyzed for trace elements using an ICP-AES spectrophotometer: Fe, Cr, Ti, V, Cu, Ni, Zn, Pb, Mn, Cd, and As have been analyzed. The analytical data were statistically treated using the SPSS software, including descriptive statistics, normalization of data using natural log transformation, and factor analysis with varimax rotation. The transformed data showed a log-normal distribution, indicating the presence of geochemical anomalies. The results of the study provide valuable insights into the geochemical processes and mineralization potential of the study area. The statistical analysis helps in understanding the inter-element relationships and identifying element groups and their implications on bedrock potential mineralization. Additionally, spatial analysis using inverse distance weighting interpolation provides information about the distribution of geochemical parameters across the study area. Overall, this research contributes to the understanding of stream sediment geochemistry and its application in mineral exploration. The findings have implications for future exploration efforts and can aid in the identification of potential ore deposits in the Nuggihalli schist belt and similar geological settings.展开更多
JC Pura schist belt has gained scope recently with reports of nickel, magnetite, PGEs, and traces of gold. The layered sill in the schist belt is a linear patch of ultramafic sequences (peridotite and pyroxenite) with...JC Pura schist belt has gained scope recently with reports of nickel, magnetite, PGEs, and traces of gold. The layered sill in the schist belt is a linear patch of ultramafic sequences (peridotite and pyroxenite) with metamorphogenic magnetite mineralization. The metamorphogenic magnetite appears as interbands in layered sequences and as veins in serpentinite. The present study focuses on understanding the characteristics of metamorphogenic magnetite by petrographic and EPMA analysis. The study found that the precursor chromite grains are transformed into Cr-magnetite and magnetite in the spinel transformation system due to metamorphism and hydrothermal alteration. The Cr, Mg, Al, and Ni are depleted during transformation, and Fe is enriched. The Cr-magnetite appears homogenous in the vein due to serpentinization, indicating prograde greenschist to amphibolite facies metamorphism, and the area has suffered an episodic metamorphic process. The results of Cr-magnetite cation proportions of Cr fall within ishkulite variety data range of 0.10 - 0.50 apfu (atoms per formula unit). Cr-magnetite variety Ishkulite represents an additional miscibility gap in the Cr-Fe3+ transformation series other than ferrite chromite and chrome magnetite. The transformation process primarily involves the oxidation of chromium and the reduction of iron. The oxidation of chromite by highly oxidizing fluids with increasing pressure and temperature alters to Cr-magnetite, where chromium in the +3 state oxidizes to the +6 state, forming soluble chromate ions and diffusing with Fe3+. Then, it transforms into magnetite due to reducing conditions. Cr-magnetite vein indicates the potential for chromite deposits in the area, and hydrothermal altered magnetites could be a source for hosting valuable precious metals like gold and PGEs. Further investigations are needed to assess the mineralization potential and its extent.展开更多
文摘The Jayachamarajapura schist belt in western Dharwar craton, southern India, is predominantly an ultramafics dominant terrain. These rocks have been extensively metamorphosed and altered to serpentinite. The komatiite nature of ultramafics is conspicuous. In most of the areas of the belt these ultramafics are massive in nature. However, some of the ultramafic units show layered nature. But, their outcrops are encompassed within the massive komatiitic bodies. These komatiitic ultramafics are predominantly Mg-rich in nature. The layered rocks are also Mg-rich, and their field setting and geochemistry suggest their intermittent occurrence as sills, during the differentiation of peridotitic magma. The layered rocks, which have been intensely serpentinisation show homogenous nature. They are almost wholly made of serpentine with occasional relics of pyroxene. Secondary carbonate mineral is often noticed. Their higher MgO content indicates Mg-rich ultramafic magmatism during Archaean orogeny.
文摘Stream sediment sampling is a significant tool in geochemical exploration. The stream sediment composition reflects the bedrock geology, overburden cover, and metalliferous mineralization. This research article focuses on assessing selected trace element concentrations in stream sediments and interpreting their inter-element relationships using multivariate statistical methods. Tagadur Ranganathaswamy Gudda and its surroundings in the Nuggihalli schist belt of southern India have been investigated in the present work. The geology of the study area is complex, with a diverse range of litho units and evidence of strong structural deformation. The area is known for its mineralization potential for chromite, vanadiferous titanomagnetite, and sulfides. The topography of the region is characterized by an undulating terrain with a radial drainage pattern. Most part of the schist belt is soil covered except the Tagadur Ranganathaswamy Gudda area. For this study, a discrete stream sediment sampling method was adopted to collect the samples. Stream sediment samples were collected using a discrete sampling method and analyzed for trace elements using an ICP-AES spectrophotometer: Fe, Cr, Ti, V, Cu, Ni, Zn, Pb, Mn, Cd, and As have been analyzed. The analytical data were statistically treated using the SPSS software, including descriptive statistics, normalization of data using natural log transformation, and factor analysis with varimax rotation. The transformed data showed a log-normal distribution, indicating the presence of geochemical anomalies. The results of the study provide valuable insights into the geochemical processes and mineralization potential of the study area. The statistical analysis helps in understanding the inter-element relationships and identifying element groups and their implications on bedrock potential mineralization. Additionally, spatial analysis using inverse distance weighting interpolation provides information about the distribution of geochemical parameters across the study area. Overall, this research contributes to the understanding of stream sediment geochemistry and its application in mineral exploration. The findings have implications for future exploration efforts and can aid in the identification of potential ore deposits in the Nuggihalli schist belt and similar geological settings.
文摘JC Pura schist belt has gained scope recently with reports of nickel, magnetite, PGEs, and traces of gold. The layered sill in the schist belt is a linear patch of ultramafic sequences (peridotite and pyroxenite) with metamorphogenic magnetite mineralization. The metamorphogenic magnetite appears as interbands in layered sequences and as veins in serpentinite. The present study focuses on understanding the characteristics of metamorphogenic magnetite by petrographic and EPMA analysis. The study found that the precursor chromite grains are transformed into Cr-magnetite and magnetite in the spinel transformation system due to metamorphism and hydrothermal alteration. The Cr, Mg, Al, and Ni are depleted during transformation, and Fe is enriched. The Cr-magnetite appears homogenous in the vein due to serpentinization, indicating prograde greenschist to amphibolite facies metamorphism, and the area has suffered an episodic metamorphic process. The results of Cr-magnetite cation proportions of Cr fall within ishkulite variety data range of 0.10 - 0.50 apfu (atoms per formula unit). Cr-magnetite variety Ishkulite represents an additional miscibility gap in the Cr-Fe3+ transformation series other than ferrite chromite and chrome magnetite. The transformation process primarily involves the oxidation of chromium and the reduction of iron. The oxidation of chromite by highly oxidizing fluids with increasing pressure and temperature alters to Cr-magnetite, where chromium in the +3 state oxidizes to the +6 state, forming soluble chromate ions and diffusing with Fe3+. Then, it transforms into magnetite due to reducing conditions. Cr-magnetite vein indicates the potential for chromite deposits in the area, and hydrothermal altered magnetites could be a source for hosting valuable precious metals like gold and PGEs. Further investigations are needed to assess the mineralization potential and its extent.
