Auriferous lode of Hira-Buddini gold mine, Hutti-Maski schist belt, Dharwar craton: Mineralogy, alteration, types and mechanism of vein emplacement

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• 作者：Ajit Kumar Sahoo ; R. Krishnamurthi…
• 关键词：Aurifeorous lode ; Gold mineralization ; Hira ; Buddini ; Hutti ; Maski Schist Belt ; Karnataka
• 刊名：Journal of the Geological Society of India
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：88
• 期：6
• 页码：675-684
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geology; Hydrogeology;
• 出版者：Geological Society of India
• ISSN：0974-6889
• 卷排序：88

文摘

The auriferous lode in the Hira-Buddini deposit is confined to the sheared contact of amphibolite and felsic metavolcanic rock. Gold mineralization in the deposit is associated with sub-horizontal, sub–vertical, irregular and with few conjugate veins. These veins were emplaced during deformation in a ductile-brittle regime as inferred from the megascopic features and microstructures of the vein minerals. Fluid pressure was higher than the sum of the minimum principal stress and lithostatic load as well as the tensile strength of the shear zone. Crack-seal process appears to be the mechanism of vein formation. The microstructures of the vein minerals indicate a temperature of ~500ºC during the vein emplacement. In the auriferous lode, amphibolite and felsic metavolcanic rock have been subjected to intense alteration by the ore fluid with development of biotite-chlorite-tourmaline-calcite and muscovite (sericite)-chlorite-calcite-feldspar-biotite assemblages, respectively. Both the altered rocks contain significant amount of pyrite and chalcopyrite with native grains of gold and silver. Post-dating the fluid activity associated with gold mineralization, there is another stage of fluid activity manifested by the calcite veins and micro-veinlets.