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| Tourmaline from the Archean G.R.Halli gold deposit,Chitradurga greenstone belt,Dharwar craton （India）： Implications for the gold metallogeny | |
| 作者姓名： | Susmita Gupta ;M. Jayananda ;Fareeduddin |
| 作者单位： | [1]Geological Survey of India (GSI), NER, Cuwahati, Assam 781 005, India; [2]Department of Geology, Centre of Advanced Studies, University of Delhi, Delhi 110 007, India; [3]Geochronology and Isotope Geology Division, Central Headquarter, GSI, Kolkata 700 016, India |
| 摘 要： | Tourmaline occurs as a minor but important mineral in the alteration zc,ne of the Archean orogenic gold deposit of Guddadarangavanahalli （G.R.Halli） in the Chitradurga greenst~ne belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli golcl deposit as （a） clusters of very fine grained aggregates which form a minor constituent in the natrix of the altered metabasalt （AMB tourmaline） and （b） in quartz-carbonate veins （vein tourmaline）. ~＇he vein tourmaline, based upon the association of specific carbonate minerals, is further grouped as （i） albite-tourmaline-ankerite-quartz veins （vein-1 tourmaline） and （ii） albite-tourmaline-calcite-quartz veins （vein-2 tourmaline）. Both the AMB tourmaline and the vein tourmalines （vein-I and vein-2） belong to the alkali group and are clas- sified under schorl-dravite series. Tourmalines occurring in the veins are zoned while the AMB tour- malines are unzoned. Mineral chemistry and discrimination diagrams 1eveal that cores and rims of the vein tourmalines are distinctly different. Core composition of the ve：n tourmalines is similar to the composition of the AMB tourmaline. The formation of the AMB tourmaline and cores of the vein tour- malines are proposed to be related to the regional D1 deformational event associated with the emplacement of the adjoining ca. 2.61 Ga Chitradurga granite whilst rims of the vein tourmalines vis-a- vis gold mineralization is spatially linked to the juvenile magmatic accretion （2.56-2.50 Ga） east of the studied area in the western part of the eastern Dharwar craton. |
| 关 键 词： | 电气石 克拉通 金矿化 印度 太古代 绿岩带 金成矿 碳酸盐矿物 |
| 收稿时间： | 20 September 2012 |
http://www.sciencedirect.com/science/article/pii/S1674987113001618 |
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| Susmita Gupta,;M. Jayananda,;Fareeduddin.http://www.sciencedirect.com/science/article/pii/S1674987113001618[J].Geoscience Frontiers,2014,5(6):877-892. | |
| Authors: | Susmita Gupta M Jayananda Fareeduddin |
| Institution: | 1. Geological Survey of India GSI, NER, Guwahati, Assam 781 005, India 2. Department of Geology, Centre of Advanced Studies, University of Delhi, Delhi 110 007, India 3. Geochronology and Isotope Geology Division, Central Headquarter, GSI, Kolkata 700 016, India |
| Abstract: | Tourmaline occurs as a minor but important mineral in the alteration zone of the Archean orogenic gold deposit of Guddadarangavanahalli (G.R.Halli) in the Chitradurga greenstone belt of the western Dharwar craton, southern India. It occurs in the distal alteration halo of the G.R.Halli gold deposit as (a) clusters of very fine grained aggregates which form a minor constituent in the matrix of the altered metabasalt (AMB tourmaline) and (b) in quartz-carbonate veins (vein tourmaline). The vein tourmaline, based upon the association of specific carbonate minerals, is further grouped as (i) albite-tourmaline-ankerite-quartz veins (vein-1 tourmaline) and (ii) albite-tourmaline-calcite-quartz veins (vein-2 tourmaline). Both the AMB tourmaline and the vein tourmalines (vein-1 and vein-2) belong to the alkali group and are classified under schorl-dravite series. Tourmalines occurring in the veins are zoned while the AMB tourmalines are unzoned. Mineral chemistry and discrimination diagrams reveal that cores and rims of the vein tourmalines are distinctly different. Core composition of the vein tourmalines is similar to the composition of the AMB tourmaline. The formation of the AMB tourmaline and cores of the vein tourmalines are proposed to be related to the regional D1 deformational event associated with the emplacement of the adjoining ca. 2.61 Ga Chitradurga granite whilst rims of the vein tourmalines vis-à-vis gold mineralization is spatially linked to the juvenile magmatic accretion (2.56–2.50 Ga) east of the studied area in the western part of the eastern Dharwar craton. |
| Keywords: | Tourmaline G R Hal i Orogenic gold deposit Dharwar craton Archean |
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