Gold Mineralisation in Chigargunta Area of the Kolar Schist Belt, South India- A Part of the Archean Greenstone Belt
Volume 4, Issue 4-1, July 2015, Pages: 40-45
Received: Apr. 23, 2015;
Accepted: May 5, 2015;
Published: Jul. 29, 2015
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Debasish Roy, Retired Director, G.S.I, Kolkata, INDIA
Gold mineralisation is reported for the first time in ‘Champion gneiss’ (quartzo-feldspathic schist) a felsic unit,in the eastern sector of the Chigargunta area (Lat: 120 430300N, Long:780 150 000E) of the Kolar schist belt, South India, during 1979-80. Quartzo-feldspathic gneiss and hornblende schist are the predominant rock types of the area. These rocks are characterised by a strong pervasive foliation trending N50E –S50W to N200E - S200W with easterly dips of 70-85. In the northern part of the area the rocks are folded with the foliation which is axial planar. Lower to middle amphibolite facies metamorphism is widespread in the area. Gold mineralisation is localised along shear zones which are ductile to brittle in nature. These zones are parallel to subparallel to the trend of foliation in the host rock and are characterized by strong mylonitic fabric, profuse quartz venation and hydrothermal alteration. Pyrite and pyrrhotite are the dominant sulphides. Gold occurs in native form. This felsic hosted gold mineralisation termed as E-2 lode (for exploration purpose) is estimated to contain a reserve of 3.13 million tonnes averaging 4.7 g/t gold. Besides, this lode there are several loads ( E-1,E-3, etc) occur within mafic units as well as in felsic unit adjacent to E-2 lode with different reserves, within the schist belt. Epigenetic gold mineralisation shows a close temporal and spatial relationship to late Archean (2700-2500 m.y) crustal accretion, stabilisation and granulite formation in the South Indian Shield. The present work delineate, the nature of mineralization in felsic unitwithin the schist belt which was not considered as source rock of gold mineralization during the period and left untouched until the present work
Gold Mineralisation in Chigargunta Area of the Kolar Schist Belt, South India- A Part of the Archean Greenstone Belt, Earth Sciences. Special Issue: Archean Metallogeny and Crustal Evolution.
Vol. 4, No. 4-1,
2015, pp. 40-45.
Cameron,E.M 1988. Archean Gold: Relation to Granulite formation and Redox Zoning in the crust. 16(2), 109-112
Narayanaswami, S., 1963. The gold fields of India. Geol.Soc.Ind.Mem,. 1, 39-48
Ridley,et.al., 1990. Wall rock alteration in amphibolite facies gold deposit. University of Western Australia, Publication 20, 79-86
Narayanaswami, S., Ziauddin,M and Ramachandra, A.V., 1960 . Structural Control and Localisation of Gold-Bearing lode, Kolar Gold Fields, India. Econ.Geol, 55, 1429-1459
Naqvi, S.M., 2005: Geology and Evolution of the Indian plate (From Hadean to Holocene 4Ga to 4 Ka) Capital Pub. Co. (New Delhi), 2005, 10-56
Swaminath, J. and Ramkrishna,M., 1981. Early Precambrian Supracrustals of Southern Karnataka.Mem.Geol.Surv.Ind. 112, 221-245
Hanson,G.N., Krogstad,E.F,. and Rajamani,V., 1988. Tectonic Setting of the Kolar Schist Belt,Karnataka, India (Abstract) J.Geol. Soc. Ind, 31,40-42.
Shashidharan, K. Roy. Debasish, Mukherjee, M.M.and Natarajan, W.K., 1987. A Report On The Investigation for Gold in ‘Champion Gneiss’ Chigurgunta, (Blocks III,II,I) Eastern Sector, Chittoor District, Andhra Pradesh (F.S.P. 1983-84). Unpublished Report. Southern Region, Geological Survey of India
Mukherjee, M.M., Evolutionary aspect of Gold Mineralisation in Southern part of Kolar Schist Belt, Indian Minerals, 43,( 3&4), 347-360.
Charan,S.N., Naqvi, S,M and Ramesh,S.L. 1988, Geology and Geochemistry of Spinifex-Textured Peridotite Komatiite from Mayasandra Schist Belt, Karnataka. J.Geol. Soc. Ind, 32,343-350
Stanton,R.L.,1976 Petrochemical studies of the ore environment at Broken Hill, New South Wales, Tr. Inst. Min. Metal, 85(B), 221-233
Siva Siddaiah, N. and Rajamani, V,. 1989: The Geologic setting, mineralogy,Geochemistry and genesis of gold deposits of the Archean Kolar Schist Belt, India. Econ. Geol., 84, 2155-2172.
Seibold,E and Berger, W.H 1982. The sea floor. Springer-Verlag, Berlin,244
Condie,K.C and Allen,P., 1984. Origin of Archean Charnockites from Southern India. In ‘Archean Geochemistry’- The Origin and Evolution of the Archean Continental crust, Springer-Verlag, 161-181
Gopalakrishnan,D.,Hansen,E.C, Janardhan,A.S and Newton, R.C., 1986 The southern high grade margin of Dharwar Craton J Geol., 94, 247-260.