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Sugavanam, E. B.
- Carbonatite around Ajjipuram, Kollegal Taluk, Karnataka
Authors
1 No.53, 9th 'E' Cross, S.B.I. Colony, J.P. Nagar I Phase. Bangalore -560078, IN
2 No. 693, Yelahanka, Bangalore- 560064, IN
3 No. 60, II main road, B.S.K. III Stage, III Phase, Bangalore-560085., IN
4 No.45/J, Marappa bLock,J. C. Nagar, Bangalore-560006, IN
5 Flat 202, Sandhyagiri Apartments, Kalyan Nagar, Hyderabad-500068, IN
6 7th Main, Padmanabhanagar, Bangalore- 560070, IN
7 54F, Venkatapuram, Shankernagar, Salem -636007, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 46, No 6 (1995), Pagination: 663-668Abstract
Several lensoid bodies of carbonatite occur within a wide zone of fenitisation in the granulite terrain of Kollegal taluk, Karnataka. These are emplaced along deep NNE-SSW fracture system and are associated with pyroxenite, talc-tremolite schist showing varying degree of fenitisation. The sovite and beforsite varieties show high percentage of SiO2 due to contamination during emplacement The Fe20 3 , MnO and MgO values of Ajjipuram carbonatites broadly compare with the Koratti carbonatites occurring on the eastern part ofthe mobile belt with similar tectonic history.Keywords
Carbonatites, Kollegal Taluk, Karnataka.- Archaean Meta Lamprophyres from Nuggihalli Schist Belt, Hassan District - Karnataka
Authors
1 Geological Survey of India, Jayanagar Shopping Complex, Bangalore - 560 011, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 43, No 2 (1994), Pagination: 115-137Abstract
The Archaean Dharwar greenstone belts of Karnataka predominantly consist of iron enriched tholeiitic Metabasalts, basaltic komatiites, sulphidic chert bands and argillite-graywacke sequence. In Nuggihalli schist belt, in association with mafic-ultramafic rocks, calc-alkaline lamprophyres (Spessartite-Kersantite suite), comparable with Kamblada-Yilgam of Western Australia, have been recorded for the first time. Gold mineralisation is associated with these meta-lamprophyres.
The lamprophyres, in Nuggihalli belt, is a highly banded hornblende-biotite rich quartzo-felspathic rock, forming sill like bodies at the contact of mafic-ultramafic rocks, intensely co-folded along with the enclosing rocks, recording three phases of deformation.
REE values, plotted against MORB values confirm lamprophyric affinity with increased values for Sr, K, Rb, Zr and Y. In Rock/Chondrite values plot, very pronounced increase in values of Ba, Rb, K, P, Zr and Ti is indicated while a pronounced depletion in Nb is brought out, characteristic of Calc-alkaline lamprophyres.
Search for similar rocks in many ultramafic belts in Southern Peninsular Shield will be of great Significance in working out the tectonic evolution ofthese greenstone belts and also serve as favourable target areas for gold exploration.