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- Title
Occurrence of melanite garnet in syenite and ijolite-melteigite rocks of Samchampi-Samteran alkaline complex, Mikir Hills, Northeastern India.
- Authors
Saha, Abhishek; Ray, Jyotisankar; Ganguly, Sohini; Chatterjee, Nilanjan
- Abstract
The Samchampi-Samteran alkaline complex constitutes a part of the ultramafic-mafic-alkaline-carbonatite complexes of Shillong Plateau and Mikir Hills and represents one of the differentiation centres of Sylhet Trap magmatism which manifests the initiation of Kerguelen plume activities on the Indian subcontinent. A detailed petrographic study reveals that Ti-rich andradite garnets occur in syenite and ijolite- melteigite rocks of the Samchampi-Samteran alkaline complex, Mikir Hills, northeastern India. The Ti-rich garnets have formed at the expense of clinopyroxene in both syenite and ijolite-melteigite rocks due to alkali metasomatic reactions between earlier formed mafic mineral and late-stage fluids. Distinct mineral- chemical characters supported by electron microprobe data classify the Ti-rich andradite garnets as melanite. Melanite garnets from the Samchampi-Samteran alkaline complex are chemically akin to those from different alkaline complexes from India and abroad, and their unique compositional parameters clearly reflect the effects of alkali metasomatism on the mineral paragenesis of an alkaline complex like Samchampi- Samteran.
- Subjects
SHILLONG (India); NORTHEASTERN India; SYENITE; GARNET; ANDRADITE; ULTRABASIC rocks; ELECTRON probe microanalysis; CHEMICAL reactions; PARAGENESIS
- Publication
Current Science (00113891), 2011, Vol 101, Issue 1, p95
- ISSN
0011-3891
- Publication type
Article