Geochemistry and Tectonic Significance of the Amphibolites of Etalin Formation in Trans Himalayan Belt, Arunahcal Pradesh, India

Authors: Debapriya Adhikary, Sebabrata Das, Chinchu S.V.

Country: India

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Abstract: On the basis of lithological variation and mineralogical variation, depending on relative proportion of hornblende, quartz and mica content, the Etalin Formation has been subdivided into four members viz Hornblende chlorite schist, Banded hornblende chlorite schist, Quartzite and Carbonatite with CaO content varies from 29.8 wt% to 41.65 wt%. The poikiloblastic texture of garnet and hornblende and the random orientation of hornblende laths is suggestive of their formation due to contact metamorphism and is attributed to intrusive nature of Lohit Granitoid with in the Etalin Formation. The lateral extent of different members in the eastern side is inferred and extrapolated due to complete inaccessibility of the area. The quartzite bands do not have much lateral extent towards west and it can be inferred that they exist as isolated patches. The presence of laths of hornblende in the banded hornblende chlorite schist member which are found to be floating in the mass of quartz and mica, may have formed in phase of retrogression. Chemical analysis of major oxides indicates that the composition of hornblende chlorite schists and banded hornblende chlorite schists is basaltic to dacitic, calc-alkaline and metaluminous. Trace element concentration indicates that these are calc-alkaline basalts which indicate volcanic arc setting. Mineral chemistry of Etalin Formation also suggests that the protolith is basic in nature.

Keywords: Mineral Chemistry, Amphibolite, Etalin Formation

Paper Id: 230616

Published On: 2024-05-03

Published In: Volume 12, Issue 3, May-June 2024

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