Jornal de Geologia e Geofísica
Acesso livre

Abstrato

A Geochemical Evaluation of Metamorphic Rocks from Schirmacher Oasis East Antarctica: Implications of a MORB Source

Narasimman S, Semhi K, Madhusudana Rao B, Hamdan Al-Zidi,Hilal Al-Zidi

We analyzed the Rare Earth Elements (REEs) and several trace elements of seven medium to high grade metamorphic rocks, being gneisses, a schist and a quartzite, from Schirmacher Oasis, East Antarctica. The petrographic study shows that the rock forming minerals were altered to secondary minerals. Relative to chondrite, the REEs demonstrate a fractionation with enrichment in light REEs, suggesting a mobilization of heavy REEs during crystallization of the potential protoliths. The presence of negative Eu anomalies of 0.3 to 0.86, support early fractionation of plagioclase. All samples indicate similar elemental patterns relative to chondrite leading to the conclusion that their affiliation was of the same source. However, based on patterns relative to ocean island basalt (OIB), three gneisses may be apparent to OIB. Based on the geochemical discrimination, we obtained a mid ocean ridge basalt (MORB) background as primary tectonic setting, possibly writing an alignment of a continental arc.