Hornblende-dehydration melting in mafic rocks and the link between massif-type charnockite and associated granulites, Eastern Ghats Granulite Belt, India

摘要: A massif-type (intrusive) charnockite body in the Eastern Ghats granulite belt, India, is associated with hornblende-bearing mafic granulite, two-pyroxene and enderbitic granulite. The characterised by pervasive gneissic foliation (S1). This axial planar to folded layers of (F1 folds), indicating that protoliths were present before development S1. Two-pyroxene occur as lenticular patches disposed along hence could be syngenetic tonalitic granodioritic, metaluminous weakly peraluminous compositions relatively high Sr/Rb are consistent its derivation partial melting a protolith. Strong Y depletion, lack Sr depletion strongly fractionated REE patterns (La/Yb)N ratio, but lower HREE (Gd/Lu) fractionation marked positive Eu anomalies, suggest major residual hornblende (as well garnet), not plagioclase, dehydration source rocks. Such mineralogy broadly similar those some inclusions, which have compositional features indicative restitic nature. Quantitative modelling supports an origin for melts hornblende-rich source, although heterogeneity very likely given rather variable trace element contents charnockite. whole-rock mineral granulites them representing peritectic phase segregations hornblende-dehydration melting. clockwise P-T path implies occurred thickened continental crust undergoing decompression.