New experimental constraints: implications for pe-trogenesis of charnockite of dioritic composition

摘要

Hornblende-dehydration melting experiments at high temperatures (> 950oC) indicate change of melt composition from tonalite/granodiorite to quartz-diorite; clinopyroxene instead of hornbl- ende as the residual phase and change in melting reaction from peritectic hornblende-dehydr- ation to eutectic clinopyroxene-orthopyroxene- plagioclase. In the light of these experimental results, petrogenesis of a charnockite pluton of homogeneous dioritic composition in the Eastern Ghats Belt, India, can be explained as melting at high-temperatures (> 950oC). Negative Sr and Eu anomalies further indicate plagioclase as a major residual phase, consistent with melt- ing at high-temperatures (> 950oC).