Ree Distributions in Basaltic Anorthosites from the Holenarasipur Greenstone Belt, Karnataka, South India

摘要: Abstract Extremely fine-grained meta-anorthosites to anorthositic meta-basalts are found as sheets and lenses amongst meta-peridotitic komatiites, serpentinites amphibolites of the c. 3.5 by Holenarasipur greenstone belt in Karnataka State. Their REE patterns show slight enrichment LREE relative HREE, La varying between 12 7 times HREE 3 4 chondritic abundances, average (Ce/Yb)N ratio is 2.1. Eu content variable, Eu/Eu* ranging from 1.2–9.0 showing a strong negative correlation with modal amphibole. In such respects these supracrustal rocks differ greatly high-grade similar major element chemistry West Greenland NW Norway, but remarkable resemblance lunar highland basalts. This confirmed close textural other geochemical similarities. The relatively unfractionated nature basalts suggests that they may represent basalt melts within which small amounts plagioclase accumulation has occurred. origin restricted data two possibilities: (a) degrees partial melting very hydrous mantle peridotite; (b) large olivine orthopyroxene fractionation peridotitic komatiite magmas.