Open AccessGeochemistry of garnet megacrysts from the Mir kimberlite pipe (Yakutia) and the nature of prothokimberlite melt
Author(s) -
A. M. Agashev
Publication year - 2019
Publication title -
doklady akademii nauk. rossijskaâ akademiâ nauk
Language(s) - English
Resource type - Journals
ISSN - 0869-5652
DOI - 10.31857/s0869-56524865583-587
Subject(s) - kimberlite , fractional crystallization (geology) , geology , crystallization , composition (language) , geochemistry , mineralogy , melt inclusions , chemistry , volcano , mantle (geology) , linguistics , philosophy , organic chemistry
The paper presents the results of major and trace elements composition study of garnet megacrysts from Mir kimberlite pipe. On the major elements composition those garnets classified as low Cr and high Ti pyropes. Concentrations of TiO2 show a negative correlation with MgO и Cr2O3 contents in megacrysts composition. Fractional crystallization modeling indicates that the most appropriate melt to reproduce the garnet trace elements signatures is the melt of picritic composition. Composition of garnets crystallized from kimberlite melt do not correspond to observed natural garnets composition. Kimberlites contain less of Ti, Zr, Y and heavy REE (rare earth elements) but more of very incompatible elements such as light REE, Th, U, Nb, Ba then the model melt composition that necessary for garnet crystallization.