Genesis of Dunite from the Guli puton According to Olivine-Hosted Melt Inclusion Data

Abstract

Olivine from the dunite of the Guli pluton crystallized from olivine-melanephelinite magma at temperatures above 1260˚C according to the melt inclusion study. The melts were enriched with volatile components (S, CO2, F, H2O, slightly Cl) and contained high amount of incompatible elements. In addition, olivine hosts sporadic inclusions of picrite-basalt composition, which are close to picrite-meimechite melts preserved in chromite of dunite according to literature data. It suggests the influx of picrito-meimechite melts and the mixing of latter with melanephelinite magma were carried out during the formation of dunites in the magma chamber. Based on the indicator ratios of incompatible elements, these melts and melanephelinite magma had different sources, which were located near the undepleted mantle, at different depths and varying degrees of partial melting.