Composition of fluid inclusions in olivine phenocryst from Harqin area and its tectonic implications
喀喇沁橄榄石斑晶中流体包裹体的组分特征及其构造意义

Laser Raman Microprobe has been used to detect composition of fluid inclusions in olivine phenocrysts in limburgite from Harqin area, eastern Inner-Mongolia. The results show that the fluid inclusions are mainly composed of CO 2, CO, H 2O, N 2 , H 2S, SO 2, hydrocarbons and anionic complex group to a less content,. It is considered that the fluid inclusions trapped in the early-crystallized olivine phenocryst from a slightly evolved mantle-derived magma in a relatively close system may reflect compositions of fluid in the mantle source. Thus by comparison with fluid compositions of peridotite xenoliths from Damaping area of Hannuoba, Hebei province, we suggest that the fluid composition in the mantle beneath north China craton remains stable from the Late Mesozoic to the Cenozoic. Tectonically, both of them are all formed in the lithosphere extensional environment perhaps resulted from upwelling of the asthenosphere.