地幔流体与成矿作用

THE MANTLE FLUID AND METALLOGENY

地球内部流体的活动乃是形成各种矿床的必要条件，是导致矿物聚积和金属成矿作用的前提。随着地球科学的进展，作为地球内部流体的重要组成部分，地幔流体受到越来越多的重视。本文在解剖世界首例白云鄂博地幔流体交代稀土矿床的基础上，初步总结了地幔流体与成矿作用的基本问题。

Generally,the activity of various fluids in Earth’s interior has been commonly consid-ered as the fundamental condition for the mineralization and metallogeny.With the ad- vance in Earth sciences,the mantle fluid has been attracted attention for its special func-tion.Recent years a mantle fluid replacement ore deposit in China was discovered by theauthors. The Bayan Obo in Inner Mongolia,northern China is the world’s largest known rareearth elements(REE)ore deposit.In view of the overall low Sr isotopic ratios of REEminerals,the metallogenetic elements,REE and Nb etc. are thought to be derived frommantle source and a large involvement of older crustal material can be ruled out.The car-bon and oxygen within the REE fluocarbonate minerals are composed of mantle C and O;meanwhile,the surphur in the associated surphides belong to the meteorite S,according totheir isotopic composition. It is suggested that the REE ore- forming solution was not thehydrothermal brine from crustal source,but would be the mantle fluid that has never beendocumented in the classical works of economic geology and traditional metallogeny. Hence,it might be a unique mantle fluid metasomatic REE ore deposit in the world. In this paper,the basic problems on the mantle fluid and related metallogeny havebeen summarized.