碳酸岩与铂族元素地球化学

碳酸岩（carbonatite）被视为一种研究大陆地幔地球化学的“探针岩石”，通过对这类岩石的研究，在探讨地幔组成与演化、地幔交代作用与不均一性以及岩浆形成的动力学背景、岩浆来源及演化和有关矿产的成矿作用等方面，具有重要的理论意义和实际价值。铂族元素（Platinum—group elements，简称PGE）在研究核-幔分异、地幔组成与演化以及幔源岩石（主要为基性-超基性岩）形成的大地构造背景、岩浆起源及演化，以及探讨K／T界线与陨石撞击事件等方面具有重要意义。本文在概述国内外碳酸岩和PGE地球化学研究现状的基础上，结合地质事实和地球化学研究成果，认为碳酸岩熔体具有一定携带PGE的能力，可利用PGE地球化学来探讨碳酸岩的源区特征和岩浆形成与演化过程；同时指出，碳酸岩PGE地球化学研究过程中还存在许多悬而未决的科学问题。

Carbonatites and Geochemistry of Platium-Group Elements

Carbonatites are regarded as a kind of probe rocks to study the geochemistry of the continental mantle. The studies of this type of rocks have important theoretical and practical significances on such aspects as the mantle composition and evolution, mantle metasomatism, mantle heterogeneity, geodynamic setting of forming magmas, magma source and evolution, and related mineralization. Platinum-group elements (PGE) have crucial implications on studying the differentiation of the core and mantle, mantle composition and evolution, tectonic settings of mantle-derived rocks (mainly mafic and ultramafic rocks) , the origin and evolution of magmas, the interface of K/T and meteorite impact events, and so on. At present geochemical study of the platinum-group elements of carbonatites is rarely known. Based on a summary of the research status on geochemistry of platinum-group elements and carbonatites, combined with geological facts and geochemical conclusions, we conclude that carbonatites are capable of carrying platinum-group elements so that the PGE geochemistry of carbonatites can be used to trace the characteristics of their mantle source region and the processes of magma formation and evolution. At the same time, there are many unsolved scientific problems on geochemistry of the platinum-group elements of carbonatites.