赣中相山元古宙斜长角闪岩的矿物学、岩石学特征及同位素地球化学研究

MINERALOGY, PETROLOGY AND ISOTOPIC GEOCHEMISTRY OF THE PROTEROZOIC AMPHIBOLITES FROM XIANGSHAN,CENTRAL JIANGXI PROVINCE

通过岩石学、矿物学、稀土及微量元素地球化学和Nd、Sr、Ph、O同位素组成的研究，确定相山斜长角闪岩的原岩为基性火山岩（玄武岩），井形成于岛弧环境，主要衍生于弱亏损地幔源区，并受到地壳物质某种程度的混染。造岩矿物成分具有低角闪岩相变质作用的特征，表明它们是低角闪岩相变质作用的产物，变质作用的温压条件为550℃±，0．69Gpa±。根据斜长角闪岩原岩的形成年龄（1113Ma）及变质年龄值（726．6Ma）结合其地质地球化学特征，确认赣中相山地区存在元古宙岛弧。

On the basis of comprehensive study of Petrology, mineralogy, trace element and isotopic geochemistry for the Xiangshan amphibolites, we suggest that the protolith of the amphibolites was basalts formed in an island-are tectonic setting. The basaltic magma was derived from a slightly depleted mantle source with a small amount of crustal contamination. Assemblage of the rock-forming minerals indicates that these amphibolites underwent a metamorphism of low-grade amphibolite facties. The temperature and pressure for the metamorphism are determined to be 550℃ and 0.69 Gpa, respectively. According to the formation age (1113 Ma) and the subsequent metamorphic age (726.6 Ma) the basalts as well as the geological and geochemical features of these amphibolites, a tectonic model of Proterozoic oceedc island-are setting is proposed for the Central Jiangxi Province.