安徽歙县蛇绿岩中地幔橄榄岩的成因初探

PRELIMINARY STUDY ON THE GENESIS OF THE MANTLE OLlVINE IN OPHIOLITE OF SHE COUNTY,ANHUIO

本文研究了安徽歙县蛇绿岩内地幔橄榄岩，其Ｋ，Ｒｂ，Ｓｒ，Ｂａ，ＬＲＥＥ富集，稀土配分为ＬＲＥＥ富集型，不同于大多数造山带地幔橄榄岩。笔者认为，歙县地幔橄榄岩源岩，为轻度亏损ＬＲＥＥ尖晶石二辉橄榄岩地幔；ＬＲＥＥ富集型地幔橄榄岩，是尖晶石二辉橄榄岩地幔熔融出的８％～２５％玄武质岩浆，遭受上地幔流体交代作用的结果。地幔橄榄岩的成岩机制，是残余地幔交代成因。

This paper studied the mantle olivine in ophiolite of She county,Anhui,which was con-centrated with K,Rb ,Sr,Ba,LREE. Its rare earth partitioning was LREE-enriched type which wasdifferent from the mantle olivines of most orogenic belts. The source rock of the mantle olivine of Shecounty was believed the iherzolite mantle of light-loss LREE spinel; the mantle olivine of LREE con-centrated type was the result of eight-percent──twenty-five percent besaltic rock-magma meltedfrom the iherzolite mantle of spinel,the rock-magma later suffered the fluid metasomatism of upper-mantle. The diagenetic mechanism of mantle olivine was originated owing to the residual mantle re-placement.