云南金宝山岩体岩浆起源的微量元素模式分析

MAGMA GENERATION OF THE JINBAOSHAN ULTRAMAFIC INTRUSION,YUNNAN

金宝山镁铁-超镁铁岩体是峨眉山大火成岩省一个典型的岩浆Cu-Ni-PGE成矿岩体。在根据成岩机制概算原始岩浆微量元素含量的基础上,通过模式计算,表明原始岩浆强不相容元素相对富集型式不可能由现有原始地幔或亏损地幔模型的单一源区熔融或融体混合作用形成,原始岩浆起源于类似OIB源的地幔柱高程度熔融,熔融程度在20%左右。

The Jinbaoshan intrusion, located in Midu County, Yunnan, hosts the largest independent PGE deposit in China. Based on the estimation of trace element contents of primary magma and the mechanism of magma evolution, modeling of several kinds of possible mantle melting had been attempted in this paper. For lower incompatible trace element contents but significant fraetionation pattern in order of element incompatibilities, the modeling shows that the primitive magma of the Jinbaoshan intrusion would not originate by melting of either primitive mantle （PM） or N-MORB source （DM）, or any mixing of the two. But it can reconcile with the modeling of high-degree partial melting （about 20% ） of the source of OIB. So, the primitive magma of the Jinbaoshan ttltramafic intrusion originated from rnanfle plume.