东天山二红洼岩体橄榄石成分对CuNi-VTiFe复合矿化的启示
Olivine Composition of Erhongwa Complex, East Tianshan, and Its Implications to CuNi-VTiFe Composite Mineralizaion

对二红洼镁铁-超镁铁岩体Cu-Ni硫化物和Fe-Ti氧化物复合矿化的岩浆作用过程的研究有助于探讨CuNi-VTiFe复合成矿作用的机制.首先通过对两个侵入期次不同侵入相的橄榄石进行了系统的电子探针分析，其次，对岩浆作用过程的分异演化程度和硫化物熔离程度进行了模拟.研究表明，二红洼岩体的母岩浆在深部岩浆房过程中并未发生硫化物熔离作用，其中第一期岩浆作用演化程度较低，橄榄石Fo值为77.0~83.4，岩浆在运移或者就位过程中约占橄榄石1/140~1/25的硫化物熔离，造成该岩体Cu-Ni硫化物矿化；第二期岩浆作用是深部岩浆房高度分异演化的产物，橄榄石Fo值为61.1~66.7，高度的分异演化作用使Fe-Ti等成矿物质在残余岩浆中富集.两期不同演化程度的基性-超基性熔浆的先后侵位造成了二红洼岩体Cu-Ni硫化物和Fe-Ti氧化物的复合矿化.
In order to explore the magmatic process of Erhongwa mafic-ultramafic complex featuring Cu-Ni sulfide and Fe-Ti oxide composite mineralization,a systematical electron microprobe analysis of olivine from the mafic-ultramafic rocks formed by two pulses of magma is carried out in this study. Then the magmatic differentiation process and sulfide segregation are simulated. It is shown that the parental magma of two pulses of magmatic activities has not undergone sulfide mineralization and segregation in deep magma chamber. The first pulse of magma is characterized by low degree of differentiation carrying less evolved olivine with Fo contents varying from 77.0 to 83.4, about 1/140 to 1/25 of the olivine has undergone sulfide mineralization and segregation in the process of transportation. The second pulse of magma is high differentiation product in deep magma chamber, where Fe-Ti component was enriched by differentiation, and carries evolved olivine grains with Fo contents varying from 61.1 to 66.7. The intrusions of two pulses of magma with different degrees of differentiation result in Cu-Ni sulfide and Fe-Ti oxide composite mineralization of Erhongwa complex