新疆东天山二红洼岩体岩浆演化特征与成矿潜力分析

Magmatic Evolution and Mineralization Potential of the Erhongwa Intrusion in East Tianshan Mountains,Xinjiang

二红洼岩体位于康古尔-黄山韧性剪切带东段,主要由含长二辉橄榄岩、橄榄辉长岩、辉长苏长岩和淡色辉长岩组成。岩石相对富集LREE,亏损高场强元素(Nb、Ta、Ti)。岩体原生岩浆为普通拉斑玄武岩(MgO=7.3%)。通过对元素地球化学和Nd、Sr、Pb同位素体系研究证明,岩浆源区以软流圈物质为主,混入了少量富集岩石圈地幔组分,岩浆遭受了约5%上地壳物质的混染。与同岩带典型含矿岩体对比研究表明,岩体在岩石组合、原生岩浆性质、同化混染程度等方面存在显著差异,这些因素可能制约了成矿潜力。

Erhongwa intrusion lies in the eastern part of Kongguer-Huangshan fault belt.It consists of pl-bearing iherzolite,olivine gabbro,gabbronorite and leucogabbro.Most of these rocks are slightly enriched in LREE and depleted in HFSE（Nb,Ta and Ti）.The primary magma of this intrusion may be ordinary tholeiite（MgO=7.3%）.Element geochemistry and Nb,Sr,Pb isotope characters suggest that this magma source is composed of asthenosphere components,mixed with a small amount of lithospheric mantle components,and this magma was subjected to becontaminated about 5% by contiental crust.Compared with others intrusion in this mafic-ultrumafic belt,the Erhongwa intrusion has some significant differences in rock association,primary magma nature and assimilation,which may restrict the mineralization potential in this area.