新疆东天山黄山东岩体岩石地球化学特征与岩石成因
Geochemistry and petrogenesis of Huangshandong intrusion, East Tianshan, Xinjiang
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摘要: 黄山东岩体位于东天山北部的土墩-黄山-图拉尔根镁铁-超镁铁质岩带中段，受康古尔塔格-黄山深大断裂控制，是由辉长闪长岩、角闪辉长岩、橄榄辉长岩、辉长苏长岩及二辉橄榄岩组成的复式岩体。主量元素化学组成部分属拉斑玄武岩系列，也有部分属钙碱性系列。大部分岩石相对富集LREE、适度亏损高场强元素（Nb、Ta、Ti）。元素地球化学和Nd、Sr、Pb同位素体系证明，岩浆遭受了5%~8%的中-上地壳物质的同化混染作用。岩浆源区由被消减板片交代的地幔楔物质和软流圈地幔物质组成。岩石圈根部拆沉和软流圈地幔上涌过程中生成了黄山东岩体。富铁硅酸盐的分离结晶作用对硫化物富集并分凝起到了关键性作用，成矿过程应该是岩浆自身演化过程的有机组成部分。Abstract: Huangshandong intrusion is located in the centre segment of Tudun-Huangshan-Tulaergen mafic-ultramafic rock belt, the northern of East Tianshan, and controlled by Kangurtag-Huangshan ductile sheer zone. It is a multiple intrusion and composes of gabbro diorite, hornblende gabbro, olivine gabbro, gabbronorite and lherzolite. Some belong to the tholeiitic series; others are calc-alkaline series in petrochemical composition. Most of the rocks are slightly enriched in LREE, moderately depleted in HFSE (Nb, Ta, Ti). Element geochemistry and Nb, Sr, Pb isotope characters suggest that the magma was subjected to comtaminated about 5%~8% by upper-intermediate continental crust. The magma source is composed of wedge matasomasised by subducting slab and asthenosphere components. Huangshandong intrusion is the result of lithospheric delamination at the root and the upwelling of asthenosphere components. The fractional crystallization of Fe-rich silicate mineral could be responsible for sulphur saturation as well as sulfide melt segregation, and mineralization should be partly self-evolution of magma.
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Key words:
- Petrogeochemistry /
- Magma evolution /
- Mineralization /
- Huangshandong intrusion
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