东天山土屋斜长花岗斑岩的成因——来自围岩的证据

The Petrogenesis of Tuwu Plagiogranite Porphyry from East Tianshan:Evidence from Wallrock

东天山土屋大型斑岩铜矿床的成因还存在较大争议。本文报道了斑岩铜矿的远矿围岩、近矿围岩和斜长花岗斑岩的主量元素、微量元素和Pb同位素地球化学特征。远矿围岩和近矿围岩具有相似的地球化学特征,属于岛弧火山岩。斑岩具有富铝、钠,富集轻稀土、亏损重稀土和高Sr/Y比值等特征。铅同位素都落在地幔演化线附近。对比研究表明,斜长花岗斑岩属于埃达克岩,为俯冲洋壳部分熔融的产物。

There is much controversial about the petrogenesis of Tuwu plagiogranite p orphyry from East Tianshan. This paper present the major elements, trace elements and Pb isotopic datas of far and adjacent wallrocks and plagiogranite porphyry itself from Tuwu cooper deposit. The far and adjacent wallrocks have similar geochemical characters and indicates that they were island are volcanics. The plagiogranite porphyry is enrichment in aluminum, sodium and light rare earth elements, but depletion in heavy rare earth elements with higher Sr/Y ratios. All samples have similar Pb isotopic composition and are all scattered along the mantle evolution line. These features show that the plagiogranite porphyry is adakite and was formed by partial melting of subducting oceanic crust, but not of lower continental crust.