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新疆金滩金矿发育一套与成矿密切相关的安山岩,对该安山岩元素质量分数和相关性进行分析。研究结果表明:安山岩中锆石结构以及Th和U的质量分数之比ω(Th)/ω(U)(0.30~1.02)均显示其为岩浆成因,锆石LA-ICP-MS U-Pb年龄为(303.65±4.8)Ma,代表安山岩形成时代;安山岩ω(Si O_2)为54.29%~69.05%,ω(Al_2O_3)为11.27%~19.46%,全碱ω(K_2O+Na_2O)为2.46%~6.81%,ω(Mg O)为3.60%~10.45%,Mg指数为46~66。安山岩轻稀土元素(LREE)富集、轻重稀土元素分异作用明显,绝大多数样品具中等Eu负异常(δω(Eu)=0.44~0.77)和轻微Ce负异常(δω(Ce)=0.93~0.98),富集K,Rb,Ba,Th和U等大离子亲石元素,相对亏损Nb和Ti等高场强元素;岩浆经历了分离结晶作用,且发生部分熔融;安山岩可能是康古尔塔格洋向南俯冲,洋壳脱水进入地幔楔,被俯冲流体交代的地幔楔部分熔融,同时产生结晶分异作用而形成,而且遭受明显的陆壳物质混染;东天山地区在晚石炭世依旧存在康古尔洋的俯冲消减作用。
A set of andesite closely related to metallogenesis was developed in the Jintan gold deposit in Xinjiang, and the elemental mass fraction and correlation of the andesite were analyzed. The results show that the zircon structure and the ratio of Th and U (0.30 ~ 1.02) in the andesite show that they are magmatic origin. The zircon LA-ICP-MS U-Pb age Is (303.65 ± 4.8) Ma, representing the age of andesite; the content of O 2 is 54.29% -69.05%, that of Al 2 O 3 is 11.27% -19.46%, and that of K 2 O + Na 2 O is 2.46% -6.81 %, ω (MgO) is 3.60% ~ 10.45%, and Mg index is 46 ~ 66. The light rare earth elements (LREEs) of andesite are enriched, and the light and heavy rare earth elements have obvious differentiation. The vast majority of samples have moderate Eu anomalies (δω (Eu) = 0.44 ~ 0.77) and slight Ce anomalies (δω (Ce) 0.98), enriched in large ion lithophile elements such as K, Rb, Ba, Th and U, relatively depleted in high field strength elements such as Nb and Ti; the magma underwent separation and crystallization and partially melted; The Dayag ocean subducted southward, the oceanic crust dewatered into the mantle wedge, partially melted by mantle wedge that was subducted by the subducting fluid and crystallized at the same time and formed crystalline disintegration and suffered obvious contamination with continental crust material. In the Late Carboniferous There is still the subduction of the Kangur ocean.