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位于新疆西天山北缘的博罗科努晚古生代岛弧带出露有大量的中酸性侵入体分布有一系列与斑岩-夕卡岩型铁铜多金属矿床,本文对该岛弧带中部阔库确科夕卡岩型铁铜矿区与成岩相关的花岗岩和闪长岩进行了元素地球化学、矿物化学和锆石U-Pb同位素年代学研究。岩体富Si和K,A/CNK<1.1,属于准铝质-弱过铝质I型花岗岩。岩石富集轻稀土和大离子亲石元素,亏损重稀土和高场强元素,具有明显的Eu负异常,表现出俯冲带岩浆作用特征。岩石Nb/Ta比值(9.8~13.3)、黑云母Mg O质量分数(9.45%~10.99%)和角闪石M值(0.73~0.85)均介于壳源型和幔源型之间,表明其形成具有壳幔源物质参与。锆石LA-ICP-MS U-Pb同位素定年结果显示,花岗岩和闪长岩形成时代相近,二者加权平均年龄分别为(362.3±2.8)Ma和(363.4±3.7)Ma,Rb-(Yb+Nb)和Rb-(Yb+Ta)图解显示岩石几乎都为火山弧花岗岩,(Sr/Y)-Y和(La/Yb)N-YbN图解显示它们均属经典岛弧岩石,说明岩体形成于晚泥盆世板块俯冲的大地构造背景下。锆石饱和温度(705~760℃)和黑云母形成温度(710~750℃)显示岩体为下地壳部分熔融的产物,Th/Ce-Sr/Th和Th/Yb-Sr/Yb的关系反映成岩流体来自于沉积物脱水,Harker图解以及Ba、Sr、P、Ti和Eu等元素的显著亏损,暗示结晶分异作用的发生。我们认为,晚泥盆世时期,在北天山洋向伊犁板块俯冲的构造背景下,俯冲带沉积物脱水产生的流体引发下地壳发生部分熔融,伴随着地幔物质的加入以及一定程度的结晶分异作用,形成了阔库确科矿区岩体。
A large number of intermediate-acidic intrusions have been found in the Archean Paleozoic arc belt of the Borokunu, located in the northern margin of western Tianshan Mountains, Xinjiang, with a series of porphyry-skarn type Fe-Cu polymetallic deposits. In this paper, Indeed, the elemental geochemistry, mineral chemistry and zircon U-Pb isotopic dating of diagenetic-related granites and diorites in the Craton Skarn type iron-copper mine are studied. The rock mass is rich in Si and K, with A / CNK <1.1 and belongs to the quasi-Al-weak Al-I granite. The rocks are enriched in both light rare earths and large ion lithophile elements, depleted in heavy rare earth elements and high field strength elements, have obvious Eu anomalies and show subduction magmatism. The ratios of Nb to Ta (9.8 ~ 13.3), biotite MgO (9.45% ~ 10.99%) and amphibole M (0.73 ~ 0.85) are between the crustal and mantle source, The formation of a mantle of mantle material involved. The results of dating of U-Pb zircons by LA-ICP-MS show that the ages of granite and diorite are similar, with the weighted average ages of (362.3 ± 2.8) Ma and (363.4 ± 3.7) Ma and Rb- (Yb + (Rb- (Yb + Ta)) shows that almost all of the rocks are volcanic arc granites. The (Sr / Y) -Y and (La / Yb) N-YbN diagrams show that they are all classic island arc rocks, In the late Devonian plate subduction of the tectonic setting. The relationship between Th / Ce-Sr / Th and Th / Yb-Sr / Yb is shown by the zircons saturation temperature (705 ~ 760 ℃) and biotite formation temperature (710 ~ 750 ℃) Diagenetic fluids come from sediment dehydration, Harker diagrams and significant depletion of elements such as Ba, Sr, P, Ti and Eu, suggesting the occurrence of crystallization divergence. In the late Devonian period, the fluids generated by the dewatering of sediments in the subduction zone triggered a partial melting of the lower crust under the tectonic setting of subduction of the North Tianshan ocean to the Yili plateau, with the addition of mantle materials and some degree of crystallization differentiation The role of the formation of a large library Kuk Ke rock area.