中文摘要：

本文对新疆阿尔泰南缘萨尔布拉克铁矿区花岗岩体进行了锆石SHRIMPU—Pb年龄测定，获得岩体形成时代为410±4Ma（MSDW=0．88），是晚志留世-早泥盆世岩浆活动产物。岩体的年龄限定它侵入的地层时代大于410Ma，为前泥盆系而不是前人认为的中泥盆统；同时限定萨尔布拉克矽卡岩型铁矿的形成时代略晚于410Ma，为晚志留世末期-早泥盆世早期成矿。萨尔布拉克花岗岩具有富硅、偏碱性，LREE富集且分馏明显，HREE亏损且分馏不明显，中等负铕异常（δEu=0．35～0．47），微量元素Th、U、La、Ce、Nd、Zr、Hf相对富集，Nb、Ta、Sr、P、Ti相对亏损，具明显负异常的特点。Na2O／K2O集中于1附近，属于钙碱性-高钾钙碱性系列。铝过饱和指数变化于1．07～1．14，为过铝质。其微量元素地球化学特征与蒙库岩体（400～404Ma）具有很好的相似性，表明萨尔布拉克花岗岩形成于与板块俯冲有关的活动大陆边缘的陆缘弧环境中，可能是洋壳铁镁质岩石在板块俯冲过程中熔融形成，且加入了陆壳物质。

英文摘要：

SHRIMP U-Pb zircon dating on the granite from the Serbulak iron deposit district in the southern margin of Altay in Xinxiang shows that it formed at 4104 Ma （MSDW=0.88） equivalent to late Silurian or early Devonian. This age defines that the stratum intruded by the granitic pluton was formed at pre Devonian more than 410 Ma, rather than previously considered middle-Devonian and the Serbulak skarn iron deposit was formed at the end of late Silurian or the beginning of early Devonian appreciably late than 410 Ma. Geochemically, the Serbulak granite is relatively enriched in silica, alkaline, Th, U, La, Ce, Nd, Zr, Hf and markedly fractionated LREE, is predominantly depleted in Nb, Ta, Sr, P, Ti, weakly fractionated HREE and contains moderate Eu negative anomaly （δEu=0. 3540.47）. All of the Na2O/K2O ratios are around 1, indicating calc-alkaline to high K calc-alkaline series. The A/CNK ratios range from 1.07 to 1. 14, indicating perahminous granite. The apparent similarity of geochemical features on trace elements to the Mengku pluton （400-404 Ma） implies that the Serbulak pluton formed in a continental arc setting of active continental margin setting related to the subduction of plate where the mafic rocks from the oceanic crust may melt and the crust material may be trapped.