宫相宽,陈丹玲,木热地力·买合苏提,谭俊,李阔,任云飞,罗芬红

• 1:新疆中亚造山带大陆动力学与成矿预测自治区重点实验室新疆大学地质与矿业工程学院
• 2:大陆动力学国家重点实验室西北大学地质学系

摘要(Abstract)：

在详细野外地质调查的基础上，对秦岭岩群东段陕西丹凤大寺沟超高压变质地体中混合岩化英云闪长岩脉体开展了详细的LA-ICP-MS锆石U-Pb定年和岩石地球化学研究．结果表明：（1）英云闪长岩脉的结晶年龄为417±4Ma，内含1 832～980 Ma、506～490 Ma以及462～443 Ma等多组继承/捕获锆石年龄，其中：第一组年龄与秦岭岩群长英质片麻岩的碎屑锆石年龄一致，后两组年龄对应锆石微区Th/U比值<0.2，且分别显示了榴辉岩相和麻粒岩相变质锆石的稀土元素配分曲线特征；（2）脉体的SiO_2含量变化于64.94%～67.89%，显示富Al_2O_3(18.24%～20.33%)、高碱（Na＿2O+K＿2O=6.67%～7.54%）特征，Na＿2O/K＿2O>2,A/CNK>1.1，属过铝质中钾钙碱性系列，与I型花岗岩特征相似；微量元素方面富集Rb、Ba、K和轻稀土元素，具有明显Eu正异常，同时具有高Sr(815×10~(-6)～941×10~(-6))，低Y(2.66×10~(-6)～6.90×10~(-6))和Yb(0.26×10~(-6)～0.68×10~(-6))的特征，具有埃达克质岩石属性．综合脉体的岩石地球化学特征、脉体形成年龄（～420 Ma）明显晚于北秦岭超高压变质作用峰期变质时代（～500 Ma）而与区域第二期退变质作用时代（～420 Ma）相当的事实，尤其是脉体锆石中部分榴辉岩相和麻粒岩相继承锆石的存在，无疑表明大寺沟英云闪长岩脉是经历超高压变质的秦岭岩群变质岩石折返过程中部分熔融的产物，而且以榴辉岩的部分熔融为主，伸展背景下幔源岩浆上涌可能为本次部分熔融提供了部分热源．

关键词(KeyWords)： 英云闪长岩脉;锆石U-Pb年代学;岩石地球化学;秦岭岩群;榴辉岩;部分熔融

Abstract:

Keywords:

基金项目(Foundation): 新疆维吾尔自治区自然科学基金（2019D01C030）;; 新疆维吾尔自治区高校科研计划（XJEDU2021Y012）

作者(Author): 宫相宽,陈丹玲,木热地力·买合苏提,谭俊,李阔,任云飞,罗芬红

DOI: 10.13568/j.cnki.651094.651316.2021.04.05.0002

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