| 青海南山中三叠世中酸性侵入岩的地球化学、锆石U-Pb年代学特征及构造意义 |
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| 引用本文： | 王季伟.青海南山中三叠世中酸性侵入岩的地球化学、锆石U-Pb年代学特征及构造意义[J].华南地质与矿产,2019,35(2):200-215. |
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| 作者姓名： | 王季伟 |
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| 作者单位： | 河南省地质矿产勘查开发局第三地质矿产调查院,河南郑州,450000 |
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| 基金项目： | 中国地质调查局地质调查项目"青海省共和县橡皮山地区J47E019014、J47E020014、J47E020015三幅1︰5万区域地质矿产调查 |
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| 摘 要： | 青海南山位于秦祁昆造山带结合部,大地构造位置特殊,构造演化复杂。对不同期次岩浆岩组合开展岩石地球化学和锆石U-Pb年代学研究,可为区域构造单元划分、构造阶段厘定和深部过程等提供丰富信息。对青海南山地区一些中酸性侵入岩开展岩石地球化学和锆石U-Pb年代学研究,结果如下:切如闪长岩体两个样品206Pb/238U加权平均年龄237.9±2.3Ma(MSWD=2.1)和241.0±3.2Ma(MSWD=2.4),黑马河含黑云角闪二长花岗岩体两个样品206Pb/238U加权平均年龄242.7±1.5Ma(MSWD=0.61)和239.30±2.0Ma(MSWD=1.7),表明这些侵入体的结晶年龄集中于237~242Ma,属中三叠世;地球化学上属钠质、富镁、铝不饱和的中钾钙碱性-高钾钙碱性岩石,稀土元素配分模式表现为中等程度右倾、中等程度的负铕异常。年代学和地球化学研究表明青海南山地区中酸性侵入岩形成于后碰撞环境。
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| 关 键 词： | 青海南山 中三叠世 地球化学 锆石U-PB年代学 |
Geochemistry,Zircon U-Pb Geochronology and Tectonic Significance of Middle Triassic Intermediate-acid Intrusion in Nanshan,Qinghai Province |
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| WANG Ji-Wei.Geochemistry,Zircon U-Pb Geochronology and Tectonic Significance of Middle Triassic Intermediate-acid Intrusion in Nanshan,Qinghai Province[J].Geology and Mineral Resources of South China,2019,35(2):200-215. |
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| Authors: | WANG Ji-Wei |
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| Institution: | (No.3 Institute of Geological & Mineral Resources Survey of Henan Geological Bureau,Zhengzhou 450000,Henan,China) |
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| Abstract: | Nanshan Mountain of Qinghai Province is located in the junction of Qinqikun orogenic belt. Its tectonic location is special and its tectonic evolution is complex. Geochemistry and zircon U-Pb geochronology of magmatic assemblages at different stages can provide abundant information for the division of regional tectonic units, the determination of tectonic stages and deep processes. Geochemistry and zircon U-Pb geochronology of some intermediate-acid intrusive rocks in Nanshan area of Qinghai Province have been studied. The results are as follows: the weighted average ages of 206Pb/238U for two samples of diorite body are 237.9+2.3 Ma (MSWD=2.1) and 241.0+3.2 Ma (MSWD=2.4). The weighted average ages of 206Pb/238U for two samples of Heimahe biotite-bearing hornblende monzonitic granite body are 242.7+1.5 Ma (MSWD=0.61) and 239.30 Ma(MSWD=2.4). The crystallization age of these intrusions is 237-242 Ma and belongs to Middle Triassic. Geochemically, they belong to medium-K calc-alkaline-high-K calc-alkaline rocks with sodium, magnesium and aluminium unsaturation. The distribution pattern of rare earth elements is moderately dextral and moderately negative europium anomaly. Geochronological and geochemical studies show that the intermediate-acid intrusive rocks in Nanshan area of Qinghai were formed in a post-collision environment. |
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| Keywords: | Middle Triassic lithogeochemistry zircon U-Pb chronology Nanshan area Qinghai Province |
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