| 广西梧州思委银矿区花岗岩的岩石成因：锆石U-Pb测年、岩石地球化学和Hf同位素约束 |
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| 引用本文： | 张,鲲.广西梧州思委银矿区花岗岩的岩石成因：锆石U-Pb测年、岩石地球化学和Hf同位素约束[J].地质与勘探,2018,54(1):102-111. |
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| 作者姓名： | 张 鲲 |
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| 作者单位： | 武汉地质矿产研究所，湖北 武汉； 中国地质大学（武汉）地球科学学院，湖北 武汉 |
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| 基金项目： | 中国地质调查局地质矿产调查评价专项项目（编号：1212011085405，1212011085416，12120113067200） |
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| 摘 要： | 本文对广西梧州思委银矿区思委岩体中细粒黑云母二长花岗岩进行了系统的锆石U-Pb年代学、岩石地球化学和Hf同位素分析研究,以深入探讨其岩石成因。LA-ICP-MS锆石U-Pb定年获得了思委岩体黑云母二长花岗岩成岩年龄为165±1Ma。思委岩体黑云母二长花岗岩为一套弱过铝质高钾钙碱性系列花岗岩,富集U、K、Pb等元素,亏损Nb、Ta、P、Ti等元素;球粒陨石标准化REE配分模式为右倾斜配分模式,轻重稀土元素分异强烈,富集轻稀土元素,重稀土元素平坦分布。锆石Hf同位素分析花岗岩锆石ε_(Hf)(t)值分布在-15.9~8.7之间,Hf同位素二阶段模式年龄(t2DM)在652~2255Ma之间,表明岩浆源区既有直接源于亏损地幔分异的新生地壳的迅速重熔,也有不同比例的古老地壳的混合作用。花岗岩成岩可能是受古太平洋板块持续俯冲作用影响,焊接板片开裂形成的岩浆上侵。
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| 关 键 词： | 钦杭成矿带 思委 锆石U-Pb定年 Hf同位素 |
| 收稿时间： | 2016/6/14 0:00:00 |
| 修稿时间： | 2017/5/8 0:00:00 |
Petrogenisis of granites in the Siwei area of Guangxi: Constraints from zircon U-Pb chronology, petrochemistry and Hf isotopes |
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| Zhang Kun.Petrogenisis of granites in the Siwei area of Guangxi: Constraints from zircon U-Pb chronology, petrochemistry and Hf isotopes[J].Geology and Prospecting,2018,54(1):102-111. |
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| Authors: | Zhang Kun |
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| Institution: | Wuhan Institute of Geology and Mineral Resources, Wuhan, Hubei; School of Earth Sciences, China University of Geosciences (Wuhan), Wuhan, Hubei |
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| Abstract: | This work explores the genesis of the medium-fine grained biotite granite in the Siwei Ag-polymetallic deposit of Wuzhou, Guangxi by zircon U-Pb isotope chronology, petrochemistry and Hf isotopes. LA-ICPMS zircon U-Pb dating yields a crystallization age of 165±1 Ma for the Siwei medium-fine grained biotite granite. This granite is a peraluminous high-K-calc-alkaline intrusive rock. It is characterized by high U, K, and Pb content and depleted Nb, Ta, P and Ti. The REE distribution patterns are strongly LREE-enriched and HREE-depleted. The Hf isotopes show a two-stage model age ranging from 652 to 2255 Ma. It indicates that its parental magma was derived from the rapid remelting of the Cenozoic crust which stemmed directly from the depleted mantle as well as mixed ancient crust. The formation of granites may be associated with the subduction of the ancient Pacific Plate, where the welded slab broke leading to high high-K calc-alkaline magmatic intrusion. |
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| Keywords: | Qinzhou-Hangzhou metallogenic belt Siwei zircon U-Pb dating Hf isotopes Wuzhou Guangxi |
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