| 安徽洪镇地区董岭群片麻岩独居石SIMS U-Th-Pb定年 |
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| 引用本文： | 王继林,何斌.安徽洪镇地区董岭群片麻岩独居石SIMS U-Th-Pb定年[J].大地构造与成矿学,2017,41(4):768-775. |
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| 作者姓名： | 王继林 何斌 |
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| 作者单位： | 1. 中国冶金地质总局山东局测试中心,山东济南 250014;中国地质大学(武汉)地球科学学院,湖北武汉 430074;2. 中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州,510640 |
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| 基金项目： | 项目资助:中国科学院知识创新项目，国家自然科学基金 |
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| 摘 要： | 本文报道了安徽洪镇地区董岭群片麻岩中高精度的独居石SIMS U-Th-Pb定年结果,以~(207)Pb含量为基准对普通Pb进行校正后得到~(206)Pb/~(238)U的加权平均年龄为128.4±0.7 Ma(MSWD=1.6),~(208)Pb/~(232)Th年龄的加权平均值为128.6±0.4 Ma(MSWD=1.4)。作者认为独居石的SIMS U-Th-Pb年龄(128.4±0.7 Ma)代表了董岭群片麻岩的前进变质年龄。综合区域地质资料,提出董岭群片麻岩为新元古代沉积物在中生代经岩浆热动力接触变质的产物。这一发现不仅否定了前人提出的董岭群为前寒武纪区域变质地体的观点,而且否定了这一地区的"洪镇变质核杂岩",对进一步研究中国东部零星出露的中高级片麻岩的大地构造属性和构造演化具有借鉴意义。
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| 关 键 词： | 董岭群 独居石SIMSU-Th-Pb定年 变质时代 变质机制 变质核杂岩 岩浆底辟成因 |
SIMS U-Pb Dating of Monazite from Gneiss of Dongling Group,Hongzhen Area,Anhui Province |
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| WANG Jilin,HE Bin.SIMS U-Pb Dating of Monazite from Gneiss of Dongling Group,Hongzhen Area,Anhui Province[J].Geotectonica et Metallogenia,2017,41(4):768-775. |
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| Authors: | WANG Jilin HE Bin |
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| Abstract: | Geochronological investigation was carried out on monazite in the gneiss from the Dongling Group at Hongzhen, Anhui province. Sixteen SIMS analyses yield U contents of 334–949μg/g, Th of 1223–62990μg/g, and Th/U of 1.57–135.76. After 207-based common Pb correction, the weighted average206Pb/238U age is 128.4±0.7 Ma (MSWD=1.6), the independent Th-Pb ages averaged at 128.6±0.4 Ma (MSWD=1.4). The weighted average206Pb/238U age is interpreted as pro-metamorphic time of the Neoproterozoic Dongling Group. The dating results along with previous geological investigations suggest that the metamorphism of the Dongling Group is magmatic dynamic metamorphism. This study not only provides key evidence to deny the view that Dongling Group is Precambrian regional metamorphic block and the Mesozoic structure of Hongzhen is metamorphic core complex, but also provides a reference to research tectonic of gneisses in other areas in East China. |
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| Keywords: | Dongling Group SIMS U-Th-Pb dating of monazites pro-metamorphic time metamorphic mechanism metamorphic core complex magmatic diapiric structure |
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