| 冈底斯中段容果地区二长花岗岩锆石U-Pb年龄及其地球化学特征 |
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| 作者姓名： | 胡林 徐刚 刘大明 |
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| 作者单位： | 四川省地质矿产勘查开发局川西北地质队,绵阳 621000 |
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| 基金项目： | 中国地质调查局“西藏厅宫地区1:5万区域地质调查(编号: DD20160015)”项目资助 |
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| 摘 要： | 为确定容果地区二长花岗岩的形成时代、成因及其地质意义,对容果地区二长花岗岩进行了岩相学、LA-ICP-MS锆石U-Pb年龄及地球化学研究。结果表明: 二长花岗岩中的锆石为岩浆成因,206Pb/238U年龄加权平均值为(69±1) Ma,侵入时代属于晚白垩世; 二长花岗岩中Al2O3含量为13.83%~14.41%,Na2O含量为3.68%~3.94%,K2O含量为4.28%~4.35%, K2O/Na2O为1.08~1.18,相对富钾,铝饱和指数A/CNK平均为1.02,属弱过铝质岩石; 微量元素特征表现为相对富集Rb、U、K等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素的特征。结合区域构造演化背景,可得出在80~69 Ma之间,该区的岩浆活动并未停止,仍然持续在发生,所生成的岩体是新特提斯洋壳俯冲的岩浆产物,形成于造山环境下,形成过程贯穿整个造山运动。
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| 关 键 词： | 二长花岗岩 地球化学 LA-ICP-MS锆石U-Pb年龄 冈底斯 |
| 收稿时间： | 2019-07-31 |
Zircon U-Pb ages and geochemistry of the monzonitic granite in Rongguo area in Middle Gangdise Belt |
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| Authors: | HU Lin XU Gang LIU Daming |
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| Institution: | Northwestern Sichuan Geological Team, Bureau of Geology and Mineral Resources Exploration and Development of Sichuan Province, Mianyang 621000, China |
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| Abstract: | In order to determine the geochronology, petrogenesis and tectonic background of the monzonitic granite in Rongguo area, the authors conducted the research on petrology, LA-ICP-MS zircon U-Pb geochronology and geochemistry. The results show that the zircons from the monzonitic granite are of magmatic genesis, and the zircon 206Pb/238U dating is (69±1) Ma, belonging to the Late Cretaceous. Al2O3, Na2O, K2O contents and K2O/Na2O ratio are 13.83%~14.41%, 3.68%~3.94%, 4.28%~4.35% and 1.08~1.18 respectively. The average aluminum saturation index (A/CNK) is 1.02, belonging to the weak peraluminous series. The rocks are enriched in LILE (Rb,U,K), strongly depleted in HFSE (Nb, Ta, Ti, etc.). Combined with the study of regional tectonics, the authors insisted that magma activity had not stopped from 80 to 69 Ma. The rock mass is the magmatic product of the subduction of the Neo-Tethys Ocean, forming in the orogenic environment during the whole orogenic movement period. |
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| Keywords: | monzonitic granite geochemistry LA-ICP-MS zircon U-Pb age Gangdise |
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