| 四川米易垭口地区前震旦纪五马箐组与其侵入岩体的锆石U-Pb年代学、Lu-Hf同位素特征及其地质意义SCIEI北大核心CSCD |
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| 引用本文： | 殷桂芹,陈友良,张宝玲,顾孟娟,王勤,姚建,尹观.四川米易垭口地区前震旦纪五马箐组与其侵入岩体的锆石U-Pb年代学、Lu-Hf同位素特征及其地质意义SCIEI北大核心CSCD[J].岩石学报,2022,38(4):1126-1148. |
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| 作者姓名： | 殷桂芹 陈友良 张宝玲 顾孟娟 王勤 姚建 尹观 |
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| 作者单位： | 成都理工大学地球科学学院, 成都 610059;核工业二八〇研究所, 广汉 618300 |
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| 基金项目： | 本文受国家自然科学基金项目（42072096）、中国核工业地质局重点科研项目（202137-3）和成都理工大学珠峰科技计划（2021ZF11413）联合资助. |
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| 摘 要： | 在扬子板块西缘断续分布有多套变质沉积岩系,厘定区内不同岩石单元的时代对于探讨扬子西缘的构造演化具有重要意义。本文对出露于扬子板块西缘米易垭口地区的五马箐组变沉积岩以及侵入其中的片麻状黑云二长花岗岩体进行了锆石LA-ICP-MS U-Pb定年和Lu-Hf同位素分析。结果表明:区内五马箐组的沉积时代介于1.19~1.01Ga,其地层归属为会理群而非康定群,位于五马箐组之下的“冷竹关组”并非变沉积地层而是一套片麻状黑云二长花岗岩体。五马箐组碎屑锆石年龄存在~1.56Ga、~2.50Ga两个主要峰值以及~1.43Ga、~1.68Ga、~1.87Ga、~2.32Ga、~2.68Ga五个次要峰值,推断其物质来源主要为扬子板块西南缘的撮科杂岩、隐伏的或还暂未发现的太古代基底岩石、同时期岩浆岩和早期变沉积岩的再循环。碎屑锆石的ε_(Hf)(t)值在~1.7Ga发生了显著变化,暗示扬子板块西缘的构造体制由陆壳汇聚向裂谷活动转变,且在~1.56Ga处于裂谷岩浆活动的峰期。花岗岩体正的ε_(Hf)(t)值反映出扬子板块西缘在~1.0Ga有一次新生陆壳生长事件,可能是格林威尔造山后的伸展塌陷构造背景下裂谷岩浆活动的产物。
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| 关 键 词： | 垭口地区 五马箐组 锆石U-Pb-Lu-Hf同位素 沉积时代 构造意义 |
| 收稿时间： | 2021/11/5 0:00:00 |
| 修稿时间： | 2021/12/22 0:00:00 |
Zircon U-Pb chronology and Lu-Hf isotopic characteristics of the Pre-Sinian Wumaqing Formation and its intrusions in Yakou area, Miyi County, Sichuan Province, and their geological significance |
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| YIN GuiQin,CHEN YouLiang,ZHANG BaoLing,GU MengJuan,WANG Qin,YAO Jian,YIN Guan.Zircon U-Pb chronology and Lu-Hf isotopic characteristics of the Pre-Sinian Wumaqing Formation and its intrusions in Yakou area, Miyi County, Sichuan Province, and their geological significance[J].Acta Petrologica Sinica,2022,38(4):1126-1148. |
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| Authors: | YIN GuiQin CHEN YouLiang ZHANG BaoLing GU MengJuan WANG Qin YAO Jian YIN Guan |
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| Institution: | College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, China;280 Institute of Nuclear Industry, Guanghan 618300, China |
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| Abstract: | There are several sets of metasedimentary rock series distributed intermittently in the western margin of Yangtze Block, it is of great significance to determine the ages of different rock units in the area for discussing the tectonic evolution. This study has conducted zircon LA-ICP-MS U-Pb dating and Lu-Hf isotopic analysis of the metasedimentary rocks from the Wumaqing Formation as well as its intrusive gneissose biotite adamellite in Yakou area, western margin of Yangtze Block. The results indicate that the sedimentary age of Wumaqing Formation in the area is between 1. 19 similar to 1. 01Ga, and the strata belongs to Huili Group rather than Kangding Group. The "Lengzhuguan Formation" under the Wumaqing Formation is not a metasedimentary stratum but a set of gneissose biotite adamellite. The detrital zircon dating of the Wumaqing Formation have two main peaks of similar to 1. 56Ga and similar to 2. 50Ga, five minor peaks of similar to 1. 43Ga, similar to 1. 68Ga, similar to 1. 87Ga, similar to 2. 32Ga and similar to 2. 68Ga, it is speculated that its sedimentary material sources are mainly from Cuoke complex, buried or undiscovered Archean basement, contemporaneous magmatic rocks and the recycled of early metasedimentary rocks in the southwestern margin of Yangtze Block. The epsilon(Hf) (t) values of detrital zircons has changed significantly at similar to 1. 7Ga, suggesting that the tectonic regime in the western margin of Yangtze Block has shifted from continental crust convergence to rift activities, and the rift magmatism has peaked at similar to 1. 56Ga. The positive epsilon(Hf) (t) values of granitic pluton implies that there was a new continental crust growth event at similar to 1. 0 Ga in the western margin of Yangtze Block, possibly is the product of rift magmatism under the extensional collapse tectonic setting after the Grenvillian Orogeny. |
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| Keywords: | Yakou area Wumaqing Formation Zircon U-Pb-Lu-Hf isotope Sedimentary age Tectonic significance |
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