| 勉略构造带南侧略阳地区踏坡组物源分析：来自碎屑锆石U-Pb年龄的证据 |
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| 引用本文： | 邵嘉坤, 裴先治, 李瑞保, 李佐臣, 裴磊, 刘成军, 高峰, 陈有炘, 王盟, 赵少伟. 2021. 勉略构造带南侧略阳地区踏坡组物源分析：来自碎屑锆石U-Pb年龄的证据. 西北地质, 54(3): 66-90. doi: 10.19751/j.cnki.61-1149/p.2021.03.006 |
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| 作者姓名： | 邵嘉坤 裴先治 李瑞保 李佐臣 裴磊 刘成军 高峰 陈有炘 王盟 赵少伟 |
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| 作者单位： | 1. 长安大学地球科学与资源学院, 陕西 西安 710054;;; 2. 西部矿产资源与地质工程教育部重点实验室, 自然资源部岩浆作用成矿与找矿重点实验室, 陕西 西安 710054 |
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| 基金项目： | 国家自然科学基金项目“扬子地块西北缘碧口群构造属性及与Rodinia超大陆聚合-裂解关系”（41872233）。 |
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| 摘 要： | 踏坡组位于勉略构造带南侧，是晚古生代略阳盆地的主要沉积地层，主要发育一套陆源碎屑岩，以砾岩、含砾砂岩、砂岩和粉砂岩（粉砂质板岩）为主。笔者以踏坡组碎屑岩为研究对象，对其进行LA-ICP-MS锆石U-Pb年代学分析，结合砾石组分特征，探讨其形成环境和物源特征。踏坡组岩性组合、沉积构造以及高度集中的年龄谱，指示踏坡组为近源堆积。踏坡组内大量灰岩、白云岩砾石可能来自震旦系陡山沱组和灯影组；所获得的碎屑锆石年龄可划分为2 089~1 967 Ma和2 706~2 413 Ma 2组，其中2 089~1 967 Ma年龄组锆石占总数52%，峰值年龄约2.0 Ga；2 706~2 413 Ma年龄组锆石占总数32%，峰值年龄约2.46 Ga，该2组年龄与鱼洞子杂岩和扬子板块基底构造演化相吻合。结合勉略构造带及扬子板块西北缘构造演化过程和相关年龄信息，认为踏坡组邻区的震旦系陡山沱组和灯影组、鱼洞子杂岩以及未出露的古元古代结晶基底为踏坡组主要物源区，且勉略构造带伸展裂陷可能持续到早—中泥盆世。
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| 关 键 词： | 勉略构造带 踏坡组 碎屑锆石U-Pb定年 物源分析 |
| 收稿时间： | 2020-07-05 |
| 修稿时间： | 2021-03-25 |
Provenance of the Tapo Formationin Lueyang Area: Evidence from Detrital Zircons LA-ICP-MS U-Pb Geochronology |
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| SHAO Jiakun, PEI Xianzhi, LI Ruibao, LI Zuochen, PEI Lei, LIU Chenjun, GAO Feng, CHEN Youxin, WANG Meng, ZHAO Shaowei. 2021. Provenance of the Tapo Formationin Lueyang Area: Evidence from Detrital Zircons LA-ICP-MS U-Pb Geochronology. Northwestern Geology, 54(3): 66-90. doi: 10.19751/j.cnki.61-1149/p.2021.03.006 |
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| Authors: | SHAO Jiakun PEI Xianzhi LI Ruibao LI Zuochen PEI Lei LIU Chenjun GAO Feng CHEN Youxin WANG Meng ZHAO Shaowei |
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| Affiliation: | 1. School of Earth Science and Resources, Chang'an University, Xi'an 710054, Shaanxi, China;;; 2. Key Laboratory of Western China's Mineral Resources and Geological Engineering, Ministry of Education, Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, MNR, Xi'an 710054, Shaanxi, China |
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| Abstract: | The Tapo Formation,located to the south of the Mianlue Tectonic Zone,is one of the main sedimentary stratas of the Late Paleozoic Lueyang Basin.It is characterized by a set of terrigenous clastic rocks, mainly including conglomerate, pebbly sandstone,sandstone and siltstone (siltyslate).This paper conducted the LA-ICP-MS U-Pb dating on the clastic rock from Tapo Formation and analyzed its forming environment and provenance characteristics combined with the composition of gravels.The combination of lithology,sedimentary structure and highly concentrated age data indicate that the Tapo Formation is near-source accumulation. A large quantity of limestones and dolomite gravels in the Tapo Formation may come from Sinian Doushantuo Formation and Dengying Formation in adjacent area.The available detrital zircon ages are divided into 2 groups:2 089~1 967 Ma and 2 706~2 413 Ma. The age group of 2 089~1 967 Ma accounts for 52% of the total, with a peak at 2.0 Ga; the age group of 2 706~2 413 Ma accounts for 32% of the total, with a peak at 2.46 Ga.Boththe two groups coincide with the geochronological framework of the Yangtze plate. Combined with the tectonic evolution process and related age information of Mianlue Tectonic Zone and the northwestern margin of the Yangtze plate,it is suggested that the adjacent Sinian Doushantuo and Dengying Formation,the Yudongzi Complex and the unexposed Paleoproterozoic basement in the vicinity were the main source areas of the Tapo Formation.The extension of Mianlue Tectonic Zone could continue until Early-Middle Devonian. |
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| Keywords: | Mianlue Tectonic Zone the Tapo Formation detrital zircon U-Pb dating provenance analysis |
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