| 摘要: |
| 苏雄组为华南扬子陆块西缘新元古代康滇裂谷盆地开启初期的火山喷发产物，其形成时限可为制约裂谷盆地开启时间提供新证据。本文对川西汉源九襄地区新元古代苏雄组流纹岩进行了LA-ICP-MS锆石U-Pb同位素测定。结果显示，测试样品锆石U-Pb谐和年龄为853 ±2 Ma（N=13；MSWD=3.1），加权平均年龄为853 ±4 Ma（N=13；MSWD=2.2）。新的年龄数据表明，苏雄组的底界年龄应该下延至ca. 850 Ma，扬子西缘新元古代裂谷盆地开启时间应更改为ca. 850 Ma，与全球超级地幔柱上涌和Rodinia超大陆裂解时间基本同步。 |
| 关键词: 扬子西缘 新元古代 裂谷盆地 苏雄组 锆石U-Pb年龄 |
| DOI：10.19826/j.cnki.1009-3850.2020.07007 |
| 附件 |
| 投稿时间：2020-03-27修订日期：2020-05-06 |
| 基金项目:国家自然科学基金项目（41872120）、中国地质调查局项目（12120114067901、DD20190054） |
|
| New evidence for the opening time of the Neoproterozoic Kangdian rift basin， western Yangtze Block， South China |
| Jiang Xinsheng, Cui Xiaozhuang, Zhuo Jiewen, Jiang Zhuofei |
(1. Chengdu Center, China Geological Survey, Chengdu 610081, Sichuan, China;
2. Key Laboratory of Sedimentary Basin and Oil and Gas Resources, Ministry of Natural Resource, Chengdu 610081, Sichuan, China) |
| Abstract: |
| The Suxiong Formation is the product of volcanic eruption in the early period of the Neoproterozoic Kangdian Rift Basin on the western margin of the Yangtze Block,South China, and its forming time can provide new evidence to restrict the opening time of the Kangdian Rift Basin. Based on LA-ICP-MS, zircon U-Th-Pb dating of the rhyolite from the Neoproterozoic Suxiong Formation in Jiuxiang, Hanyuan in western Sichuan Province was carried out. The testing result shows that the zircon U-Pb concordant age is 853 ±2 Ma (N=13;MSWD=3.1) and the zircon U-Pb weighted mean age is 853 ±4 Ma (N=13;MSWD=2.2). These new age data indicate that the bottom age of the Suxiong Formation should be descended to ca.850 Ma and the opening time of the Neoproterozoic Kangdian Rift Basin on western Yangtze Block, South China should be innovated to ca.850 Ma, which is basically simultaneous with the upwelling of the super mantle plume and the breaking-up of the Rodinia supercontinent. |
| Key words: western Yangtze Block Neoproterozoic rift basin Suxiong Formation Zircon U-Pb age |
