| 扬子北缘西乡群大石沟组和三郎铺组凝灰岩锆石U-Pb年龄及其地质意义 |
| |
| 引用本文： | 邓奇,王剑,汪正江,江新胜,杜秋定,伍皓,杨菲,崔晓庄.扬子北缘西乡群大石沟组和三郎铺组凝灰岩锆石U-Pb年龄及其地质意义[J].吉林大学学报(地球科学版),2013,43(3):797-808,819. |
| |
| 作者姓名： | 邓奇 王剑 汪正江 江新胜 杜秋定 伍皓 杨菲 崔晓庄 |
| |
| 作者单位： | 1.中国地质调查局成都地质调查中心，成都610081;
2.中国地质科学院研究生院，北京100037 |
| |
| 基金项目： | 国家自然科学基金重点项目，国家自然科学基金面上项目，中国地质调查局计划项目 |
| |
| 摘 要： | 对采自扬子北缘西乡群大石沟组和三郎铺组的凝灰岩进行了LA-ICP-MS锆石U-Pb定年。结果表明，大石沟组和三郎铺组的凝灰岩年龄分别为（789.0±4.4） Ma（MSWD=0.66）和（760.4±4.5） Ma（MSWD=0.43）。根据已有的资料分析，西乡群的底界年龄约为820 Ma，区域上大体可与板溪群及其相当地层进行对比，为华南新元古代裂谷盆地的早期充填，其与下伏三花石群分别代表了上下2个不同的构造-沉积旋回。结合前人研究结果，华南新元古代的岩浆活动初步显示有三幕的特征，它们的峰值年龄分别约为825 Ma、795 Ma和760 Ma，其中以前两期最为明显，分别标志着裂谷盆地的开启和全面打开。笔者报道的大石沟组和三郎铺组凝灰岩分别代表了795 Ma和760 Ma两期幕式岩浆活动，它们不仅是华南新元古代幕式岩浆活动的一部分，也与华南新元古代裂谷盆地的形成密切相关，具有不可忽视的地质意义。
|
| 关 键 词： | 新元古代 西乡群 凝灰岩 锆石U-Pb年龄 地层学 幕式岩浆活动 扬子北缘 |
| 收稿时间： | 2012-11-23 |
Zircon U-Pb Ages for Tuffs from the Dashigou and Sanlangpu Formations of the Xixiang Group in the Northern Margin of Yangtze Block and Their Geological Significance |
| |
| Deng Qi,Wang Jian,Wang Zhengjiang,Jiang Xinsheng,Du Qiuding,Wu Hao,Yang Fei,Cui Xiaozhuang.Zircon U-Pb Ages for Tuffs from the Dashigou and Sanlangpu Formations of the Xixiang Group in the Northern Margin of Yangtze Block and Their Geological Significance[J].Journal of Jilin Unviersity:Earth Science Edition,2013,43(3):797-808,819. |
| |
| Authors: | Deng Qi Wang Jian Wang Zhengjiang Jiang Xinsheng Du Qiuding Wu Hao Yang Fei Cui Xiaozhuang |
| |
| Institution: | 1.Chengdu Center, China Geological Survey, Chengdu610081, China;
2.Graduate School of Chinese Academy of Geological Sciences, Beijing100037, China |
| |
| Abstract: | We present the U-Pb ages of the tuff zircons from the Dashigou and Sanlangpu Formations of the Xixiang Group at the northern margin of the Yangtze block, using the LA-ICP-MS dating analysis. Weighted mean ages are (789.0±4.4) Ma (MSWD=0.66) and (760.4±4.5) Ma (MSWD=0.43) respectively. According to existing data, the basal boundary age of the Xixiang Group should be ~820 Ma. Moreover, the Xixiang Group can be roughly compared with the Banxi Group and relevant strata in the regional scale, representing the early filling of the Neoproterozoic rift basin in the South China. Together with the underlying Sanhuashi Group, they represent the distinctive upper and lower tectonic-sedimentary circles, respectively. Combined with previous study results, it is indicated that there are three episodic magmatic activities during the Neoproterozoic epoch, with their peak ages being ~825 Ma, ~795 Ma, and ~760 Ma, respectively. The first two episodes, representing the commencing age and fully extensional age of the rift basin respectively, are more apparent than the third one, The volcaniclastic rocks from the Dashigou and Sanlangpu Formations reported represent the latter two episodic magmatic activities (~795 Ma and ~760 Ma) respectively, their geological significances should not be neglected, either because they are parts of the Neoproterozoic episodic magmatic activities or because they are closely related to the formation of the Neoproterozoic rift basin in the South China. |
| |
| Keywords: | Neoproterozoic Xixiang Group tuff zircon U-Pb age stratigraphy episodic magmatic activities Northern margin of the Yangtze block |
| 本文献已被 CNKI 万方数据 等数据库收录！ |
| 点击此处可从《吉林大学学报(地球科学版)》浏览原始摘要信息 |
| 点击此处可从《吉林大学学报(地球科学版)》下载免费的PDF全文 |
|
