| 石榴石Lu-Hf、原位独居石U-Pb定年对多期变形的时代制约——以北祁连托勒牧场为例 |
| |
| 引用本文： | 曹汇,丛源,李广旭,许翠萍,Jeff VERVOORT,Andrew KYLANDER-CLARK.石榴石Lu-Hf、原位独居石U-Pb定年对多期变形的时代制约——以北祁连托勒牧场为例[J].岩石学报,2015,31(12):3755-3768. |
| |
| 作者姓名： | 曹汇 丛源 李广旭 许翠萍 Jeff VERVOORT Andrew KYLANDER-CLARK |
| |
| 作者单位： | 大陆构造与动力学国家重点实验室, 中国地质科学院地质研究所, 北京 100037,中国地质科学院矿产资源研究所, 北京 100037,大陆构造与动力学国家重点实验室, 中国地质科学院地质研究所, 北京 100037,大陆构造与动力学国家重点实验室, 中国地质科学院地质研究所, 北京 100037,1. 大陆构造与动力学国家重点实验室, 中国地质科学院地质研究所, 北京 100037,美国华盛顿州立大学, 普尔曼WA 99163 |
| |
| 基金项目： | 本文受国家自然科学基金项目(41202153、41472198)、公益性行业科研专项经费(201211093)、地质大调查项目(12120115027001)、中国地质科学院地质研究所中央级公益性基本业务费专项基金(J1402)和国家重点实验室自主基金(1401)联合资助. |
| |
| 摘 要： | 多期变质变形事件的精确年代限定是造山构造年代学研究的热点问题之一。本文尝试运用面理弯切轴测量技术,结合石榴石Lu-Hf和原位独居石U-Pb定年,厘定北祁连托勒牧场地区石榴石和斜长石斑晶记录的两期构造变形事件:石榴石斑晶生长记录的早期构造变形事件年代为512.3±2.7Ma;斜长石斑晶生长记录的晚期构造变形事件年代不早于481.0±2.3Ma,并推断该期构造变形水平挤压主应力方向为北东-南西。斜长石斑晶内未发现独居石,用于年代学测试的独居石颗粒均位于斜长石斑晶外基质中。显微构造分析认为,独居石生长不早于斜长石斑晶。481.0±2.3Ma的独居石U-Pb年龄,应为斜长石斑晶所记录构造变形的时代下限。结合前人锆石U-Pb定年和Hf同位素研究结果分析认为,获得的512.3±2.7Ma石榴石-全岩Lu-Hf等时线年龄,代表了祁连洋俯冲过程中石榴石的生长时间,后期变质变形作用未对石榴石的Lu-Hf同位素体系产生明显影响。结合显微构造分析,石榴石Lu-Hf定年可为早期构造变形提供有效年代学制约。
|
| 关 键 词： | 多期变形 石榴石Lu-Hf 独居石U-Pb定年 北祁连托勒牧场 |
| 收稿时间： | 8/1/2015 12:00:00 AM |
| 修稿时间： | 2015/9/16 0:00:00 |
Constrain multistage deformation using garnet Lu-Hf and monazite U-Pb dating: A case study of Tuolemuchang, North Qilian |
| |
| CAO Hui,CONG Yuan,LI GuangXu,XU CuiPing,Jeff VERVOORT and Andrew KYLANDER-CLARK.Constrain multistage deformation using garnet Lu-Hf and monazite U-Pb dating: A case study of Tuolemuchang, North Qilian[J].Acta Petrologica Sinica,2015,31(12):3755-3768. |
| |
| Authors: | CAO Hui CONG Yuan LI GuangXu XU CuiPing Jeff VERVOORT and Andrew KYLANDER-CLARK |
| |
| Institution: | State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,Institute of Mineral Resource, Chinese Academy of Geological Sciences, Beijing 100037, China,State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,1. State Key Laboratory for Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China and School of the Environment, Washington State University, Pullman, WA 99163, USA |
| |
| Abstract: | Constrain the absolute age of multiple deformation and metamorphic events is one of the hotspots in geochronology study. This study using FIAs (foliation intersection axes preserved within porphyroblasts) measurement technology, combine with garnet Lu-Hf and in situ monazite U-Pb dating to determine the two stages deformation recorded in garnet and plagioclase porphyroblast, in Tuolemuchang, North Qilian. The early deformation events recorded in garnet porphyroblast is 512.3±2.7Ma and the younger one recorded in plagioclase porphyroblast no early than 481.0±2.3Ma, with NE-SW horizontal bulk shortening. All monazite grains used for dating were in matrix, no monazite grain found in plagioclase porphyroblast. Microstructural analyses show monazite growth no early than plagioclase porphyroblast. 481.0±2.3Ma monazite U-Pb age, should be initial age of deformation recorded in plagioclase porphyroblast. Combine with the results of previous studies on Hf and U-Pb isotopic analysis, 512.3±2.7Ma garnet Lu-Hf age is considered as the growth time of garnet during the subduction process of Qilian ocean. The garnet Lu-Hf isotope system wasn't affected by younger metamorphism and deformation obviously. Combine with microstructure analysis, garnet Lu-Hf age can provide useful constrain for early stage deformation. |
| |
| Keywords: | Multistage deformation Garnet Lu-Hf Monazite U-Pb dating Tuolemuchang North Qilian |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《岩石学报》浏览原始摘要信息 |
| 点击此处可从《岩石学报》下载免费的PDF全文 |
|
