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| 川西新元古界苏雄组层型剖面底部豆状熔结凝灰岩LA-ICP-MS锆石U-Pb年龄及其地质意义 |
| 卓皆文,江新胜,王剑,崔晓庄,伍皓,熊国庆,陆俊泽,江卓斐 |
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(1. 中国地质调查局成都地质调查中心, 四川 成都 610081;
2. 国土资源部沉积盆地与油气资源重点实验室, 四川 成都 610081;
3. 中国地质科学院研究生院, 北京 100037;
4. 中国地质大学(北京)地球科学与资源学院, 北京 100083) |
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| 摘要: |
| 采用LA-ICP-MS方法,首次对四川西部新元古界苏雄组层型剖面底部豆状熔结凝灰岩进行了锆石U-Th-Pb同位素测定,获得了两组谐和度极高的年龄数据:805.9±4.4 Ma(N=11,MSWD=0.58)和849.4±6.2 Ma(N=6,MSWD=0.34)。其中,805.9±4.4 Ma代表凝灰岩沉积年龄,与前人报道的苏雄组流纹岩SHRIMP锆石U-Pb年龄(803±12 Ma)高度一致,进一步约束了苏雄组底部火山喷发的起始年代。构造岩浆热事件分析表明,805.9±4.4Ma代表了华南扬子古大陆800 Ma左右的火山喷发事件;而849.4±6.2 Ma则与Rodinia超大陆初始裂解(~850Ma)的同裂谷岩浆活动相对应。 |
| 关键词: 苏雄组 豆状熔结凝灰岩 锆石U-Pb年龄 新元古代 构造岩浆热事件 |
| DOI： |
| 附件 |
| 投稿时间：2014-07-09修订日期：2014-10-28 |
| 基金项目:国家自然科学基金重点项目(41030315)和中国地质调查局项目(12120114067901、1212011121105)联合资助 |
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| LA-ICP-MS zircon U-Pb ages for pisolitic welded tuff from the bottom of the Neoproterozoic Suxiong Formation in western Sichuan and their geological significance |
| ZHUO Jie-wen, JIANG Xin-sheng, WANG Jian, CUI Xiao-zhuang, WU Hao, XIONG Guo-qing, LU Jun-ze, JIANG Zhuo-fei |
(1. Chengdu Center, China Geological Survey, Chengdu 610081, Sichuan, China;
2. Key Laboratory of Sedimentary Basin and Oil and Gas Resources, Ministry of Lard and Resources, Chengdu 610081, Sichuan, China;
3. Graduate School, Chinese Academy of Geological Sciences, Beijing 100037, China;
4. School of Geosciences and Resources, China University of Geosciences, Beijing 100083, China) |
| Abstract: |
| With the aid of LA-ICP-MS,the zircon U-Th-Pb age dating for the pisolitic welded tuff sample from the bottom of the Neoproterozoic Suxiong Formation in western Sichuan was carried out for the first time,and two groups of highly concentrated age data were obtained as follows:805.9±4.4 Ma (N=11,MSWD=0.58)and 849.4±6.2 Ma (N=6,MSWD=0.34). The younger one,i. e. 805.9±4.4 Ma,represents the age of the deposition of tuff. This age agrees well with the previously reported SHRIMP zircon U-Pb age 803±12 Ma for the rhyolites from the Suxiong Formation,and represents the initial age for the volcanic activity at the bottom of the Suxiong Formation. The study of the tectonic-magmatic thermal events shows that the age 805.9±4.4 Ma represents the ca. 800 Ma volcanic event on the Yangtze landmass in South China while the age 849.4±6.2 Ma may well correspond to the syn-rifting magmatic activity during the initial rifting of the supercontinent Rodinia at ca. 850 Ma. |
| Key words: Suxiong Formation pisolitic welded tuff zircon U-Pb age Neoproterozoic tectonic-magmatic thermal event |