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引用本文:任光明 庞维华 孙志明 尹福光. 扬子西缘黄水河群玄武岩锆石SHRIMP U-Pb定年及其地质意义[J]. 中国地质, 2013, 40(4): 1007-1015.
REN Guang-ming, PANG Wei-hua, SUN Zhi-ming, YIN Fu-guang. Zircon SHRIMP U-Pb dating of basalt from Huangshuihe Group on the western margin of the Yangtze block and its geological significance[J]. Geology in China, 2013, 40(4): 1007-1015(in Chinese with English abstract).
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扬子西缘黄水河群玄武岩锆石SHRIMP U-Pb定年及其地质意义
任光明 庞维华 孙志明 尹福光
中国地质调查局成都地质矿产研究所,四川 成都 610081
摘要:
提要:分布于龙门山逆冲推覆带内的黄水河群夹片,为一套典型的浅变质(绿片岩)岩系,局部变质程度可达低角闪岩相,其中火山岩广泛发育。本文在野外地质调查基础之上,结合岩石学、岩相学分析,对干河坝组中采集的玄武岩锆石进行SHRIMP U-Pb测年,获得(799±8)Ma和(875±12)Ma两个206Pb/238U加权平均年龄值,前者为玄武岩结晶(成岩)年龄,表明该玄武岩形成于新元古代中期,后者为捕获锆石年龄信息,代表晋宁运动的一次构造岩浆事件。结合区域上的成果资料,认为黄水河群与盐井群、苏雄组为晚青白口纪同时代沉积的地层。
关键词:  黄水河群  玄武岩  锆石SHRIMP定年  扬子西缘  新元古代中期
DOI:
分类号:
基金项目:国家自然科学基金重点项目(41030315)、中国地质调查局调查项目(1212011121110和1212011085147)及国土资源大调查项目(1212010610213)资助。
Zircon SHRIMP U-Pb dating of basalt from Huangshuihe Group on the western margin of the Yangtze block and its geological significance
REN Guang-ming, PANG Wei-hua, SUN Zhi-ming, YIN Fu-guang
Chengdu Institute of Geology and Mineral Resources, China Geological Survey, Chengdu 610081, Sichuan, China
Abstract:
Abstract:The structural clip of Huangshuihe Group, distributed along Longmenshan thrust nappe belt, is one of the typical low-grade metamorphic rock series, and some metamorphism could reach amphibolite facies, with the wide distribution of volcanic rocks. Based on field geological survey in combination with petrologic and petrographic analysis, the authors collected a sample of basalt from Ganheba Formation for zircon SHRIMP U-Pb dating, and obtained two U-Pb 206Pb/238U weighted average ages of (799±8) Ma (MSWD=0.96) and (875± 12) Ma (MSWD=0.38). The former age of (799±8)Ma represents the crystallization age of the basalt, suggesting Mid-Neoproterozoic, whereas the latter represents the age of captured zircon, signifying a tectonic-magmatic event of Jinning movement. Combined with the results of data obtained from the region, the authors hold that Huangshuihe Group, Yanjing Group, and Suxiong Formation were contemporary sedimentary strata formed in the late Qingbaikou period.
Key words:  Huangshuihe Group  basalt  zircon U-Pb dating  western margin of Yangtze block  Mid-Neoproterozoic