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引用本文:高林志1 戴传固2 刘燕学1 王 敏2 王雪华2 陈建书2 丁孝忠1. 黔东地区下江群凝灰岩锆石SHRIMP U-Pb年龄及其地层意义[J]. 中国地质, 2010, 37(4): 1071-1080.
GAO Lin-zhi1, DAI Chun-gu2, LIU Yan-xue1, WANG Min2, WANG Xue-hua2, CHEN Jian-shu2, DING Xiao-zhong1. Zircon SHRIMP U-Pb dating of the tuffaceous bed of Xiajiang Group in Guizhou Province and its stratigraphic implication[J]. Geology in China, 2010, 37(4): 1071-1080(in Chinese with English abstract).
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黔东地区下江群凝灰岩锆石SHRIMP U-Pb年龄及其地层意义
高林志1 戴传固2 刘燕学1 王 敏2 王雪华2 陈建书2 丁孝忠11,2
1. 中国地质科学院地质研究所, 北京 100037;2. 贵州地矿局地质调查院,贵州 贵阳 550005
摘要:
提要:本文报道黔桂地区晚前寒武纪下江群沉积地层凝灰岩(斑脱岩)获得高精度的锆石年龄,结合侵位四堡群花岗岩锆石年龄和四堡群斑脱岩锆石SHRIMP U-Pb年龄,将下江群明确定位于新元古代晚期沉积。该年龄对为重新界定下江群时代及同期地层的区域对比和构造演化都有着重要意义。江南古陆普遍发育的晚元古代低变质绿片岩系四堡群(梵净山群、冷家溪群、双桥山群)及上覆地层丹州群(下江群、板溪群、河上镇群),两者之间的构造界面,是人们争论的主题,其时代的定位一直影响着整个江南古陆变质基底的地层划分和对比,同时制约着中国地质学家对江南造山带的地质背景和成矿条件解疑。本文通过下江群甲路组地层中斑脱岩的锆石研究,精确地测定了甲路组斑脱岩锆石年龄(814.0 ± 6.3)Ma和清水江组斑脱岩锆石年龄(773.6 ± 7.9)Ma。上述锆石年龄解决了黔桂地区新元古代晚期沉积时代问题。
关键词:  黔东地区  下江群  甲路组  清水江组  斑脱岩  锆石SHRIMP定年
DOI:
分类号:
基金项目:中国地质调查局地质大调查项目(1212010911071,1212010811033)和全国地层委员会专项资助。
Zircon SHRIMP U-Pb dating of the tuffaceous bed of Xiajiang Group in Guizhou Province and its stratigraphic implication
GAO Lin-zhi1, DAI Chun-gu2, LIU Yan-xue1, WANG Min2, WANG Xue-hua2, CHEN Jian-shu2, DING Xiao-zhong11,2
1. Institute of Geology, CAGS, Beijing 100037, China;2. Guizhou Institute of Geological Survey, Guiyang, 550005, Guizhou, China
Abstract:
Abstract:Some zircon dating data of the tuffaceous bed are reported for the first time from the Sibao and Xiajia groups in Guanxi and Guizhou. In combination with the SHRIMP U-Pb dating of the granite that intruded into the Sibao Group, the Xiajia Group is determined to be of Late Neoproterozoic. These isotopic data are very important for us to redefine the age of the Sibao Group and to conduct regional correlation of strata in the corresponding period and tectonic evolution. The Sibao Group (the same as the Fanjingshan, Lengjiaxi and Shuangqiaoshan groups) and the Danzhou Group (the same as the Xiajiang, Banxi and Heshangzheng groups), which are subsequent metamorphosed rocks well developed in the Jiangnan Orogen, formed a metamorphosed basement of the Jiangnan Continent. In the past, the Sibao Group, which constituted the main part of the Sibao Movement, was designed to Mesoproterozoic, and the determined age still affects the stratigraphic subdivision and correlation of the metamorphosed rocks in whole Jiangnan Continent and restricts the determination of the geological background and metallogenic conditions of the Jiangnan Orogen. Based on studying zircon from bentonite in the Sibao Group and overlying strata, the authors accurately dated the zircon at (814.0±6.3) Ma in the Jialu Formation, and (773.6±7.9) Ma in the Qingshuijiang Formation. The series of zircon dating data have solved the problem of the Neoproterozoic ages and also provided a new marker for the Jiangnan Orogen.
Key words:  Guizhou Province  Xiajiang Group  bentonite  zircon SHRIMP dating  “Jiangnan Orogen”