地质通报2017，Vol.36Issue(8)：1393-1406,14.
桂北地区丹洲群碎屑锆石LA-ICP-MS U-Pb年龄和Hf同位素特征及其地质意义
LA-ICP-MS U-Pb dating and Hf isotopes of detrital zircon grains from siltstone of Danzhou Group in northern Guangxi and their geological significance
摘要
Abstract
This paper reports LA-ICP-MS U-Pb dating and Hf isotopes for detrital zircon grains of siltstone from Gongdong Formation at the top of the Danzhou Group.The majority of zircon grains are transparent,euhedral and prismatic crystals with oscillatory zoning in CL images and have high Th/U ratios of 0.2～2.4,indicating an igneous origin for the zircon.The 206Pb/238pb age distributions for the detrital zircon grains mainly range from 730Ma to 769Ma and 771Ma to 850Ma,and ε Hf(t) and two-stage Hfmodel ages (TDM2) range from-18.4 to 11.4 and from 1020Ma to 2812Ma,respectively.Moreover,there are some detrital zircon grains with relatively older ages with 206Pb/238pb ages from 1910Ma to 3140Ma,and ε Hf(t) and TDM2 from-13.6～3.4 and 2740～3635Ma,respectively.Combined with previous researches,the authors infer that the maximum depositional age of the Gongdong Formation from Danzhou Group is 706± 10Ma.The source region was predominated by Neoproterozoic magmatic rocks from Yangtze Block (ca.750～830Ma) with the mixture of minor Archean magmatic rocks.There was developed the Greenville movement in South China resulting from the assembly ofR odinia supercontinent.In addition,on the basis of the ε Hf(t) and TDM2 data of the detrital zircon grains,the authors hold the existence of three stages for the crust growth in the study area:①3.64Ga to 3.25Ga,with the juvenile crust at 3.64Ga;②2.98Ga to 2.37Ga;③2.19Ga to 1.28Ga.关键词
桂北丹洲群/碎屑锆石LA-ICP-MS U-Pb定年/Hf同位素/Rodima超大陆/地壳生长Key words
Danzhou Group in northern Guangxi/detrital zircon LA-ICP-MS U-Pb dating/Hf isotope/Rodinia supercontinent/crust growth分类
天文与地球科学引用本文复制引用
寇彩化,刘燕学,李廷栋,黄河,张恒..桂北地区丹洲群碎屑锆石LA-ICP-MS U-Pb年龄和Hf同位素特征及其地质意义[J].地质通报,2017,36(8):1393-1406,14.基金项目
国家自然科学基金项目《江南造山带西段桂北新元古代基性-超基性岩岩石成因研究及其对构造演化的约束》(批准号:41402052)、中国地质科学院基本科研业务《湘西新元古代基性-超基性岩岩石年代学及成因研究》(编号:J1602)和中国地质调查项目《中国区域地质志》(编号:1212011120117) （批准号:41402052）
