MC-ICP-MS测定铀系定年标样的^230Th年龄  

Determination of ^(230)Th Dating Age of Uranium-Series Standard Samples by Multiple Collector Inductively Coupled Plasma Mass Spectrometry

作　　者：王立胜[1] 马志邦[1] 程海[2,3] 段武辉[1] 肖举乐[1] 

机构地区：[1]中国科学院地质与地球物理研究所,新生代地质与环境重点实验室,北京100029 [2]西安交通大学全球变化研究院,陕西西安710049 [3]明尼苏达大学地质与地球物理系,美国明尼苏达州55455

出　　处：《质谱学报》2016年第3期262-272,共11页Journal of Chinese Mass Spectrometry Society

基　　金：国家重点基础研究发展973计划项目(2010CB950201)资助

摘　　要：本研究利用Neptune Plus型多接收电感耦合等离子体质谱仪(MC-ICP-MS)测定了U和Th标准溶液的同位素比值及U系定年标样的^(230)Th年龄。结果显示:CRM 112A和Harwell Uraninite-1(HU-1)的234 U/238 U原子比值分别为(52.860±0.042)×10^(-6)(δ234 U=(-38.36±0.77)‰,n=17)和(54.911±0.007)×10-6(δ234 U=(-1.04±0.13)‰,n=27),实验数据在2σ不确定范围内与国际同类实验室一致;NBS Th标准,0.6pg ^(230)Th测试精度优于3‰;5个碳酸盐标准样品76001、GBW04412、RKM-6、RKM-5和RKM-4的230 Th年龄分别为(47 520±220)y、(86 880±340)y、(130 830±550)y、(129 380±480)y和(197 970±1 590)y,与美国明尼苏达大学、西安交通大学同类实验室测定的数据具有良好的重复性。上述数据表明,本实验建立的MC-ICP-MS法230 Th定年技术可应用于中晚更新世以来碳酸盐的U-Th定年与示踪研究。Five Quaternary standard samples were dated, and isotope ratios of U and Th contained in standard solutions were measured by Neptune Plus multiple collector induc- tively coupled plasma mass spectrometry （MC-ICP-MS）. The results show that the ^234U/^238U atomic ratios of CRM 112A and Harwell Uraninite-1 （HU-1） are （52. 860±0. 042） × 10^-6 （δ^234 U = （ -38.36 ± 0.77）‰, n = 17） and （54. 911 ± 0. 007）× 10^-6 （δ^234 U= （- 1.04 ± 0.13）‰, n = 27）, respectively, which are in excellent agreement with the data previously reported by other laboratories within 2σ error; samples of 0.6 pg ^230Th （NBS Th standard） give the precisions less than 3‰; the ages of five carbonate standards are （47 520±220） y, （86 880 ± 340） y, （130 830±550） y, （129 380±480） y and （197 970±1 590） y for 76001, GBW04412, RKM-6, RKM-5 and RKM-4, respectively. These data are in accordance with the replicates measurements in the laboratories of Minnesota University and Xi＇an Jiaotong University within uncer- tainties. All errors herein quote at the 2o level, and all samples above are performed in the Uranium-series chronology laboratory of Institute of Geology and Geophysics, Chinese Acade- my of Sciences. This approach can be applied to dating various materials since late-middle Pleistocene, materials, such as speleothems, corals, deep-sea sulfides and so on.

关 键 词：多接收电感耦合等离子体质谱(MC-ICP-MS) U-Th同位素比值 ^230Th测年 U系定年标样 

分 类 号：O657.63[理学—分析化学]