作　　者： (范煜坤）; (周卫健）; (侯小琳）;

机构地区： 中国科学院地球环境研究所黄土与第四纪地质国家重点实验室陕西省加速器质谱技术与应用重点实验室,西安710061 西安加速器质谱中心,西安710061

出　　处： 《地球环境学报》 2017年第4期285-291,共7页

摘　　要： ^(129)I由于具有较长半衰期,为2 Ma—80 Ma的地质定年提供了可能,因此,近几十年来,^(129)I定年的关键参数"初始值"受到了学术界关注。海洋系统中^(129)I初始值研究已较为成熟,并得到广泛认可和应用。陆地环境的认知有限,但一定程度上暗示了海陆间可能存在差异。由于环境中天然^(129)I和^(127)I来源的不同,影响地表碘同位素混合过程的环境因素是讨论陆地^(129)I初始值水平的关键,将为以后确定陆地环境的^(129)I初始值提供思路。 Background, aim, and scope Since ＇Age＇ has been playing an important role in the research on geoscience, geological dating is one of the fields that have attracted plenty of attentions and works. However, rare dating methods are available for age range from millions to tens of millions of years and each method has its applicability and limitation. Exploring and establishing a new geochronometer, especially an absolute dating method, is of great significance for geoscience research. Radionuclide iodine-129 has a long half-life （15.7 Ma）. This special feature provided a great potential of dating with range of 2 Ma--80 Ma. Since 129I decays expoentially with time, confirming the 129I/127I ratio at the preliminary stage of decay is critical to the establishment of 129I dating method. Early researches mainly focused on the initial value in marine system, while few studies on the terrestrial system are available. Interestingly, some recent analytical results coming from experiments on the pre-nuclear 129I level in the terrestrial environment showed difference. Meanwhile, some speculations are evoked by these observations and findings. Materials and methods To make a forward step of exploring the initial value of 129I on the entire earth surface and of understanding the possible mechanism of iodine isotopes circulation in the environment, we reviewed most of the relevant literatures in the past decades. Results 129I initial value started from estimations since 1960s. Experimental results in deep sea sediment gave an initial value to be 1.5× 10 ^-12. This value was widely accepted and applied for geological dating with samples formed in marine phase. Investigations on terrestrial environment including analysis of fluvial sediment, lake sediment, lignite, petrified wood and loess samples showed variations of the pre-nuclear level, most of the results being higher than that in the marine system. Illustrations were made for the indetermination and those unreliable results. Our work on the speciation analysis of 129

关 键 词： 初始值 地质定年