Accurate dating for volcanic glass shards of middle Pleistocene widespread tephra determined by ITP-FT method and DC-FT method

在这项研究中，我创新了等温高原裂变径迹法(ITP-FT)和直径修正裂变径迹法(DC-FT)来确定早、中期第四纪火山玻璃碎屑的年龄。首先，有必要在标准年代样品的基础上检查计数系统的精度。显微镜反射光能有效识别每个裂变径迹的边缘，提高径迹直径的测量精度。然后，为了将ITP-FT和DC-FT测定的年龄与另一种测年方法测定的年龄进行比较，使用了2009年SO202-INOPEX邮轮采集的138个海相沉积岩芯中的特弗拉岩层。用电子探针分析仪测定了这种海相火山灰的地球化学特征。在这一点上，由ITP-FT和DC-FT测年方法确定的喷发年龄似乎与西北太平洋的火山地层学、放射性年龄、生物地层学和氧同位素地层学相吻合。因此，ITP-FT和DC-FT定年方法对第四纪早期和中期的玻璃材料的定年是有用的。

In this study, I innovated Isothermal Plateau Fission Track（ITP-FT）method and Diameter Correction Fission Track（DC-FT）method to date the volcanic glass shards of early to middle Quaternary tephra. First of all, it was necessarily to check the precision of counting system on the basis of standard dating samples. The reflecting light of microscope is effective to identify the edge of each fission track and improve the precision to measure the track diameter. Then, in order to compare age determined by ITP-FT and DC-FT to age determined by another dating method, 138 tephra beds in marine sedimentary cores, which collected by SO202-INOPEX cruise in 2009, were employed. Geochemistry of such marine tephra was determined by the electron microprobe analyzer. In this point, the eruptive age determined by ITP-FT and DC-FT dating methods seems to match with tephrostratigraphy, radiometric age, biostratigraphy, and oxygen isotopic stratigraphy in northwest Pacific. Hence, ITP-FT and DC-FT ding methods is useful to date early to middle Quaternary glass materials.