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

ITP-FT法和DC-FT法对中更新世广泛分布的火山灰火山玻璃碎片的精确定年

• 批准号: 21740365
• 负责人: AOKI Kaori
• 金额: $ 3.16万
• 依托单位: Rissho University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Young Scientists (B)
• 财政年份: 2009
• 资助国家: 日本
• 起止时间: 2009 至 2012
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-21740365/
• 关键词: テフロクロノロジー; 第四紀学; 年代測定; 火山灰編年; 第四紀; 火山ガラス; フィッショントラック; ITP-FT; DC-FT

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.

本研究创新了等温高原裂变径迹（ITP-FT）法和直径校正裂变径迹（DC-FT）法，对早至中第四纪火山玻璃碎片进行了年代测定。首先，必须在标准定年样品的基础上检查计数系统的精度。利用显微镜的反射光有效地识别出每条裂变径迹的边缘，提高了径迹直径测量的精度。然后，为了将ITP-FT和DC-FT确定的年龄与另一种测年方法确定的年龄进行比较，使用了2009年SO202-INOPEX巡航收集的138个海相沉积岩心的tephra层。用电子探针分析仪测定了该海洋菌的地球化学特征。在这一点上，用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地层、辐射年龄、生物地层学和氧同位素地层学相匹配。因此，ITP-FT和DC-FT测定方法是有用的早期到中期的第四纪玻璃材料。