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

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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.