Jun-Ichiro Ishibashi

Man-Yin Tsang

Satoshi Tonai

Shin Toyoda

Yuki Morono

Yuzuru Yamamoto

イシバシ ジュンイチロウ

トヨダ シン

石橋 純一郎

豊田 新

Tsang, Man-Yin

豊田, 新

トヨダ, シン

Toyoda, Shin

石橋, 純一郎

イシバシ, ジュンイチロウ

Ishibashi, Jun-Ichiro

Tonai, Satoshi

Morono, Yuki

Yamamoto, Yuzuru

AROUS Academic Repository of Okayama University of Science / 岡山理科大学学術リポジトリ

90  Ages of underthrust barite crystals of the Nankai Accretionary Prism (IODP Exp 370 Site C0023)   Man-Yin Tsang*, Shin Toyoda**, Jun-Ichiro Ishibashi***, Satoshi Tonai**** Yuki Morono*****, Yuzuru Yamamoto* *Department of Planetology, Graduate School of Science, Kobe University **Institute of Paleontology and Geochronology, Okayama University of Science  ***Kobe Ocean-bottom Exploration center, Kobe University ****Department of Global Environment and Disaster Prevention, Kochi Univeristy *****Japan Agency for Marine-Earth Science and Technology    １．Purpose of research Fluid migration in subduction zones is envisaged to be triggered by seismic events or vice versa and involves sudden changes in the formation pressure. Thus fluid migration likely contributes to the geo-logical evolution of subduction zones and also has individual effects at the small scale. Our project aims to identify the age and origin of the hot fluid that flowed in the Nankai Accretionary Prism, which formed barite mineralization and was discovered in Expedition 370 of the International Ocean Discovery Program.   ２．Summary of works at KCC and at OUS over the past year We used Kochi Core Center’s (KCC) gamma-ray detector to measure the amount of radiogenic U, Th, K, Ra isotopes in the barite and sediment samples from IODP Expedition 370. Measurement results are used for calculating the 226Ra-210Pb ages and electron spin resonance (ESR) ages of the barite, the work of which was done at Okayama University of Science (OUS). Those ages represent the timing of fluid flow in the Nankai Accretionary Prism. The 226Ra contents also give hints to the bedrock geochemistry of the fluid reservoir.  ３．Research progress Measurement is on-going. Due to the small sample sizes of some samples, measurement time could be long and we are grateful for KCC’s accommodation.   ４．Current finding The 226Ra-210Pb ages obtained from barite minerals suggest that the hot fluid flowing in the Nankai Accretionary Prism is a young event (Holocene). Ages of the barite is much younger than the hosting sedi-ment (Mid- to Late-Miocene). Such young fluid events may be related to modern seismic events of the region. Based on the data measured at KCC, we are carrying out calculations of the ESR ages to obtain ages of the older phases of the samples.    

Ages of underthrust barite crystals of the Nankai Accretionary Prism (IODP Exp 370 Site C0023)

https://ous.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3192&item_no=1&attribute_id=18&file_no=1

Ages of underthrust barite crystals of the Nankai Accretionary Prism (IODP Exp 370 Site C0023)

Abstract

Similar works

Full text

Available Versions

AROUS Academic Repository of Okayama University of Science / 岡山理科大学学術リポジトリ