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Interdisciplinary and international cooperative studies on fluid circulations in the Nankai Trough accretionary prism

南海海槽吸积棱体流体循环的跨学科国际合作研究

基本信息

批准号：
06044042
负责人：
GAMO Toshitaka
金额：
$ 9.73万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for international Scientific Research
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06044042/
关键词：
KAIKO-TOKAI subduction zone accretionary prism crustal deformation pore fluids cold seepage benthic community Nankai Trough Zenisu Ridge 深海掘削

项目摘要

The purpose of this project is to promote interdisciplinary studies on fluid circulation, crustal deformation and biological activities in the Nankai Trough accretionary prism, as part of the Japan-France cooperative KAIKO-TOKAI Project. Since the beginning of the KAIKO project in 1984, it has been known that the northwestward subduction of the Philippine Sea plate under the Eurasian plate forms a huge accretionary prism along the Nankai Trough, where circulating fluid in sedimentary layrs, accompanied with cold seepage on the sea bottom, likely plays an important role in causing large-scale crustal deformation such as big earthquakes. The KAIKO-TOKAI Project aims at elucidating geophysical, geological, geochemical and ecological characteristics of the accretionary prism, by using research vessels and submersibles. During 1994-1996,3 cruises of R/V Hakuho Maru (Ocean Research Institute, University of Tokyo), 2 cruises of R/V Tansei Maru (Ocean Research Institute, University of Tokyo), 1 cruise of R/V L'Atalante (IFREMER,France), 12 dives of DSRV Shinkai 2000 (JAMSTEC) and 8 dives of DSRV Shinkai 6500 (JAMSTEC) were devoted for this project. Results obtained during these cruises and dives have been presented and discussed at the KAIKO-TOKAI Steering Committee meetings, which were held in Japan and France once in each year. Remarkable results so far obtained are as follows : (i) another subduction was identified along the southern rim of the Zenisu Ridge by OBS observations and differential GPS measurements, (ii) Detailed crustal structure has been revealed by 120 channel seismic surveys, (iii) H_2S production by sulfate reduction (methane oxidation) was first confirmed through isotope measurements of methane dissolved in pore fluids from accretionary prism sediment, etc. The KAIKO-TOKAI project will last till the end of the 1997 fiscal year, when an international symposium will be held in Japan in order to review this project totally.

本项目是日法合作的“KAIKO-TOKAI”项目的一部分，旨在促进南开海槽沉积棱镜流体循环、地壳变形和生物活动的跨学科研究。自1984年KAIKO项目开始以来，人们已经知道菲律宾海板块在欧亚板块下的西北俯冲沿南开海槽形成了一个巨大的增生棱镜，沉积层内的循环流体伴随着海底的冷渗流，可能是造成大地震等大规模地壳变形的重要原因。KAIKO-TOKAI项目旨在通过研究船和潜水器阐明增生棱镜的地球物理、地质、地球化学和生态特征。1994-1996年期间，白湖丸号（东京大学海洋研究所）进行了3次巡航，天成丸号（东京大学海洋研究所）进行了2次巡航，阿塔兰号（法国IFREMER）进行了1次巡航，新海2000号（JAMSTEC）进行了12次潜水，新海6500号（JAMSTEC）进行了8次潜水。在这些巡航和潜水期间获得的结果已经在每年在日本和法国举行一次的KAIKO-TOKAI指导委员会会议上进行了介绍和讨论。目前取得的显著成果有：(1)通过OBS观测和差分GPS测量，在Zenisu脊南缘发现了另一个俯冲带；(2)通过120道地震调查，揭示了详细的地壳结构；(3)通过对增生棱柱状沉积物孔隙流体中溶解甲烷的同位素测量，首次证实了硫酸盐还原（甲烷氧化）产生H_2S等。KAIKO-TOKAI项目将持续到1997财政年度结束，届时将在日本举行一次国际研讨会，以便全面审查该项目。