Comprehensive Study on the Dynamics of the Mid-oceanic Ridge Sysytem

本研究项目是我国第一个研究洋中脊系统的大型项目。到目前为止，日本科学家对海洋中脊系统的理解取得了巨大的进展，但却与之隔绝。该项目的主要目标之一是弥补这一差距，形成一个全国性的洋中脊系统研究小组。为此，该项目的预算被分配给每个成员科学家。我们在两年内组织了两次股东大会；第一次会议于1993年10月在伊豆的稻取举行，第二次会议于1995年2月在东京大学海洋研究所举行。此外，我们在学会会议上召开了三次科学会议；1994年在仙台举行的日本地球科学学会联合会议，1995年在东京举行的联合会议，以及1994年在旧金山举行的美国地球物理联合会秋季会议。这一研究项目的最大成果是1993年由许多成员科学家在印度洋中洋脊进行的“白虎丸号”研究巡航的成果。该地区首次观测到地震活动、地壳结构和岩浆活动的细节。在这些观测资料的基础上，我们成功地提出了三结发育的新构造模型。本项目的主要研究成果有洋中脊下地壳磁化的详细结构研究、全球地震层析分析洋中脊下熔体生成过程研究、洋中脊系统热结构研究、洋中脊系统热液活动研究等。通过两年的项目，我们认为已经达到了生动地促进日本洋中脊研究活动的初步目标。

This research project is the first large program on the mid-oceanic ridge system. So far the Japanese scientists have been isolated from the dramatic progress of the understanding on the mid-oceanic ridge system. One of the main objectives of this project is to recover this gap to form a national-wide research group on the mid-oceanic ridge system. For this purpose, the budget of the project was divided into each member scientist. We organized two general meetings during two years ; the first meeting is at Inatori, Izu on October 1993, and the second meeting is at Ocean Research Institute, University of Tokyo on February 1995. Furthermore we convened three scientific sessions in the society meetings ; 1994 Japanese Earth Science Societies Joint Meeting at Sendai, 1995 Joint Meeting at Tokyo, and American Geophysical Union 1994 Fall Meeting at San Francisco. The largest product of this research project is the results of the R/V Hakuho-maru research cruise in the Indian Ocean mid-oceanic ridges that is conducted in 1993 by many of member scientists. The detail of earthquake activities, crustal structure, and magmatism were observed for the first time in the area. We succeeded to present a new tectonic model of the development of the triple junction based on these observed data. Other major products of this research project are studies on the detailed structure of the magnetization of the crust beneath the mid-oceanic ridge, on melt generation process beneath the mid-oceanic ridge by the global earthquake tomographic analyzes, on the thermal structure of the mid-oceanic ridge system, and on the hydrothermal activities of the mid-oceanic ridge system. Through the two year project, we consider we attained the initial objective to vividly promote the activity of the mid-oceanic ridge research in Japan.