Upper Mantle beneath Oceanic Island Arcs

大洋岛弧下方的上地幔

• 批准号: 07454100
• 负责人: SUYEHIRO Kiyoshi
• 金额: $ 4.48万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454100/
• 关键词: oceanic crust; OBS; upper mantle; 自然地震; 伊豆小笠原

The aim of this study was to image the uppermantle heterogeneity beneath an oceanic island arc system using ocean bottom seismographic recordings of teleseismic events by conventional instrumants and by newly developed long-period long-term instrument, amd to geologically interpret the results. We have imaged the low-Q zone above the subducting slab in the Izu-Ogasawara src system and a deep aseismic subducting plate beneath the Solomons arc system using conventional instrumants. The subducting aseismic slab was detected by using teleseismic P-wave traveltime relativeresidual patterns. However, the predominant frequencies of 1 Hz or less are beyond the useful range of conventional OBS(ocean bottom seismograph), so that we developed a new OBS equipped with 1-Hz sensor and 4 GB data capacity for about 3-month recording. We have not yet acquired data with this system yet.The Izu-Ogasawara oceanic arc crust was interpreted to have been produced in an early stage of subduction when relatively hot environement existed. This environment produced Boninites with ample water content and it is interpreted that the re-melting of the lower crust formed the granitic crust.

本研究的目的是利用传统仪器和新开发的长周期长期仪器记录的海底远震事件，对大洋岛弧系统下的上层非均质性进行成像，并对结果进行地质解释。我们使用常规仪器对Izu-Ogasawara src系统俯冲板块上方的低q带和所罗门弧系统下方的深地震俯冲板块进行了成像。利用远震纵波走时相对残差图对俯冲地震板进行了探测。然而，1赫兹或更低的主要频率超出了传统海底地震仪的可用范围，因此我们开发了一种新的海底地震仪，配备了1赫兹的传感器和4 GB的数据容量，可以记录约3个月的数据。我们还没有用这个系统获取数据。伊豆-小笠原洋弧地壳形成于相对热环境存在的俯冲早期。这一环境产生了富含水分的博宁岩，说明下地壳的再熔融作用形成了花岗岩壳。

项目成果

末廣 潔: "Continental crustal, underplantion, and low Qupper mantle beneath an oceanic island arc" Science. 271. (1996)

Kiyoshi Suehiro：“海洋岛弧下的大陆地壳、地下植被和低库普地幔”，《科学》271。（1996）

K.Suyehiro: "Continental crust, crustal underplating, andlow Qupper mantle beneath an oceanic islandarc" Science. 272. 390-392 (1996)

K.Suyehiro：“大陆地壳、地壳底板作用和大洋岛弧下方的低丘普地幔”科学。

末広: "Continental crust,crustal underplating,and low Qupper mantle beneath an oceanic island arc" Science. 272. 390-392 (1996)

Suehiro：“大陆地壳、地壳底侵和大洋岛弧下的低 Qupper 地幔”《科学》272. 390-392 (1996)。