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期仪器对远震事件的海底地震记录，对大洋岛弧系统下的上地幔不均匀性进行成像，并对结果进行地质解释。我们使用传统仪器对伊豆-小笠原src系统中俯冲板块上方的低Q区和所罗门弧系统下方的深部抗震俯冲板块进行了成像。利用远震P波走时相对残差模式对俯冲地震板进行了探测。然而，1 Hz 或更低的主频率超出了传统 OBS（海底地震仪）的有用范围，因此我们开发了一种配备 1 Hz 传感器和 4 GB 数据容量的新型 OBS，可进行约 3 个月的记录。我们尚未获得该系统的数据。伊豆-小笠原洋弧地壳被解释为是在俯冲早期产生的，当时存在相对较热的环境。这种环境产生了含水量丰富的博宁岩，这被解释为下地壳的重新熔化形成了花岗岩地壳。

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)。