Evolution and deformation process of the Hidaka Collision Zone, Central Hokkaido, Japan.

日本北海道中部日高碰撞带的演化与变形过程。

基本信息

批准号：
10304033
负责人：
IWASAKI Takaya
金额：
$ 23.42万
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 (A)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10304033/
关键词：
Hidaka Collision Hokkaido Arc Crust Deformation Delamination Reflection 島孤地殻

项目摘要

Our study in 1999 was concentrated in the data processing of seismic reflection data. Our data revealed a clear image of deformation style associated with the arc-arc collision' between the kuril Arc and Northeastern Japan Arc. The obtained reflection section is characterized by(1) strong westward dipping reflector in range of 3-4 sec in IWT under the eastern flank of the Hidaka Mountains,(2) eastward dipping reflector at 2 sec in TWT under the. western flank of the Hidaka Mountains.(3) westward dipping reflector at 4-6 sec in TWT under the middle part of the Hidaka Mountains,and(3) Deep events at 10-1 1 sec in TWT under the eastern edge of the profile.Data collected on off-line recorders were also completed for the refraction/wide-angle crustal study in the collision zone. A combined analysis of the seismic refection and refraction data indicates the following structural features in the surveyed area.(1) In the eastern part of the Hidaka Mountains, a material with a velocity of 5.8-6.0 km/s is almost outcr6pped.(2) The obtained velocity of 5.8-6.0 km/s is rather small as those of the middle crustal or lower crustal rocks which are expected to expose in the Hidaka Mountains. This suggests that the obducted crustal rocks are highly deformed and merged into the surrounding low-velocity upper crustal material.The seismic image obtained forms a part of the delamination-wedge structure associated with the arc-arc collision. The reflectors in the eastern part of the Hidaka Mountaines Is a upper part of the reflective lower crust of the Kuril Arc overriding westward. Our results provide important key for understanding collision process occurring in this region.

我们1999年的研究主要集中在地震反射数据的数据处理上。我们的数据揭示了与千岛弧和日本东北弧之间的弧-弧碰撞相关的变形样式的清晰图像。所获得的反射剖面的特征是：(1)日高山脉东翼下内河测量3-4秒范围内的强西倾反射体，(2)日高山脉东翼下行波测量2秒范围内的东倾反射体。 (3) 日高山脉中部下方 TWT 4-6 秒西倾反射体，(3) 剖面东缘下方 TWT 10-1 1 秒深部事件还完成了离线记录仪收集的数据，用于碰撞区的折射/广角地壳研究。地震反射和折射数据综合分析表明，测区具有以下构造特征。(1)日高山脉东部，有速度为5.8-6.0 km/s的物质几乎出露。(2 ）所获得的5.8-6.0 km/s的速度与预计在日高山脉中暴露的中地壳或下地壳岩石的速度相当小。这表明俯冲的地壳岩石发生了高度变形，并融入了周围低速的上地壳物质。获得的地震图像形成了与弧-弧碰撞相关的拆层-楔形结构的一部分。日高山脉东部的反射体是向西压倒的千岛弧反射下地壳的上部。我们的结果为理解该区域发生的碰撞过程提供了重要的关键。