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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处理上。我们的数据显示了与千岛弧和日本东北部弧间的弧弧碰撞有关的变形样式的清晰图像。得到的反射剖面的特征是：(1)日达喀山东侧IWT的3-4秒强西倾反射层；(2)东达卡山东侧IWT的2秒东倾反射层。(3)东达卡山中段行波带4-6秒向西倾斜的反射层；(3)东缘行波带10-11秒的深部地震。对地震反射和折射资料的综合分析表明，研究区具有以下构造特征：(1)在东达卡山东部，几乎露出速度为5.8-6.0公里/S的物质，(2)获得的速度为5.8-6.0公里/S的速度，与日达卡山脉有望出露的中地壳或下地壳岩的速度相比，较小。这表明，被遮挡的地壳岩石是高度变形的，并与周围的低速上地壳物质融合在一起。所获得的地震图像形成了与弧-弧碰撞有关的拆沉-楔形构造的一部分。东达卡山东部的反射体是千岛弧向西俯冲的反射下地壳的上部。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。