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Research of deep structure and phenomena at the Chilean ridge subduction region

智利洋脊俯冲区深部结构与现象研究

基本信息

批准号：
17403006
负责人：
IIDAKA Takashi
金额：
$ 6.84万
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：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17403006/
关键词：
Subduction zone Seismicity Ridge Triple junction Chili trench liquid Low velocity zone

项目摘要

We deployed seismic observation at the area with the latitude of 44 S-49 S and longitude of 74W-71W. The 60 seismometers were set up at the area for two years. We use the methods of seismic tomography, surface wave analysis, and receiver function analysis. Seismic tomographic studies with P- and S- waves revealed the seismic structure at the area. The seismic structure changes from north to south along the latitude. In the northern part of the research area, the slab is subducting with dip angles of 10-20 deg. In this area, the old plate is descending beneath the other plate. At the eastern part of the area, the dip angle of the slab increase sharply. The large lateral variation of the dip angles of the subducting slab was found. At the area with steep dip angle of the slab, the dip angle of the slab is estimated to be 30 - 45 deg. The bend of the slab observed at the wide area. The region that the ridge is subducting shows a characteristic structure. The low velocity zone was detected below the slab. The ridge subducting area is also characterized to be low velocity. The velocity of the area was estimated to be 10 % lower than normal mantle velocity It is considered that the hot mantle rise up to the shallower part.The petrology studies considering thermal structure reveal a fine image of the subduction zone that the high temperature ridge is descending region.

我们在北纬44度S-49度S，经度74度-71度的地区部署了地震观测。60台地震仪在该地区安装了两年。我们使用了地震层析成像、面波分析和接收函数分析的方法。用P波和S波进行的地震层析成像研究揭示了该区的地震构造。地震结构在纬度方向上由北向南变化。在研究区北部，板块俯冲，倾角为10-20°。在这个地区，旧的板块正在下降到另一个板块的下方。在该区东部，板片倾角急剧增大。俯冲板倾角横向变化较大。在板坯倾角较大的区域，板坯倾角估计为30-45°。在宽阔的区域观察到的板的弯曲。海脊俯冲的区域显示出一种特征结构。在板条下方检测到了低速区。海脊俯冲区也具有低速特征。据估计，该地区的速度比正常地幔速度低10%，认为热地幔上升到较浅的部分。考虑热结构的岩石学研究揭示了俯冲带的良好图像，即高温脊为下降区。