Complex Uppermost Mantle Structure and Deformation Beneath the Northwest Pacific Region
Complex Uppermost Mantle Structure and Deformation Beneath the Northwest Pacific Region
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DOI：
10.1029/2019jb017356
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
Yan Lü;Juan Li;Lijun Liu;Lian‐Feng Zhao
中科院分区：
文献类型：
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作者：
Yan Lü;Juan Li;Lijun Liu;Lian‐Feng Zhao
我们使用新开发的Pn层析成像方法获得西北太平洋地区下的高分辨率上地幔速度和各向异性结构。观测到的Pn速度与当地构造背景一致，日本海沟和松辽盆地下方Pn速度较高，千岛群岛、日本列岛-伊豆群岛、九州岛、长白山-镜泊湖火山、朝鲜半岛和日本盆地下方Pn速度较低。新的Pn速度图像描绘了日本海盆内沿着海沟和年轻海底的俯冲板块。我们的研究结果也支持了长白山、镜泊湖和中贺龙火山的热上升流的存在，在这些火山中，中国东北地区下方可能存在小规模的地幔对流。再往东，弧下的海沟平行各向异性和弧后区域内的海沟垂直各向异性都表明俯冲主导的地幔流，其中各向异性可能归因于与流动相关的应变引起的橄榄石的晶格优选取向。高精度的上地幔速度和各向异性结构提供了重要的信息，勾勒出复杂的动力学过程收敛板块边界附近。
We used a newly developed Pn tomography method to obtain high‐resolution uppermost mantle velocity and anisotropy structures beneath the Northwest Pacific region. The observed Pn velocities are consistent with the local tectonic background, where high Pn velocities are observed beneath the Japan Trench area and Songliao Basin, and low Pn velocities beneath the Kuril Islands, Japan Archipelago‐Izu Islands, Kyushu Island, Changbaishan‐Jingpohu volcanoes, Korea Peninsula, and Japan Basin. The new Pn velocity image outlines the subducting slabs along the trenches and the young seafloor within the Japan Basin. Our results also support the existence of hot upwelling feeding the Changbaishan, Jingpohu, and Chuga‐Ryong volcanoes, where small‐scale mantle convection may exist below the Northeast China region. Further east, both trench‐parallel anisotropy below arcs and trench‐perpendicular anisotropy within the back‐arc region suggest subduction‐dominant mantle flow, where anisotropy may be attributable to the lattice‐preferred orientation of olivine induced by flow‐related strain. The highly accurate uppermost mantle velocity and anisotropy structures provide crucial information outlining the complex dynamic processes near convergent plate boundaries.