Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions
Structure of the upper mantle in the north-western and central United States from USArray S-receiver functions
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DOI：
10.5194/se-6-957-2015
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发表时间：
2015-07
期刊：
影响因子：
3.4
通讯作者：
R. Kind;X. Yuan;J. Mechie;F. Sodoudi
中科院分区：
文献类型：
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作者：
R. Kind;X. Yuan;J. Mechie;F. Sodoudi
抽象。我们使用了超过40 000个S-接收器功能记录的USAray项目，以研究莫霍面和410公里的不连续性从美国西部的中生代美国中部的上地幔的结构。在美国西部，我们观察到岩石圈-软流圈边界（LAB），在美国东部，我们观察到克拉通的岩石圈中间不连续（MLD）和LAB。在美国北方和南方，西部LAB几乎到达大陆中部裂谷系。在这两个地区之间，南极MLD令人惊讶地从落基山脉前缘向西俯冲到塞维尔冲断带附近约200公里的深度。我们解释这些复杂的结构，在地幔岩石圈中的地震不连续的相互指状的碰撞Farallon和劳伦板块的指示。未经滤波的S-接收函数数据表明，LAB和MLD不是单一的不连续性，而是由许多小规模的层压不连续性组成，这些不连续性在较长周期滤波后才表现为单一的不连续性。我们还观察到莱曼不连续的LAB和速度减少约30公里以上的410公里的不连续。
Abstract. We used more than 40 000 S-receiver functions recorded by the USArray project to study the structure of the upper mantle between the Moho and the 410 km discontinuity from the Phanerozoic western United States to the cratonic central US. In the western United States we observed the lithosphere–asthenosphere boundary (LAB), and in the cratonic United States we observed both the mid-lithospheric discontinuity (MLD) and the LAB of the craton. In the northern and southern United States the western LAB almost reaches the mid-continental rift system. In between these two regions the cratonic MLD is surprisingly plunging towards the west from the Rocky Mountain Front to about 200 km depth near the Sevier thrust belt. We interpret these complex structures of the seismic discontinuities in the mantle lithosphere as an indication of interfingering of the colliding Farallon and Laurentia plates. Unfiltered S-receiver function data reveal that the LAB and MLD are not single discontinuities but consist of many small-scale laminated discontinuities, which only appear as single discontinuities after longer period filtering. We also observe the Lehmann discontinuity below the LAB and a velocity reduction about 30 km above the 410 km discontinuity.