Upper mantle structure beneath the Siberian craton and surrounding areas based on regional tomographic inversion of P and PP travel times
Upper mantle structure beneath the Siberian craton and surrounding areas based on regional tomographic inversion of P and PP travel times
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DOI：
10.1016/j.tecto.2010.02.011
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发表时间：
2010-04
期刊：
影响因子：
2.9
通讯作者：
I. Koulakov;N. Bushenkova
中科院分区：
文献类型：
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作者：
I. Koulakov;N. Bushenkova
我们提出了一个北亚包括西伯利亚克拉通、西西伯利亚板块、西伯利亚山脉(阿拉泰、萨扬和贝加尔)和蒙古的上地幔三维地震异常模型。我们利用Pp和P相的差异走时研究了西伯利亚地区大部分地区的深部地震结构，这些地区的台站和地震分布都不足以应用其他体波层析成像方案。为了表明基于PP-P残差的反演结果的可靠性，我们进行了各种测试，包括：(1)奇/偶数据测试；(2)棋盘和真实图案的合成测试；(3)结构清晰的其他地区的反演。此外，对于研究区域的南部，我们提出了另一种基于逆层析成像方案(ITS)的模型，该模型使用由世界各地的台站记录的位于研究区域内的事件的旅行时间。在重叠区域，这两个独立的模式总体上是一致的。本研究的主要模型是通过合并PP-P及其方案的结果而得到的。这一模型显示了西伯利亚克拉通的高速结构和西伯利亚山脉下方的低速结构之间的明显区别。西萨延新生代岩浆活动区明显与低速异常有关。在600-700公里的深度，这种低速模式位于克拉通地区之下，而在较浅的深度，它似乎沿着厚厚的克拉通岩石圈底部流向克拉通的西南边缘。
We present a model of 3D seismic anomalies in the upper mantle beneath a part of Northern Asia that includes the Siberian craton, the West Siberian Plate, the mountains framing Siberia (Altai, Sayan and Baikal) and Mongolia. We used the differential travel times of PP and P phases to investigate the deep seismic structure beneath a large part of the Siberian region, where neither stations nor earthquake distributions are sufficient to apply other body-wave tomographic schemes. To show the reliability of the results based on inversion if the PP–P residuals, we performed various tests, including: (1) tests with odd/even data; (2) synthetic tests with checkerboard and realistic patterns; and (3) inversions in other areas with clear structures. Furthermore, for the southern part of the study area, we present another model based on the Inverse Tomographic Scheme (ITS), which uses travel times recorded by worldwide stations from events located in the study area. In the overlapping areas, these two independent models are generally consistent. The main model of this study is obtained by merging the results of the PP–P and ITS schemes. This model shows a clear differentiation between the high-velocity Siberian craton and low-velocity structures beneath the mountains framing Siberia. The area of Cenozoic magmatism in Western Sayan is clearly associated with a low-velocity anomaly. At a depth of 600–700km, this low-velocity pattern is located beneath the cratonic area, while at shallower depths, it seems to flow around the bottom of the thick craton lithosphere to the SW margin of the craton.