Enormously large tippers observed in southwest China: can realistic 3-D EM modeling reproduce them?

IF 3 3区地球科学

Earth, Planets and Space Pub Date : 2023-01-01 Epub Date: 2023-07-14 DOI:10.1186/s40623-023-01863-y

Shan Xu, Chaojian Chen, Mikhail Kruglyakov, Alexey Kuvshinov, Rafael Rigaud, Xiangyun Hu

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引用次数: 0

Abstract

Abstract: Vertical magnetic transfer functions (tippers) estimated at a global/continental net of geomagnetic observatories/sites can be used to image the electrical conductivity structure of the Earth's crust and upper mantle (down to around 200 km). We estimated tippers at 54 geomagnetic observatories across China, aiming eventually to invert them in terms of subsurface three-dimensional (3-D) conductivity distribution. Strikingly, we obtained enormously large tippers at three inland observatories in southwest China. Large tippers are often observed at coastal/island observatories due to high conductivity contrasts between resistive bedrock and conductive seawater. However, tippers at those inland observatories appeared to be a few times larger than coastal/island tippers. As far as we know, such large tippers (reaching value 3) were never reported in any region worldwide. We perform electromagnetic simulations in 3-D conductivity models mimicking the geological setting and demonstrate that enormously large tippers are feasible and can be attributed to a current channeling effect.

Graphical abstract:

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在中国西南观察到的巨大翻车机：逼真的三维EM建模能重现它们吗？

摘要：在全球/大陆地磁观测站/站点网络上估计的垂直磁传递函数（倾翻函数）可用于对地壳和上地幔（低至约200公里）的电导率结构进行成像。我们估计了中国54个地磁观测站的倾斜度，旨在最终根据地下三维（3-D）电导率分布将其反演。引人注目的是，我们在中国西南部的三个内陆天文台获得了巨大的翻车机。由于电阻基岩和导电海水之间的高导电性对比，在海岸/岛屿天文台经常观察到大型翻斗车。然而，这些内陆天文台的翻车机似乎比沿海/岛屿翻车机大几倍。据我们所知，全球任何地区都从未报告过如此大型的翻车机（达到3）。我们在模拟地质环境的三维导电模型中进行了电磁模拟，并证明了超大倾翻器是可行的，这可归因于电流通道效应。图形摘要：

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来源期刊

Earth, Planets and Space 地学天文-地球科学综合

CiteScore

5.80

自引率

16.70%

发文量

167

期刊介绍： Earth, Planets and Space (EPS) covers scientific articles in Earth and Planetary Sciences, particularly geomagnetism, aeronomy, space science, seismology, volcanology, geodesy, and planetary science. EPS also welcomes articles in new and interdisciplinary subjects, including instrumentations. Only new and original contents will be accepted for publication.