Electrical and seismological structure of the martian mantle and the detectability of impact-generated anomalies
Electrical and seismological structure of the martian mantle and the detectability of impact-generated anomalies
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DOI：
10.1016/j.icarus.2020.114176
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发表时间：
2020-03
期刊：
影响因子：
3.2
通讯作者：
T. Ruedas;D. Breuer
中科院分区：
文献类型：
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作者：
T. Ruedas;D. Breuer
我们从受盆地形成陨石撞击影响的火星地幔对流模型的结果中推导出合成电导率、地震速度和密度分布。电导率在强烈耗尽的最顶部地幔中具有中间最小值，夹在下地壳的较高电导率和在深度大于400公里处向几乎恒定的高值平稳增加之间。体声速在整个地幔中基本上平稳地增加，只有在1100 km深度附近出现β-橄榄石时有一个明显的变化。对撞击的地下痕迹的可探测性进行的评估表明，至少如果从冲击熔化的目标中有效地提取熔化物，那么撞击的特征在两个观测点中都是可见的，但即使对于大型盆地，它也不总是特别明显;具有广泛的空间和时间覆盖范围的观测将提高其可探测性。电磁测深可能提供另一种可能性来研究地幔的性质，特别是在撞击结构的区域。与地震学和重力测量学相比，它在火星内部的应用迄今为止还没有得到多少考虑。特别令人感兴趣的是它限制地幔含水量的潜力。通过将撞击结构的电磁探测数据与模型预测进行比较，也有可能回答撞击产生的熔体的提取效率这一悬而未决的问题。
We derive synthetic electrical conductivity, seismic velocity, and density distributions from the results of martian mantle convection models affected by basin-forming meteorite impacts. The electrical conductivity features an intermediate minimum in the strongly depleted topmost mantle, sandwiched between higher conductivities in the lower crust and a smooth increase toward almost constant high values at depths greater than 400 km. The bulk sound speed increases mostly smoothly throughout the mantle, with only one marked change at the appearance of β-olivine near 1100 km depth. An assessment of the detectability of the subsurface traces of an impact suggests that its signature would be visible in both observables at least if efficient melt extraction from the shock-molten target occurs, but it will not always be particularly conspicuous even for large basins; observations with extensive spatial and temporal coverage would improve their detectability. Electromagnetic sounding may offer another possibility to investigate the properties of the mantle, especially in regions of impact structures. In comparison with seismology and gravimetry, its application to the martian interior has received little consideration so far. Of particular interest is its potential for constraining the water content of the mantle. By comparing electromagnetic sounding data of an impact structure with model predictions, it might also be possible to answer the open question of the efficiency of extraction of impact-generated melt.