Sensitivity analysis of gravity gradient inversion of the Moho depth—a case example for the Amazonian Craton
Sensitivity analysis of gravity gradient inversion of the Moho depth—a case example for the Amazonian Craton
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DOI：
10.1093/gji/ggaa122
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发表时间：
2020-06
影响因子：
2.8
通讯作者：
P. Haas;J. Ebbing;W. Szwillus
中科院分区：
文献类型：
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作者：
P. Haas;J. Ebbing;W. Szwillus
我们提出了一种新的方法，线性重力反演估计莫霍面深度，它允许使用任何重力分量，而不是垂直重力分量。用高斯-牛顿法求解反问题，用镶嵌面法计算起伏莫霍面的重力场。据此，利用地震区划信息，可以实现密度对比度的横向变化。我们的方法说明了一个合成的例子，我们用它来探索不同的正则化参数。垂直重力梯度gzz提供了具有适当参数的最合理的结果。作为一个例子，我们反演的莫霍面深度的亚马逊河流域及其周围地区。结果受到主动地震测量估计的限制。我们的新莫霍面深度模型与构造域相关，并与以前的模型一致。估计的密度对比的构造域同意与岩石圈结构，并显示与300-450公斤m-3的低密度对比的大陆域，而海洋揭示了450-500公斤m-3的密度对比。估计的大陆密度对比范围更广，反映了前寒武纪褶皱带的不确定性，这是由其小的重力信号引起的。我们的研究结果表明，在莫霍面深度的变密度对比是一个有价值的增强重力反演。
We present a novel approach for linearized gravity inversion to estimate the Moho depth, which allows the use of any gravitational component instead of the vertical gravity component only. The inverse problem is solved with the Gauss–Newton algorithm and the gravitational field of the undulating Moho depth is calculated with tesseroids. Hereby, the density contrast can be laterally variable by using information from seismological regionalization. Our approach is illustrated with a synthetic example, which we use to explore different regularization parameters. The vertical gravity gradient gzz provides the most reasonable results with appropriate parameters. As a case example, we invert for the Moho depth of the Amazonian Craton and its surroundings. The results are constrained by estimates from active seismic measurements. Our new Moho depth model correlates to tectonic domains and is in agreement with previous models. The estimated density contrasts of the tectonic domains agree well with the lithospheric architecture and show with 300–450 kg m–3 lower density contrasts for continental domains, whereas the oceans reveal a density contrast of 450–500 kg m–3. The wider range of estimated density contrast for the continent reflects uncertainties in Precambrian Fold Belts that arise from its small gravity signal. Our results demonstrate that a variable density contrast at the Moho depth is a valuable enhancement for gravity inversion.