Since marine seismic studies are relatively sparse and unevenly distributed, detailed tomographic images of the Moho geometry under large parts of the world’s oceans and marginal seas are not yet available. Marine gravity data is, therefore, often used to detect the Moho depth in these regions. Alternatively, Airy’s isostatic theory can be applied for this purpose. In this study, we compare different isostatic and gravimetric methods for a Moho recovery under the oceanic crust and continental margins, particularly focusing on a numerical performance of Airy, Vening Meinesz–Moritz (VMM), direct gravity inversion, and generalized (for the Earth’s spherical approximation) Parker–Oldenburg methods. Numerical experiments are conducted to estimate the Moho depth beneath the Indian Ocean. Results reveal that, among these investigated methods, the VMM model is probably the most suitable for a gravimetric Moho recovery beneath the oceanic crust and continental margins, when taking into consideration the lithospheric mantle density information. This method could to some extent model realistically a Moho geometry beneath mid-oceanic spreading ridges, oceanic subductions, most of oceanic volcanic formations, and marine sediment deposits. Nonetheless, this model still cannot fully reproduce a gradual Moho deepening caused by a conductive cooling and a subsequent isostatic rebalance of the oceanic lithosphere, which can functionally be described by a Moho deepening with the increasing ocean-floor age. Results also indicate that the Airy method typically overestimates the Moho depth under oceanic volcanic formations, while the direct gravity inversion and generalized Parker–Oldenburg methods could not reproduce more detailed features in the Moho geometry. Since Pratt’s theory better describes a large-scale isostatic mechanism of the oceanic lithosphere by means of compensation density variations, but does not account for additional changes in compensation depth (i.e., Moho depth) that are caused by these density changes, we tested a possibility of combining Pratt and Airy’s isostatic theories in order to estimate the Moho depth under the oceanic crust. Even this combined model cannot fully reproduce a gradual Moho deepening with the increasing ocean-floor age.

由于海洋地震研究相对稀疏且分布不均，因此尚无法获得世界大部分海洋和边缘海下莫霍面几何的详细层析图像。因此，海洋重力数据通常用于检测这些区域的莫霍面深度。或者，艾里的均衡理论也可用于此目的。在这项研究中，我们比较了用于海洋地壳和大陆边缘下莫霍面恢复的不同等静压和重力测量方法，特别关注艾里、维宁迈因斯 - 莫里茨 (VMM)、直接重力反演和广义（对于地球的球近似）Parker-Oldenburg 方法。进行了数值实验以估计印度洋下的莫霍面深度。结果表明，在这些调查方法中，当考虑到岩石圈地幔密度信息时，VMM 模型可能最适合海洋地壳和大陆边缘下的重力莫霍面恢复。这种方法可以在某种程度上真实地模拟大洋中扩张脊、大洋俯冲、大部分大洋火山岩层和海洋沉积物下的莫霍面几何。尽管如此，该模型仍然不能完全再现由传导冷却和随后海洋岩石圈的均衡再平衡引起的逐渐莫霍面加深，这在功能上可以用随着海底年龄增加的莫霍面加深来描述。结果还表明，艾里方法通常高估了海洋火山地层下的莫霍面深度，而直接重力反演和广义 Parker-Oldenburg 方法无法再现 Moho 几何中更详细的特征。由于普拉特的理论通过补偿密度变化更好地描述了海洋岩石圈的大规模均衡机制，但没有考虑由这些密度变化引起的补偿深度（即莫霍面深度）的额外变化，我们测试了一种可能性结合普拉特和艾里的等静压理论来估计洋壳下的莫霍面深度。即使是这种组合模型也不能完全再现随着海底年龄的增加而逐渐加深的莫霍面。由于普拉特的理论通过补偿密度变化更好地描述了海洋岩石圈的大规模均衡机制，但没有考虑由这些密度变化引起的补偿深度（即莫霍面深度）的额外变化，我们测试了一种可能性结合普拉特和艾里的等静压理论来估计洋壳下的莫霍面深度。即使是这种组合模型也不能完全再现随着海底年龄的增加而逐渐加深的莫霍面。由于普拉特的理论通过补偿密度变化更好地描述了海洋岩石圈的大规模均衡机制，但没有考虑由这些密度变化引起的补偿深度（即莫霍面深度）的额外变化，我们测试了一种可能性结合普拉特和艾里的等静压理论来估计洋壳下的莫霍面深度。即使是这种组合模型也不能完全再现随着海底年龄的增加而逐渐加深的莫霍面。