Mapping the depth to basement from gravity anomalies is an essential geophysical survey in sedimentary basins. We propose an iterative method to simultaneously estimate the basement relief, exponential density-depth model, and constant offset. The iterative process is achieved by applying the approximate invariance, which directly relates the basement depth to density parameters and constant offset. The method can be employed provided that there are a few known depth constraints. By testing the sediment and basement models, we find that the observation plane height and random noise of gravity anomalies have almost no impact on the stability of the method. However, the method is slightly affected by the number of constraints and is sensitive to the uncertainty of constraint depth. Finally, we successfully use the new method to map the depth to basement in the Pannonian basin using several depth constraints from drilling data and obtain the almost same density-depth model as that assumed based on drilling density. The method can be extended to recover the discontinuous basement relief and estimate other density-depth models, such as polynomial density function, once appropriate adjustments are made to the method.

中文翻译：

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指数近似不变性：从重力异常映射到地下室的深度


根据重力异常绘制基底深度是沉积盆地中一项重要的地球物理调查。我们提出了一种迭代方法来同时估计基底起伏、指数密度深度模型和常数偏移量。迭代过程是通过应用近似不变性来实现的，该近似不变性将基底深度与密度参数和常数偏移直接相关。如果存在一些已知的深度约束，则可以采用该方法。通过对沉积物和基底模型的测试，我们发现观测面高度和重力异常的随机噪声对方法的稳定性几乎没有影响。但该方法受约束数量影响较小，且对约束深度的不确定性敏感。最后，我们成功地使用新方法利用钻井数据的几个深度约束来绘制潘诺尼亚盆地基底的深度，并获得了与基于钻井密度假设的几乎相同的密度-深度模型。一旦对该方法进行适当调整，该方法可以扩展以恢复不连续的基底起伏并估计其他密度深度模型，例如多项式密度函数。