Iterative 2D Gravity Modelling for Basement Depth Estimation

Abstract

In gravity modelling, iterative refinement of 2D basement geometry is a classical problem where the density contrast has to be determined in advance. We present a relatively simple method to estimate 2D basement depth along with its density contrast. Known basement depths at several points and their associated gravity anomalies determine the gravity - depth relationship that is used to obtain the first estimate of the overall basement depth. The initial model response is calculated with a unitary density. The linear regression between calculated model response and actual gravity data results in the density contrast estimation. The misfit or residuals and the gravity - depth relationship are used to update the model iteratively. The proposed technique is relatively stable and results in a recovered model quite similar to the synthetic model. We also explore the possibility to include estimation of the constant the regional anomaly.