A model study for estimating optimum upward-continuation height for gravity separation with application to a Bouguer gravity anomaly over a mineral deposit, Jilin province, northeast China

Abstract

Upward continuation can be used to separate a regional gravity anomaly resulting from deep sources from the observed gravity. We present a practical method, based on model studies, to derive an optimum upward continuation height for regional-residual gravity separation. Using this method we can calculate an optimal height for upward continuation. Although mathematically there is no optimum height, this method provides an objective procedure to calculate a best height for upward continuation. We initially use a 2D model to calculate an optimum separation height, as given by the maximum crosscorrelation between the upward continuation of the observed gravity and a known regional anomaly. For an unknown regional field, we calculate a series of crosscorrelations between the upward continuations at two successive heights. The average height of the maximum deflection of these crosscorrelation values yields the optimum height for regional-residual separation. The method was applied to the Bouguer gravity anomaly over a mineral deposit in the Jilin province in northeast China. When we subtract the estimated regional anomaly obtained in this manner from the Bouguer anomaly, we can obtain a residual anomaly that clearly shows the location of two known iron bodies.