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.

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“…The optimum upward continuation height is obtained by the maximum cross correlation between the upward continued fields at the successive heights which presents a maximum deflection. More details concerning the steps of data treatment are found in [41] [42] [43] and references therein.…”

“…The selection criterion of the regional field is the more objective, as it is based on the correlation between the regional analytical and the regional spectral. This correlation also determines the depth of investigation and takes into account the variations of Bouguer anomalies in all the directions [41] [42]. Indeed, to derive an optimum upward continuation height h 0 for gravity separation, the empirical method of [41] was used.…”

“…This correlation also determines the depth of investigation and takes into account the variations of Bouguer anomalies in all the directions [41] [42]. Indeed, to derive an optimum upward continuation height h 0 for gravity separation, the empirical method of [41] was used. The upward continuation is a method used to separate a regional gravity anomaly resulting from deep sources from the observed gravity [41].…”

“…Indeed, to derive an optimum upward continuation height h 0 for gravity separation, the empirical method of [41] was used. The upward continuation is a method used to separate a regional gravity anomaly resulting from deep sources from the observed gravity [41]. The optimum upward continuation height is obtained by the maximum cross correlation between the upward continued fields at the successive heights which presents a maximum deflection.…”

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“…Indeed, [23] proposed a method of determining the optimal height for the upward continuation of the gravimetric field h 0 . It consists of determining the altitude of the upward continuation of the Bouguer where the curve of correlation between the extended fields of the successive altitudes shows a maximum deflection.…”