Modelling of density interface with binomial density variation

Abstract

The concept of variable density plays an important role in interpreting the gravity anomalies of sedimentary basins and in obtaining the real basement depth values. A second-order binomial density function has been introduced to model the rapid density variation of sedimentary rocks with depth. A recursive analytical expression for the gravity anomaly of an out-cropping two-dimensional vertical prism is then derived. Based on the expression, a computer-based algorithm is developed to solve the structure of the sedimentary basin from its gravity anomalies. The sedimentary strata above the density interface are approximated by a series of juxtaposed prisms and their thicknesses are adjusted accordingly until the theoretical anomalies fit the observed anomalies. The first term of the binomial density function is used in the Bouguer slab formula to obtain the initial depth estimates of the basin. The gravity anomaly profile of the Godavari basin, India, where the density of sedimentary rocks is found to vary with depth, is interpreted. © 1995.