An algorithm to calculate the gravity anomaly of sedimentary basins with exponential density‐depth relationships

Abstract

A B S T R A C TWe derive wavenumber domain expressions to calculate the gravity anomaly of a body with irregular bounding surfaces and an exponential density-depth relationship. We apply the method to sedimentary basins, which commonly have this type of geometry and density distribution. The mathematical formulation also allows the exponential density-depth relationship to be measured from an arbitrary irregular surface rather than the top surface. Using this arrangement, the gravity anomaly of exhumed sedimentary basins can be predicted if the amount of eroded section can be estimated. The corresponding inverse algorithms are also derived. Examples of the use of the forward algorithms, from the Galicia Interior Basin and the Central Irish Sea Basin, are used to illustrate these methods.

Structure and evolution of the northern Barents-Kara Sea continental margin from integrated analysis of potential fields, bathymetry and sparse seismic data

“…By introducing a density-depth relationship in the forward and inverse gravity modelling of deep sedimentary basins, the reliability of solutions can be substantially improved (Granser 1987;Chappell & Kusznir 2008a). By introducing a density-depth relationship in the forward and inverse gravity modelling of deep sedimentary basins, the reliability of solutions can be substantially improved (Granser 1987;Chappell & Kusznir 2008a).…”

“…A density-depth relation based on well-log data from the Barents Sea region was published by Ebbing et al (2007) and . The gravity anomaly because of the sedimentary cover with an exponential density-depth function was computed using the method of Chappell & Kusznir (2008a). The gravity anomaly because of the sedimentary cover with an exponential density-depth function was computed using the method of Chappell & Kusznir (2008a).…”

“…This effect is significantly reduced using an exponential density-depth function in sediments for gravity modelling (Granser 1987;Chappell & Kusznir 2008a) because sharp density jump at the top crystalline basement can be avoided. Incorrectly interpreted top basement may give a bias in the Moho geometry obtained from the gravity inversion.…”

“…We apply the method of Chappell & Kusznir (2008b) for inversion of the mantle residual gravity anomaly (MRA) and complement this with estimation of the gravity effect of sedimentary cover using an exponential density-depth function (Granser 1987;Chappell & Kusznir 2008a). We apply the method of Chappell & Kusznir (2008b) for inversion of the mantle residual gravity anomaly (MRA) and complement this with estimation of the gravity effect of sedimentary cover using an exponential density-depth function (Granser 1987;Chappell & Kusznir 2008a).…”

3D gravity interface inversion constrained by a few points and its GPU acceleration

“…The other is the variable density-contrast model, which is the density contrast of sedimentary changes with depth and/or horizontal position partly as a result of compaction. The variable density-contrast models include exponential decay model (Cordell, 1973;Chai and Hinze, 1988;Litinsky, 1989;Chappell and Kusznir, 2008), hyperbolic decay model (Litinsky, 1989;Silva et al, 2006;Rao and Pramanik et al, 1994), linear model (Murthy and Rao, 1979;Pokanka,1998;Hansen, 1999;Holstein, 2003), quadratic model (Rao, 1986;Rao et al,1990;Garcia-Abdeslem et al, 2005), parabolic model Sundararajan, 2004), polynomial model( Guspi,1990;Zhang et al, 2001). However, inclusion of variable density contrast in the interface inversion obviously introduces substantial complication in gravity modelling, thus inevitably increasing the computational burden.…”