Joint inversion of gravity and magnetic data for two-layer models

Abstract

Gravity and magnetic data are inverted jointly in terms of a model consisting of an interface separating two layers having a constant density and magnetization contrast. A damped least-squares inversion is used to determine the topography of the interface. The inversion requires knowledge of the physical property contrasts across the interface and its average depth. Since the relationship between model parameters and data is weakly nonlinear, a constant damped least-squares inverse is used during the iterative solution search. The effect of this inverse is closely related to a downward continuation of the field to the average interface depth. The method is used to map the base of the Sept-Iles mafic intrusion, Quebec, Canada, and the shape of the central uplift at the Chicxulub impact crater, Yucatan, Mexico. At Sept-Iles, the intrusion reaches a thickness of [Formula: see text], coincident with the maximum gravity anomaly, south of the intrusion center. At Chicxulub, the top of the central uplift is modeled to be [Formula: see text] deep and has a single peak form.

Joint inversion of gravity and magnetic data for a two-layer model

“…Gallardo-Delgado et al (2003) extended the 3D approach to include a continuous density variation with depth and the magnetization direction as unknown parameters. A damped least-squares method was used for joint inversion of gravity and magnetic data by Pilkington (2006) to determine the topography of an interface having a constant density and magnetization contrast. Wu et al (2007) proposed a joint gravity and magnetic inversion of a variable density interface which better matches with actual geologic conditions.…”

Magnetic Basement Depth Inversion in the Space Domain

“…Most of the inversion methods that successfully tackle this problem are based on PARKER's (1973) forward method to rapidly compute the magnetic effect of an arbitrary interface separating two homogeneous media. PARKER's (1973) formula sets a relationship between the Fourier transform of the magnetic data (the vector h) and the sum of the Fourier transforms of the powers of the vector p describing the topography at discrete points (PILKINGTON, 2006):…”

“…Vector K is constructed from wavevector k as K = (ik x , ik y , |k|) and, j and t are the direction cosines of the source magnetization and geomagnetic field, respectively. Examples of successful inversion of magnetic data based on PARKER's (1973) formula are given in PILKINGTON and CROSSLEY (1986), PILKINGTON (2006), andCARATORI TONTINI et al (2008). The major advantage of these inversion methods is the rapid computation of magnetic response, and its major restriction is that the average depth of the interface [variable z o in equation (2)] must be known.…”

Joint Application of Concentration and δ18O to Investigate the Global Atmospheric CO Budget

“…The impact of the different units should be correctly accounted for the inversion [77]. Previous studies [24,26,33] have solved the inverse problems through minimizing the model-observation difference without balancing the two properties.…”

“…One of the methods to balance the contribution of two data sets is sequential use of each observation, where the solution inverts one measurement data set first and the result provides the input for the inversion of the second observational information [77,80].…”