Gravimetric recovery of the Moho geometry based on a generalized compensation model

Abstract

Gravity data used for a recovery of the Moho depths should (optimally) comprise
only the gravitational signal of the Moho geometry. This theoretical assumption
is typically not required in classical isostatic models, which are applied in gravimetric
inverse methods for a recovery of the Moho interface. To overcome this theoretical deficiency,
we formulate the gravimetric inverse problem for the consolidated crust-stripped
gravity disturbances, which have (theoretically) a maximum correlation with the Moho
geometry, while the gravitational contributions of anomalous density structures within
the lithosphere and sub-lithosphere mantle (including the core-mantle boundary) should
be subtracted from these gravity data. In the absence of a reliable 3-D Earth’s density
model, our definitions are limited to the crustal and upper mantle density structures. The
gravimetric forward modeling technique is applied to compute these gravity data using
available models of major known anomalous crustal and upper mantle density structures.
The gravimetric inverse problem is defined by means of the (non-linear) Fredholm integral
equation of the first kind. After linearization of the integral equation, the solution to the
gravimetric inverse problem is given in a frequency domain. The inverse problem is formulated
for a generalized crustal compensation model. It implies that the compensation
equilibrium is (theoretically) attained by both, the variable depth and density of compensation.
A theoretical definition of this generalized crustal compensation model and a
formulation of the gravimetric inverse problem for finding the Moho depths are given in
this study.