Depth-dependent density change within the continental upper mantle

Abstract

Abstract:The empirical model of the depth-dependent density change within the upper continental mantle is derived in this study. The density of the upper(most) mantle underlying the continental crust is obtained from the estimated values of the crust-mantle (Moho) density contrast. Since the continental crustal thickness varies significantly, these upper mantle density values to a large extent reflect the density changes with depth. The estimation of the Moho density contrast is done through solving Moritz's generalization of the Vening-Meinesz inverse problem of isostasy. The solution combines gravity and seismic data in the least-squares estimation model. The estimated upper mantle density (beneath the continental crust) varies between 2770 and 3649 kg/m 3 . The upper mantle density increases almost proportionally with depth at a rate of 13 ± 2 kg/m 3 per 1 km at the investigated depth interval from 6 to 58 km.

Moment of inertia for rock blocks subject to bookshelf faulting with geologically plausible density distributions

“…However, the reverse can also happen (Ebbing et al 2007 and its review) with depth, especially if evaporitic rocks are involved (Romer and Neugebauer 1991). An average density gradient can be 0.32 Mg m −3 km −1 (Carlson and Herrick 1990), or 13 ± 2 kg m −3 km −1 (Tenzer et al 2012). Metamorphism can induce gradual density gradients in any orientation in some cases (Zhou 2009).…”

Inverse problem for the gravimetric modeling of the crust-mantle density contrast

“…Sjöberg and Bagherbandi (2011) applied the least-square method to simultaneously estimate the Moho depth and density contrast globally using the gravimetric and seismic models. Tenzer et al (2012aTenzer et al ( , 2012b used to same method to determine the Moho density contrast under oceans and continents.…”