Modelling of Greenland’s Lithospheric Structure with Gravity Gradients

Abstract:

The geothermal heat-flux is dependent on the lithospheric structure. However, the lithospheric structure of Greenland remains poorly known due to its ice coverage, the sparseness of seismological stations and the limitation of geological outcrops to coastal areas. Previous studies, based on various geophysical methods, generate partly contradicting results for Moho and LAB depth.

In this study, which is part of the ESA STSE 3D Earth, we build a lithospheric model for Greenland by inverse and forward modelling of satellite gravity gradients. We present a first-order lithospheric background model, which incorporates seismological and petrological information, as well as geological data in order to distinguish different tectonic domains. The model is adjusted to fit the gravity gradients as well as the isostatic topography.

We use an update of the seismic tomography model SL2013 to calculate a tectonic regionalisation with k-means clustering. In an inversion for the Moho depth with gravity gradient data this regionalisation is used to allow a laterally variable density contrast, based on the different tectonic regions.