North America

The oldest blocks that form the North American continent are of Archean age. This cratonic core is sourrounded by accreted terrains of progressively younger age. It is a long standing question  how the oldest, coldest and hence densest blocks have maintained buoyancy (Mooney & Kaban 2010).

In this test example, we invert the USArray Magnetotelluric (MT) and seismic data together with gravity data in order to constrain the lithospheric structure in the North-Western USA. In order to invert surface wave data, new inversion codes will be developed. The global background model derived in 3D Earth will be used as a starting model. Ideal strategies for the joint inversion will be developed in individual inversions of the datasets. Challenges include the different resolution characteristics of the different models and the influence of topography. Furthermore the advantage of the homogenous data coverage of the gravity data in the case of sparse MT and seismic data will be investigated. The resulting density, resistivity and velocity models will help to image the lithospheric structure of the North-Western USA which is influenced by a variety of geological and tectonic processes (subduction, hotspot volcanism).

Flowcahrt of North America

Flowchart of the North America test example.