North Atlantic

The eastern part of the North Atlantic has been used as a case example in the STSE GOCE+
GeoExplore (e.g. Ebbing et al. 2013, Bouman et al. 2015) and is as well studied in the STSE Swarm+
Slim. In this project we will extend the study area to cover the entire North Atlantic. Recent
compilations of potential field data and derived crustal thickness from seismic and gravity data, and
upper mantle seismic velocity models will be merged with other existent data and models for
constructing a comprehensive crust, lithosphere and upper mantle North Atlantic model(see Table 2)
One of our goals is to validate the origin of the upper mantle velocity anomaly and to link this structure
to the evolution of the North Atlantic. The range of possible scenarios will make pure forward model
a tedious task. For example, a recent S-wave velocity model of the North Atlantic region links slow
velocities of Southern Norway to the Mid-Atlantic (Rickers et al. 2013). However, based on almost the
same set of seismological stations, an alternative S-wave velocity upper mantle model for Europe does
not detect the anomaly beneath Southern Norway (Legendre et al. 2012). Additional seismological
models exist (e.g. Bijward & Spakman, 1999, Weidle and Maupin, 2008) and they will be evaluated
here and tested against the satellite gravity gradients.
An interesting addition is the link of the tomography models with magnetic field analysis. For example,
Li et al. (2013) presented an analysis of the thermal structure for the North Atlantic region based on a
global magnetic field model. The general trend of their results agrees with models for the cooling of
the oceanic lithosphere and they observed a correlation of the Curie isotherm with crustal thickness
estimates. In some areas, the analysis seems to indicate upper mantle sources, which they interpreted
as indications of mantle convection. Li et al. (2013) used magnetic data from a global model
representation close to the surface (where locally shallow sources might dominate), and that makes
it difficult to detect subtle anomalies from deep sources, as the decline of magnetization with depth
is subtle compared to the changes in remanent magnetization between crustal blocks within the
oceanic plate. This clearly illustrates the necessity of an integrated approach to improve upper mantle
imaging and to address some of the long-standing questions with respect to the thermal history of the
North Atlantic.