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Abstract:
This study aims to find evidence of a residual thermal anomaly along the path of a hotspot beneath the continental lithosphere using gradiometry data.Considering a simple model of thermal anomaly, we calculated the associated gravity gradients and found that the horizontal component which is highly sensitive to the directional structure of the source has a magnitude of several hundred mEötvös, well above the current detection level of the data.Using GOCE satellite data, we created scale-orientation diagrams in four regions (Africa, Greenland, Australia, and Europe) to determine the direction and spatial scale of the strongest signal. We searched for a signal in the direction of plate movement, with a spatial scale of a few hundred kilometers (scale of the plumes). We then determined the ancient positions of the hotspots over the lithosphere and created maps of Bouguer gravity gradients and topographic gradients, filtered at a spatial scale of a few hundred kilometers and oriented in the direction of the hotspot's path. Interpreting these signals is challenging as it is difficult to separate the residual thermal anomaly from the surface topography and related crustal root , if the topography is aligned with the direction of plate motion and/or correlated with the volcanic chains generated by the plume. Despite these challenges, the results shows that gradiometry data has the potential to track hotspots in the continental lithosphere for tens of millions years.
