The European Alps and nearby orogenic belts sensed by GOCE

The Alpine arc and surrounding area is ideal to demonstrate the great achievements of satellite GOCE in producing a transnational - trans-orogenic and homogeneous gravity field. Three mountain ranges meet here, the Alps, the Dinarides, and the Appennines, and there being the continent-ocean transition to the Provençal and Ionian basins. The gravity observations of GOCE produce an unparalleled global field that allows to detect geological features and classify types of continental crust. We demonstrate that GOCE is superior to existing global fields based on terrestrial data, as is EGM08, by showing the regional variability of the root mean square difference between the two fields. The difference is governed by the quality of the terrestrial field, the satellite field having homogeneous error. We then investigate the gravity anomaly and Bouguer field of GOCE and residual fields based on a regression between topography and gravity. The amplitude range of the residual Bouguer field is reduced by 48%, the root mean square amplitude variation by 56%, demonstrating that the regression efficiently eliminates the isostatic field. As expected, for the gravity anomaly the reduction is less and amounts to 21% in amplitude range and 20% in root mean square amplitude. The residual fields highlight geological units, as deep sedimentary basins (Po-basin sediments, Alpine foreland basin), the Ivrea body and the Periadriatic intrusions, and the gravity high centered on the Tuscan archipelagos connecting western Corsica and the Tuscan mainland, to which the Larderello thermal fields also belong. The transition of the eastern margin of the Alpine arc towards the Pannonian basin is marked by two subparallel N-S striking positive anomalies separated by a negative linear anomaly, that reach the eastern limit of the Tauern window and southwards reach the Dinarides. The observation of these anomalies is new and shows the strength of GOCE in mapping the field homogeneously crossing geologic, orographic and national boundaries.