The Use of GOCE Data for Detection and Classification of Mantle Plumes

Conned hot upwelling of material in the Earth’s mantle is known as a mantle plume. Plumes are believed to origin from the core-mantle thermal boundary layer and rise through the entire mantle driven by positive buoyancy forces. The gravity signal caused by such a mantle plume is given by the superposition of the effect of the hot anomaly itself and the effects of the upward deected surface and internal phase boundaries. The strength and spectrum of the gravity signal depends on the position of the plume in the Earth’s mantle, as well as on its temperature, size, and rise velocity, and on the mantle viscosity. With the use of numerical uid dynamic modeling the gravity eld of a typical mantle plume is studied for various stages of rise. The maximum gravity signal is on the order of 60 mgal and is found when the top of the plume reaches the base of the lithosphere. The gravity anomaly spectrum of a mantle plume, while rising through the mantle is signicantly different from the gravity spectrum of an old plume, which is spreading below the lithosphere. While the gravity eld of deep mantle plumes is mainly characterized by long wavelength signals, plumes encountering the lithosphere base and in an old stage of spreading exhibit considerable energy in a shorter wavelength band related to the size of the plume head. Furthermore the contribution of mantle plumes to the global gravity potential eld is estimated by projecting the numerical plume on 41 known hot spot locations in the Earth’s mantle and convolving the density eld with the response function of the viscous mantle. Finally the possibility to use GOCE to classify known plumes and to detect plumes rising through the mantle is discussed.