Plate motion and mantle plumes in thermal and themochemical convection

• Applicant: Professor Dr. Ulrich Hansen
• Subject Area: Geophysics
• Term: from 2012 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 219008056

Plate motion represents the surface expression of the mantle convection. Numerically it is studied by applying a complex rheological approach. We have already developed different modelling methods in order to study plate motion and its feedback on mantle convection. The aim of this proposal is to investigate plate reversals. These are considered as a possible mechanism for the bend in the Hawaiian emperor chain and shall be compared to the other mechanism (tilt of a plume as a cause of the mantle convection). We have already observed both mechanisms in our models. However, the conditions leading to plate reversals or a plume tilt in self-consistent mantle convection models are not clear. Furthermore, the frequency and strength of changes in the plate direction have to compared to the observations on Earth. Can a strong kink, as observed for the Hawaiian emperor chain, be explained by a tilting plume? Or does this cause a rapidly changing surface motion? Is it possible to anchor a plume, so that only occasional tilts are observed, by applying chemical dense material at the core-mantle boundary or a specific rheology?

• DFG Programme: Research Grants