Periodic Reporting for period 2 - TimeMan (RHEOLOGY OF EARTH MATERIALS: CLOSING THE GAP BETWEEN TIMESCALES IN THE LABORATORY AND IN THE MANTLE)
Okres sprawozdawczy: 2020-09-01 do 2022-02-28
Laboratory experiments can now reach the high-pressure, high-temperature conditions of the interior of the Earth, but they are much faster. The laws determined from these experiments performed at human timescales must be extrapolated to Earth’s conditions over several orders of magnitude. This leads to highly questionable results as demonstrated by recent comparison with surface geophysical observables.
Strain rates couple space and time. We cannot expand time, but we can now reduce length scales. By using the new generation of nanomechanical testing machines in transmission electron microscopes, we can have access to elementary deformation mechanisms and, more importantly, we can measure the key physical parameters which control their dynamics. At this scale, we can have access to very slow mechanisms which were previously out of reach. This approach can be complemented by numerical modelling. By using the recent developments in modelling the so-called “rare events”, we will be able to model mechanisms in the same timescales as nanomechanical testing.
Applied to olivine, the main constituent of the upper mantle, this will provide the first robust, physics-based rheological laws for the lithospheric and asthenospheric mantle to be compared with surface observables and incorporated in geophysical convection models.