HYPO-TZ - Generation and assessment of hypothetical seismic mantle transition zone structures

Basic data for this project

Description

The mantle transition zone (TZ), typically defined as the region from roughly 410 to around 660 km depth, marks the boundary between upper and lower mantle. It is characterised by a highly complex mineralogy, but no consensus has been reached yet regarding its influence on global mantle circulation. The complex behaviour of the mineral phase assemblage as a function of pressure (P) and temperature (T) likely impacts the vertical mass and heat flow through the TZ due to variations in buoyancy and latent heat effects as well as the potentially associated variations in rheological parameters. Despite numerous studies in seismology and geodynamics in the last decades, no clear and consistent picture of the transition zone and its influence on mantle flow has emerged yet. In this project, we aim at providing new insight into TZ structure and dynamics based on a novel multi-disciplinary theoretical forward-modelling approach together with comparisons of the hypothetical scenarios with seismic observations. Our study will include simulations coupling mantle circulation models, thermodynamic models of mantle mineralogy and 3-D global seismic wave propagation as well as automated processing of synthetic and observed seismic data. This approach will enable us to gain new insight into the relation between geodynamic input parameters and the seismic "signature" of the transition zone.