High-resolution investigation of upper mantle discontinuities

• Applicant: Professorin Dr. Christine Thomas
• Subject Area: Geophysics
• Term: from 2010 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 166864316

The structure of the seismic discontinuities of the mantle transition zone between 410 and 660 km depth in different tectonic settings provides important constraints on the thermal, chemical and dynamical state of the Earth’s mantle. We aim to study the upper mantle discontinuities, which are formed by solid-solid phase transitions of the mantle material, using high-resolution seismic array analysis methods and mineral physics experiments to investigate their fine-scale structure and local variations in different dynamic regimes. The use of array seismology will improve lateral and vertical resolution of the seismic structures. In particular we aim to resolve controversial issues about sharpness (i.e. vertical thickness) of the upper mantle discontinuities: the interpretation of these results in terms of pressuretemperature interval and kinetics of mineral phase transitions can yield important constraints on geodynamical models of mantle convection. The second issue that we aim to address is the depth of the 410 km discontinuity in different tectonic settings which, from the pressuretemperature slope of the phase transition, can be interpreted in terms of lateral temperature heterogeneities. Related to this, we intend to search for reflections associated with phase transitions from other minor constituents of the mantle, which are more sensitive to chemistry.

• DFG Programme: Research Grants