Zoom Webinar ID#91682351231
On the Earth, plate tectonics and mantle convection is primarily driven by dense lithospheric slabs subducting into the mantle. The crustal slabs, made of the dense eclogite metamorphosed from the Mid-Ocean Ridge Basalt, provide one of the most important driving forces for slab subduction. The basaltic slab crust are also one of the major geochemical heterogeneities in the Earth’s interior. Locating these heterogeneities by comparing the experimentally determined seismic properties of eclogite with ambient mantle helps us to understand the Earth’s chemical evolution over geological time. I will present some of our recent experimental results on eclogite to reveal its seismic visibility in the Earth’s upper mantle. In addition, compared with the extremely active Earth, current-day Mars lacks ongoing tectonic activities such as volcanism, marsquakes with large magnitude (e.g. M>4.0) and mountain building process. We hypothesize that the mantle convection inside Mars can be hindered if the density contrast between Martian crustal slabs and the ambient Martian mantle is sufficiently different from Earth. I will present high pressure-temperature phase equilibrium experiments and calculations of an eclogite metamorphosed from a near-primitive Martian basalt. Our results indicate the crustal slab is less dense than the ambient Martian mantle down to the depth of ~630 km. Sustained subduction on Mars is difficult if the Martian crust is represented by the shergottic basalt. Our result may also help explain the stability of some high volcano edifices (e.g. the Olympus Mons) on Mars.