IGPP is pleased to invite you to join its Fall 2021 Seminar Series presentation featuring MIT's Matej Peč. Dr. Peč's talk, "Reactive Melt Migration in Partially Molten Rocks" will be available via Zoom on Tuesday, October 26, 2021, starting at 12:00pm. Zoom: https://ucsd.zoom.us/j/91853961010?pwd=VGo0UklLMjhEMjlNMzN3N0RiUWFGQT09. Password: melt
Date: Tuesday, October 26 2021
Time: 12:00 pm, Pacific Time
Note: This meeting will be recorded. Please make sure that you are comfortable with this before registering.
Abstract: Melting along spreading centers and subduction zones is a fundamental manifestation of plate tectonics. In these settings, melt migrates toward Earth’s surface due to buoyancy, resulting in much of the chemical exchange between crust, mantle, and atmosphere. Several lines of evidence imply that, at some stage from melting to eruption, melt must segregate into high permeability channels with extraction isolated enough to preserve chemical disequilibrium and quick enough to preserve radiogenic disequilibrium. Current knowledge suggests that high-permeability channels in the asthenosphere may emerge as a consequence of several interacting instabilities in porous, deformable, fusible two-phase media.
In the laboratory, significant progress in characterizing stress-driven melt segregation has been achieved over the last ~20 years, motivating new developments in the theory of melt migration. The conditions necessary for melt channelization due to melt-rock reactions, known collectively as reaction-infiltration instabilities (RIIs), have been explored extensively through theoretical models. However, experimental studies on reaction-driven melt channelization in mantle rocks at high pressures and temperatures were lacking due to technical challenges. In this talk, I present the results from a suite of experiments designed to investigate the formation and propagation of RIIs in an olivine – pyroxene – basalt system and then compare the experimental results to observations on natural formations. The results provide first-order constraints for theoretical models that link RIIs and melt migration in the upper mantle.