Reconstructing 200 Ma of Lithosphere Subduction, Friday!
Our Distinguished Speaker this week is Dr. John Suppe, University of Houston. His presents "The Second Half of Plate Tectonics: Finding the Last 200 Ma of Subducted Lithoshpere and Incorporating It into Plate Reconstruction".
Precise plate-tectonic reconstruction of the Earth has been constrained largely by the seafloor magnetic-anomaly record of the present oceans formed during the dispersal of the last supercontinent since ~200Ma. The corresponding world that was lost to subduction, which accounts for ~100% of the surface area of the Earth, has been only sketchily known. We have developed methodologies to map in 3D these subducted slabs of lithosphere in seismic tomography and to unfold them to the Earth surface, using them to constrain plate tectonic reconstructions. Slab edges are commonly formed at times of plate reorganization (for example bottom edges typically record initiation of subduction) such that unfolded slabs fit together in picture-puzzle fashion at times of reorganization, analogous to the fitting together of Africa and South America. Mapping to date suggests that a relatively complete and decipherable record of lithosphere subducted over the last ~200Ma exists in the mantle today, providing a storehouse for new discoveries.
Come see plate tectonics from new perspective, Friday, February 2, 2018 at 12:30 PM, Room 204, Natural Science Building on the East Lansing campus.