Propagating rifts
Channel: Paul Wessel
Date: 2020-02-05

Dr. Richard Hey (University of Hawaii at Manoa) gave a guest lecture via Skype in Fall 2008 for a graduate class on Advanced Plate Tectonics in SOEST, University of Hawaii at Manoa.  The students recorded the lecture and produced video podcasts of the event.  This is one of 8 such lectures from the course which was taught by Prof. Paul Wessel.

ABSTRACT:

"Propagating rifts are extensional plate boundaries that gradually break through lithospheric plates, forming new plate boundaries and rearranging the geometries of old ones. They occur on scales ranging from overlapping spreading centers to microplates to continental breakup. The combination of seafloor spreading and propagation produces a characteristic V-shaped wedge of lithosphere, with progressively younger and longer isochrons abutting the “pseudofaults” that bound this wedge. For continental rifting, the pseudofaults are the continental margins.  Oceanic propagators that replace preexisting spreading centers cause ridge jumps and lithospheric transfer from one plate to another. This changes the classic plate tectonic geometry, producing structures oblique to ridges and transforms, and results in asymmetric accretion of lithosphere to the plates. Rift propagation is the primary mechanism by which Earth’s accretionary plate boundary geometry is reorganized."