AuthorsS. Clark, D. Stegman and D. R. Müller
TitleEpisodicity in Back-Arc Tectonic Regimes
AfilliationScientific Computing, , Scientific Computing
Project(s)Center for Biomedical Computing (SFF)
Publication TypeJournal Article
Year of Publication2008
JournalPhysics of the Earth and Planetary Interiors
NumberSpecial Issue on Recent Advanced in Computational Geodynamics: Theory, Numerics and Applications
Date PublishedNovember

The evolution of back-arc basins is tied to the development of the dynamics of the subduction system they are a part of. We present a study of back-arc basins and model their development by implementing 3-D time-dependant computer models of subduction including an overriding plate. We define three types of episodicity - pseudo-, quasi- and hyper-episodicity, and find evidence of these in nature. Quasi-episodicity, in which the back-arc shifts between phases of rifting/spreading and quiescence, is the dominant form of episodic back-arc development in the present. We find this type of episodicity in models for which the system is dynamically consistent - that we have allowed the subducting plate's velocity to be determined by the sinking slabs' buoyancy. Hyper-episodicity occurs in models that are driven by an imposed velocity boundary condition. In this case the full range of behaviour is witnessed - trench advance, retreat and stability. In nature, this occurs rarely, but may occur in places that undergo sudden shifts in plate tectonics and that are therefore unable to self-balance within a noticeable period. Pseudo-episodicity is a category for back-arc rifting or spreading that seems to be periodic, but is really related to ridge-jumps and the brittle nature of the overriding plate. Constant rollback and pseudo-episodic back-arc rifting are witnessed in places where the subducting plate's motion is inhibited by a retarding force, at the trailing edge in our models. This may be, for example, a continent or another subduction zone. Records of back-arc basin rifting/spreading and quiescence from oceanic paleo-age grids have been observed and further validate the conceptual division of epsidocity into these three categories.

Citation KeySimula.SC.91