IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS017 Poster presentation 2390
Hydrothermal circulation within subducting crust: Implications for
subduction zone temperature
Mr. Troy Kummer
Glenn Spinelli
Hydrothermal circulation plays an important role in cooling and redistributing heat within highpermeability
ocean crust. We examine the effect of hydrothermal circulation on subduction zone
temperature by modeling 2D fluid and heat transport within subducting ocean crust using a finite
element heat and mass transport code. The effect of hydrothermal circulation is quantified by
comparing results from simulations with coupled fluid and heat transport to those from simulations with
only heat conduction (no fluid flow). We examine how convergence rate and subduction geometry
influence hydrothermal circulation and temperatures within the subduction zone. Modeled geometries
mimic the Middle America subduction zone off Nicoya Peninsula, and the subduction zone. We simulate
fluid and heat flow for systems with upper basaltic basement permeability ranging from 10-13 to 10-10
m2. Additionally, we examine the effect of permeability reduction within the basaltic basement as it is
subducted. For lower permeabilities, the models with fluid transport show suppressed temperatures
along the subducting slab relative to purely conductive models. At higher permeabilities, large
convection cells reduce temperatures far into the subduction zone and transport heat seaward towards
the trench; temperatures at the toe of the margin wedge become elevated relative to the case with no
fluid flow. Permeability reduction with depth limits how far into the subduction zone significant
hydrothermal circulation can persist.
Keywords: subduction, zone, hydrothermal