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October 19 @ 4:00 pm - 5:00 pm CDT

EEPS Seminar:  Whitney Behr, University of Texas

Abstract Title:  Geologic heterogeneity and transient rheology of the deep subduction interface

Abstract:

The rheology of the deep subduction interface is fundamental to both large-scale and regional-scale plate dynamics, affecting plate velocities, styles and rates of exhumation of subducted material, and depths and style of seismicity.  In this talk I will demonstrate how observations from the rock record can tell us fundamental information about the mechanical behavior of the deep roots of subduction megathrusts.  I will focus on a spectacularly exposed exhumed analog of a warm subduction zone located on Syros Island in the Cyclades in Greece, which preserves blueschist- and eclogite-facies deformation fabrics within a wide range of protolith rock types (metabasalts, marbles, metavolcanics and metapelites). I will use these rocks to address two primary questions:

1)    What controls the long-term viscosity of the deep subduction interface?

2)    What processes may contribute to episodic tremor and slow slip (ETS) along the deep subduction interface?

I will make the case firstly that the viscosity of the plate interface is highly sensitive to subducted protolith rock type, and that switches from metamafic- to quartz-dominated protoliths with progressive subduction can result in plate velocity changes of up to several cm/yr and can substantially affect the exhumational style within the subduction channel.  I will make the case secondly that smaller-scale heterogeneities within individual subducted protoliths may represent the rock record of ETS events similar to those observed along the deep interface in modern subduction zones (e.g. Cascadia).

Details

Date:
October 19
Time:
4:00 pm - 5:00 pm
Event Category:

Venue

100 Keith-Wiess Geological Laboratories
Rice University, 6100 Main Street, MS 126
Houston, TX 77005 United States
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Phone:
713-348-4880
Website:
earthscience.rice.edu

For outside visitors, the best way to get to our department is to come in on Rice Blvd and turn into entrance 20 (intersection of Rice and Kent St.). At the stop sign, you will see a visitor parking lot.  From there, walk east to the department.  The google map below shows exactly where our building is.