Reaction-enhanced permeability during serpentinite dehydration
- 1Research School of Earth Sciences, Australian National University, Canberra ACT 0200, Australia
- 2Research School of Earth Sciences and Department of Geology, Australian National University, Canberra ACT 0200, Australia
Abstract
Fluid mobilization during prograde metamorphic reactions is a poorly understood, yet crucial, phenomenon that has implications for a number of geologic problems. Here we present the first experiments to characterize permeability evolution during dehydration of a natural rock. Dehydration of serpentinite specimens resulted in the generation of pore space and the rapid development of an interconnected pore network. During breakdown of antigorite to olivine + talc + H2O, permeability increased rapidly by at least three orders of magnitude. In natural systems, such an increase in permeability would be transitory, because high confining stresses would rapidly eliminate the porosity generated during reaction. Such transitory, reaction-enhanced permeability of serpentinite provides a mechanism by which fluids can migrate and possibly facilitate subduction-zone seismicity and contribute to partial melting of the mantle wedge. The results presented also have implications regarding middle- to deep-crustal fluid flow.
Footnotes
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↵GSA Data Repository item 2003132, a detailed description of the permeability measurement technique, is available online at www.geosociety.org/pubs/ft2003.htm or on request from editinggeosociety.org or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301-9140, USA.
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- Accepted July 8, 2003.
- Received April 7, 2003.
- Revision received June 26, 2003.
- Geological Society of America
