HR: 14:40h
AN: T43E-05    [Abstracts]
TI: The Water Cycle Within Subducting Lithospheric Slabs
AU: * Robin, P F
EM: py.robin@geology.utoronto
AF: Robin, Pierre-Yves, Department of Geology University of Toronto 22 Russel St, Toronto, ON M5S 3B1 Canada
AU: Robin, C M
AF: Robin, Catherine, Department of Physics University of Toronto 60 St. George St, Toronto, ON M5S 1A7 Canada
AB: A significant amount of water can be transported deep into Earth's upper mantle by descending lithosphere: several minerals can indeed bring it down to the `transition zone', where spinels then dissolve it and transport it further down. Because lower mantle minerals can only incorporate a very small fraction of that water, it is released at the bottom of the transition zone and enters a `Slab Water Cycle' that is indeed mostly located within the subducting slab and between the bottom of the transition zone and Earth's surface. That released water percolates upward within the slab, and (a) is incorporated into descending spinel, (b) eventually ascends above the transition zone and up to the hydrosphere, and/or, (c) leaks into adjacent mantle. Percolating water readily accounts for deep-focus earthquakes and for some features of intermediate focus earthquakes. It should also have a significant impact on location and geochemistry of fluids and melts generated in the upper mantle
DE: 8120 Dynamics of lithosphere and mantle--general
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting