Dear Colleagues,
This is a quick heads-up on a special session, at AGU in December, focusing
on metamorphic geochemistry and fluid-rock interactions in subduction zones.
We encourage you all to submit abstracts. Bear in mind that we seek
contributions that are relevant to metamorphic processes during subduction,
but this does not mean that all abstracts need necessarily pertain directly
to blueschists and eclogites (although we do love blueschists and
eclogites!). Serpentinites, pelitic schists, amphibolites, peridotites,
even (gasp!) igneous rocks are also welcome, as well as broader theoretical
and experimental studies. Please pass this message on to anyone who might
be interested.
The abstract deadline is September 10, 2008. Abstracts can be submitted by
following this link:
http://www.agu.org/meetings/fm08/index.php/Program/SessionSearch
Please be sure to select session V20.
The meeting will be held December 15-19 in San Francisco. Further details
can be found at http://www.agu.org/meetings/fm08/. Any questions may be
directed to any one of the conveners.
See you in December!
Best Regards,
Maureen Feineman
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Gray Bebout
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Jay Ague
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Ivan Savov
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Session details:
V20: Subduction Zone Metamorphism: Fluid-Rock Interaction in Time and Space
Conveners: Maureen Feineman, Gray Bebout, Jay Ague, and Ivan Savov
Invited Speakers: Ralf Halama, Sarah Penniston-Dorland, Yue (Merry) Cai
This session will explore the use of metamorphic geochemistry as a means of
illuminating processes taking place beneath the surface within subduction
zones, merging information regarding mineral reaction histories, fluid-rock
interactions, and kinetics, in consideration of the generation and mobility
of (ultra) high-pressure fluids. In contrast to the directly observable
inputs (mostly seafloor sediments and altered basalt) and outputs (mostly
lavas and volcanic gases) of subduction zones, the metamorphic portion of
the subduction factory (the hinge upon which the transition from input to
output turns) is at work entirely beyond our line of sight. What we can
observe directly are the metamorphic underbellies of failed, rifted, or
otherwise exposed subduction zones, which have invariably been subjected to
complex sequences of pro- and retro- grade reactions that must be unraveled
before we can address the important issue of just what fluid-forming and
mobilization processes take place beneath the arc.
Subduction-related metamorphic rocks record a wide variety of pressures,
temperatures, and compositions. However, interpretation of metamorphic
history from mineral assemblages is complicated by the fact that minerals in
a subducting slab are not always able to achieve equilibrium as they
descend. The rate at which reactions proceed is a function of subduction
rate, temperature conditions, and the amount of fluid in the system.
Large-scale fluid-rock equilibration may be unlikely in colder regions of
the subduction zone (i.e. in a fast-descending slab) but may occur more
rapidly in hotter regions of the subduction zone (i.e. the lower mantle
wedge), which in turn may cause chemical variation in subduction-related
fluids. The chemistry of these subduction zone fluids may further be varied
according to the timescales on which they are released – in particular,
whether they percolate in a steady stream or travel in self-contained pulses.
We solicit abstracts pertaining to the geochemistry of all
subduction-relevant metamorphic rocks and minerals, with particular emphasis
on studies pertaining to geochronology and spatially resolved geochemistry
on all scales, from grain boundaries to field-scale investigations.
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