Second posting / please note correction to list of confirmed speakers!
We invite your contribution to GSA 2009 session T45: Growth and
Stabilization of Continental Crust in Circum-Pacific Accretionary Orogens.
The dates of the GSA meeting are October 17-21, 2009, and info on the
meeting is on line at http://www.geosociety.org/meetings/2009/ . Abstract
deadline is October 11.
Conveners: Christine Siddoway (ISES co-organizer '06-'08) and David Foster
Confirmed keynote Speakers: C. Mark Fanning, Stephen T. Johnston, and
Patrice Rey
Rationale:
Accretionary orogens formed at subduction margins are sites of continental
growth attributable to arc magmatism, erosion of the upper plate, and
transfer of material from the down-going to the overriding plate. The
circum-Pacific regions contain a repository of information about crustal
growth by diverse mechanisms. An "accretionary orogen" GSA session will be
timely in 2009 due to developments in two subject areas over the past three
years. These are 1) isotope geochemistry and geochronology of
magmatic/metamorphic belts around the circum-Pacific region that bring into
question long-standing interpretations of magmatic arc processes. The
recognition of a mantle component in the generation of I-type granites in
the Lachlan Orogen signifies that the granites cannot be attributed wholly
to fractionation and assimilation. 2) Structural geology and geophysics
identify examples of dramatic supra-subduction zone extension, sedimentary
infilling, and basin inversion followed by intense contraction events that
served to transform primitive oceanic crust with sedimentary cover into
continental crust of ordinary thickness.
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