The GSA abstract deadline approaches for "Growth and Stabilization of
Continental Crust in Circum-Pacific Accretionary Orogens," a Topical Session
at the Annual Meeting in Portland, Oregon, USA. Abstract submissions are
due by August 11.
We welcome papers addressing the growth and evolution of continental crust
during circum-Pacific ocean-continent convergence, including transient
extensional, contractional and transcurrent events that affect the
overriding plate. The session will offer perspectives from diverse
disciplines, including geodynamics, tectonics, metamorphism, magmatism and
geochemistry/geochronology.
The session rationale is provided below. Keynote talks to open the session
will explore the Andean margin of Patagonia, the Tasman orogen of
Australia-Antarctica, and the North American Cordillera, with speakers to
include C. Mark Fanning, Australian National University; Stephen T.
Johnston, University of Victoria, British Columbia; Patrice Rey, University
of Sydney, Australia.
Abstracts may be submitted online at http://gsa.confex.com/gsa/2009AM/cfp.epl .
Dates of the meeting are October 17-21, 2009, with info and submission
instructions at http://www.geosociety.org/meetings/2009/ .
Please help to distribute the session information widely!
Sincerely,
Christine Siddoway and David Foster
Co-conveners
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Session Type: Oral/Poster 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.
This topical session, devoted to the advances in studies of arc magmatism
and of intraplate deformation, will enhance our understanding of the
geodynamics of oceanward growth and the fundamental mechanisms responsible
for stabilization of continental crust. New results from geochronology shed
light on the time scales of continental growth and stabilization, and the
possibility of cyclicity of episodic events during continent-ocean convergence.
Notice: Speakers may present two volunteered abstracts during the Annual
Meeting, as long as one of these abstracts is a poster presentation. All
oral presentations are scheduled to be 15 minutes long.
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