HR: 1340h
AN: V23C-1559    [Abstracts]
TI: Insights Into the Evolution of the SW Laurentian Margin: Geochronological Constraints From the Paleoproterozoic Farmington Canyon Complex, Utah
AU: * Stroud, M M
EM: stroud@ufl.edu
AF: University of Florida, 241 Williamson Hall, Gainesville, Fl 32606,
AU: Foster, D A
EM: dafoster@ufl.edu
AF: University of Florida, 241 Williamson Hall, Gainesville, Fl 32606,
AU: Mueller, P A
EM: mueller@geology.ufl.edu
AF: University of Florida, 241 Williamson Hall, Gainesville, Fl 32606,
AU: Mogk, D W
EM: mogk@montana.edu
AF: Montana State University, P.O. box 173480, Bozeman, Mt 59717,
AU: Wooden, J L
EM: jwooden@usgs.gov
AF: USGS-Stanford Ion Microprobe Facility, Green Building Rm 89, 367 Panama Street, Stanford, CA 94305,
AB: The Farmington Canyon Complex (FCC) of northeastern Utah is located near the southwestern margin of the Archean Wyoming Province. It constitutes the largest exposure of Early Paleoproterozoic crust along the southwestern Laurentian margin and is comprised of quartzofeldspathic gneisses and migmatites intercalated with amphibolites and metasedimentary rocks. Previous work, based partly on Archean Sm-Nd model ages, suggested an Archean age for the FCC. While new whole rock common Pb data confirm the predominantly Archean source of the metasedimentary rocks, the presence of ca. 2.4 Ga detrital zircons constrains the depositional age of the protoliths to the Early Paleoproterozoic. Zircons from an orthogneiss yield a U-Pb crystallization age of ~2.44 Ga and suggest an age of metamorphism at ~1.8 Ga. These data suggest the rocks exposed in the Farmington Canyon Complex comprise a Paleoproterozoic rift assemblage that probably formed on extended Archean crust along the margin of the Wyoming Province. Igneous rocks produced during this extension were overlain by detritus predominantly, although not solely derived, from the Wyoming Province. The igneous rocks and metasedimentary protoliths were then deformed together during the ~1.8 Ga metamorphic event resulting from accretion of Proterozoic and Archean blocks now to the west and southwest. By constraining the primary depositional and crystallization ages of these rocks in conjunction with their metamorphic and cooling histories, comparisons can be made with the tectonic histories of other Paleoproterozoic belts along the southwestern margin of Laurentia, like the Great Falls Tectonic Zone. These constraints are necessary to test models of possible Neoproterozoic conjugates, and to establish the piercing points critical to a more accurate reconstruction of Neoproterozoic global paleogeography, and the supercontinent Rodinia.
DE: 8110 Continental tectonics: general (0905)
DE: 8199 General or miscellaneous
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting