Projects
In-situ Zircon U-Pb Age Determinations Using
Multiple-Collector Inductively Coupled Plasma Mass Spectrometry: A New
Technique And A Tectonic Application
U-Pb ages can be now measured on single
crystals of zircons using multicollector ICP-MS. High-precision ages can be
determined in-situ by laser ablation techniques, either on previously
concentrated zircon fractions, or directly on thin sections. We can measure
ages on spots as small as 20 microns. The technique has a precision similar to
ion probe techniques but it is faster and cost-effective.
This proposal seeks funding to help
further develop the methodology (30%) and to apply it to a tectonic problem:
resolving the age and provenance of metasedimentary framework rocks within the
Salinian terrane, central California (70%). The technique development component consists of various tests
for the magnitude of U-Pb fractionation in the instrument and better
calibration of ablation rates. The application proposed here is a provenance
study of the Sur Series, an extensive metasedimentary unit in central California. The origin and age of many framework rocks within
the North American Cordilleran arcs (e.g. the California arc) remain unresolved because of high-grade
metamorphic imprint during arc formation. Solving the provenance of the Sur
Series can provide important constraints on the hypotheses of lateral
translations along the continental margin and terrane accretion in the area. We
test between three plausible original locations of the Sur Series: southern Sierra Nevada, southern Mexico, and northern California.
Personnel: Ducea, M.
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Page last updated May 22, 2003. Questions or Comments Mail to mducea@geo.arizona.edu