HR: 1330h
AN: GP13B-12    [Abstracts]
TI: Remagnetization Overprints in the Upper Ordovician Kope Fm., Kentucky
AU: * MacDonald, W D
EM: wdmacdon@binghamton.edu
AF: Dept. Geological Sciences, State University of New York, Vestal Parkway East, Binghamton, NY 13902 United States
AU: Ellwood, B B
EM: ellwood@geol.lsu.edu
AF: Dept. Geology and Geophysics, Louisiana State University, E235 Howe-Russell,, Baton Rouge, LA 70803 United States
AU: Brett, C
AF: Dept. Geology University of Cincinnati, 500 Geology/Physics Bldg, Cincinnati, OH 45221 United States
AU: Cioppa, M T
EM: mcioppa@uwindsor.ca
AF: Earth Sciences Dept., University of Windsor, 401 Sunset Ave,, Windsor, ON N9B3P4 Canada
AB: The Upper Ordovician (Edenian) Kope Formation was sampled at 61 stratigraphic levels in four overlapping sections in northern Kentucky. Although the objective was to evaluate the usefulness of remanence for magnetostratigraphic correlations between these sections, the samples, mainly silty limestones and siltstones, are pervasively remagnetized. The NRM directions are well-grouped, slightly steeper than the expected present field direction. However, AF and thermal demagnetization, up to 100 mT a.f. peak field and 380§C respectively, reveal remagnetization trends in vector orthogonal and stereographic plots. Endpoints and break-points in these remagnetization trends are consistent with the expected field directions calculated for this locality from Ordovician and Permian (Kiaman) reference poles for North America. The predominance of the overprints obviates the use of remanence for stratigraphic correlations of the Kope sections sampled. Poles computed from the remagnetized directions are compared with Ordovician and Permian poles for North America.
DE: 1520 Magnetostratigraphy
DE: 1533 Remagnetization
DE: 1540 Rock and mineral magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly