HR: 0800h
AN: GP21A-0104    [Abstracts]
TI: En Bloc vs. Standard Tilt-tests and the Problem of Initial Dip in Paleomagnetic Studies.
AU: * MacDonald, W D
EM: wdmacdon@binghamton.edu
AF: State University of New York, Department of Geological Sciences, Vestal Parkway East, Binghamton, NY 13902, United States
AU: Palmer, C
EM: cpalmer@uwo.ca
AF: University of Western Ontario, Department of Earth Sciences, UWO, London, ON N6A 5B7, Canada
AB: Tilt-tests are standard paleomagnetic tests used to determine if the time of acquisition of remanence predated or postdated the tilting of strata. Partial untilting ('unfolding') tests seek to establish if remanence acquisition occurred during deformation of the strata. These kinds of tests assume that 1) tilting involved a rotation about the line of strike and 2) that the stratification (bedding) was horizontal at the time of deposition. If either one of these premises is incorrect, then incorrect conclusions may be drawn from the results of the tilt test. Although sedimentary environments on continental platforms or at abyssal depths tend to be dominated by quasi-horizontal strata, volcanic deposits commonly exhibit significant initial dip. This study explores initial dip effects in the early Tertiary Caetano Formation of Nevada, and compares en bloc tilt correction results with those of the standard tilt-test. Inferences about the degree of initial dip present can be drawn from the results. Caveats relevant to initial dip and the tilt-correction are summarized.
DE: 1520 Magnetostratigraphy
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting