HR: 1330h
AN: V12A-0567    [PDF]
TI: Quantifying Three-Dimensional Silicate Fabrics in Cumulates Using Cumulative Distribution Functions
AU: * Gee, J S
EM: jsgee@ucsd.edu
AF: Geosciences Res. Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0220 United States
AU: Meurer, W P
EM: William.P.Meurer@mail.uh.edu
AF: Dept. Geosciences, Univ. Houston, Houston, TX 77204-5007 United States
AU: Selkin, P A
EM: pselkin@ucsd.edu
AF: Geosciences Res. Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0220 United States
AU: Cheadle, M J
EM: Cheadle@uwyo.edu
AF: Dept. Geology and Geophysics, Univ. Wyoming, Laramie, WY 82701 United States
AB: We present a new method for quantifying three-dimensional silicate fabrics and the associated uncertainties from grain orientation data on three orthogonal sections. Our technique is applied to the orientation of crystallographic features and hence yields a fabric related to the lattice preferred orientation, although the method could be applied to shape preferred orientations or strain analysis based on passive linear markers. The orientation data for each section are represented by their cumulative distribution function (CDF), and an iterative procedure is used to find the symmetric second rank strain tensor that will simultaneously satisfy the CDFs observed on each section. For samples with well-developed fabrics, this technique provides a much closer match to the sectional data than do previous techniques based on eigenparameter analysis of two-dimensional orientation data. Robust uncertainty estimates are derived from a nonparametric bootstrap resampling scheme. The method is applied to two cumulates, one with a well-developed fabric and the other with a weak fabric, from the Stillwater complex, Montana. The silicate petrofabric orientations obtained for these samples with this new method compare favorably to independent direct estimates of the volume fabric from electron backscatter diffraction and magnetic techniques.
DE: 1518 Magnetic fabrics and anisotropy
DE: 1527 Paleomagnetism applied to geologic processes
DE: 8434 Magma migration
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting