HR: 1340h
AN: T53B-1301    [Abstracts]
TI: Comparison of Analytical Results from MIR Spectroscopy, Micro-Raman Spectrography, and Petrographic Examination of Serpentinized Samples from the Atlantis Massif: IODP Expedition 304/305, Hole U1309D
AU: * Fryer, P
EM: pfryer@hawaii.edu
AF: SOEST/HIGP Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96821, United States
AU: Hamilton, V E
EM: hamilton@higp.hawaii.edu
AF: SOEST/HIGP Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96821, United States
AU: Sharma, S K
EM: sksharma@soest.hawaii.edu
AF: SOEST/HIGP Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96821, United States
AU: Zinin, P V
EM: zinin@soest.hawaii.edu
AF: SOEST/HIGP Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96821, United States
AU: Shipboard Scientific Party, I
EM: dblackman@ucsd.edu
AB: The composition and texture of serpentinized dunite and troctolite intervals in gabbroic rocks from IODP Hole U1309D vary downhole, with the most altered, olivine–rich sequences generally in proximity to more highly fractured intervals in the cores. Detailed analysis of samples from the heavily serpentinized intervals, using middle infrared (MIR) spectroscopy and micro-Raman spectrographic analysis shows the utility of these techniques for rapid determination of modal mineralogy, effects of foliation (from fractures, vein-development, and/or mineral alignment), and secondary alteration affecting the rocks. Although spectra of serpentines in the MIR exist, there are essentially none aimed at discrimination of serpentine phases, determination of bulk serpentinite modal mineralogy, or bulk serpentine orientation. Comparison between MIR spectroscopy results and the petrographic and micro-Raman analysis of the samples show that, to a first order, MIR spectroscopy gives indication of the effect of bulk rock foliation originating from preferred serpentine orientation and fracture patterns in the rocks. MIR spectroscopy also provides a method for quickly and inexpensively analyzing large numbers of samples as triage to maximize scientific return from more detailed analysis. We have performed micro-Raman analysis, using polished thin sections, of serpentinized olivine-rich samples from IODP Expedition 304/305 and are able to map not only primary and minor phases, but are able to identify regions within serpentinized portions of the samples that show intergrowths of serpentine with secondary alteration phases on a scale of a few microns.
DE: 1032 Mid-oceanic ridge processes (3614, 8416)
DE: 3035 Midocean ridge processes
DE: 3614 Mid-oceanic ridge processes (1032, 8416)
DE: 3625 Petrography, microstructures, and textures
DE: 3934 Optical, infrared, and Raman spectroscopy
SC: Tectonophysics [T]
MN: 2007 Fall Meeting