Dear Sebastian,
X-ray texture goniometry (XTG) is used primarily for the quantification of
fabric intensity in clay-rich rocks, as it provides information for the
orientation of large numbers of very small particles in three dimensions. As
clay minerals are too small to measure conveniently by optical or EBSD methods,
measuring the relative intensity of a single clay XRD peak, while continuously
changing the orientation of the sample relative to the beam provides
information both about the orientation of clays within a sample, and the
intensity of that orientation. The technique is normally used to look at
structural problems in clay-rich rocks such as the relative roles of grain
rotation and new clay growth during diagenesis in sedimentary basins, the
mechanisms involved in the shale-slate transition, and clay fabric orientation
and intensity in clay-rich fault gouges and experimentally-sheared materials.
Haines et al., (2009), JGR B vol. 114, doi:10.1029/2008JB005866 has a summary
of the technique and some it's applications to clay-rich rocks, primarily fault
gouges. van der Pluijm et al., (1994) J. Struct. Geol. vol.16, pp. 1029-1032
gives details of the analytical technique and discusses sample preparation. Let
me know if you would like .pdf's. The 2ed edition of Passchier and Trouw's
Micro-tectonics (2005) also contains a useful summary somewhere in Chapter 10.
Although very useful, the technique is unfortunately not widely used, owing to
the fact that XTG machines are usually 'home-modified' XRD units, rather than
'off-the-shelf' purchased machines. Ben van der Pluijm at Michigan has one, so
does Hans Wenk at UCLA, and Manuel Sintubin at Leuven in Belgium has one.
Workers interested in using the technique usually collaborate with one of these
labs, with the Michigan lab the most active in the last few years. Are list
members aware of any other XTG units?
Best,
Sam
---------------------------------------------
Sam Haines
Post-Doctoral Fellow
Department of Geosciences
Pennsylvania State University
510 Deike Bldg.
University Park, PA, 16802
USA/EE UU
+1-814 865-1527 (Office phone)
+1-814 863-7823 (Office fax)
+1-734-646-0512 (Mobile)
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