Petrofabric analysis of quartzite from the Bergsdalen quadrangle, Western Norway.

In a flattened quartzite the two symmetrical slip planes are very unequally developed in the biotite (34 and 3 percent) and muscovite (33.5 and 0.5 percent) fabric diagrams. In the quartz diagram a maximum with the remarkable concentration of 37.5 percent Iies 38° from the major slip plane. All diagrams have monoclinic symmetry with the line of intersection between the slip planes as the B axis. Fieid evidence points to this direction as he a axis. Muscovite a axes show strong concentration in this direction, and the position of the quartz maximum proves it to be maximum Ill, both facts confirming the set-urp of fabric axes as determined in the field.
The conclusion must be that the symmetry of fabric diagrams is not aiways a reliable indicator of the direction of tectonic transport.