Experimentally produced deformation lamellae in quartz. The deformation lamellae are the fine black lines in an oblique orientation (NNE-SSW) at the very left of the picture and along the EW trending band in the central part. These lamellae were produced in DRY quartz single crystals. The c-axis was oriented at 45 degrees to the compression direction. Compression direction was NS (vertical) in the pictures and the c-axes oriented NW-SE in the plane of the thin section.

The lamellae were formed at 800 degrees Celsius and a confining pressure of about 1200 MPa in a Griggs solid medium apparatus at a bulk differential stress of about 1600 MPa. Presently (Mai 2000) Dominique Wittmer is setting up a Griggs machine in our rock deformation laboraty in Zürich and carries out a series of deformation experiments to investigate the effect of crystallographic orientation of the quartz crystals w.r.t. the compression direction on the orientation of the lamellae.

You may find more about ductile deformation of quartz at the homepage of Brown University Structural Geology group.

10 Mai 2000