Deformation of experimentally shocked biotite

Abstract

Shock experiments (10-40 kb) on lepidomelane show that kinking occurs at pressures as low as 9 kb; the intensity is related to peak pressure and shock pulse duration (0.7-0.3mu sec.), and is produced by shocks propagated along [hk0] and not along [001]. The shock-induced kinks have a wider range of their angle of external rotation (19-121 degrees ) than their static counterparts (40-60 degrees ). The ratio of the kink angles, epsilon and delta , scatters widely, indicating shock induced kinking is highly asymmetrical. A marked decrease of 2V from 24 to 7 degrees with increasing pressure is observed. Laue transmission patterns show that permanent angular rotations as great as 4.4 degrees are induced by shock pressures of 37.5 kb. In individual samples the increase in permanent angular rotations and decrease in 2V can be closely correlated.