Abstract
Para- and ferro-magnetic fabrics are known to provide essential clues
for understanding impact cratering processes. However, research on the
effects of shock waves on diamagnetic fabrics is lacking. We, therefore,
conducted a hypervelocity impact experiment on a block of diamagnetic
Taunus quartzite and studied the changes in diamagnetic fabrics. In the
crater subsurface, the reorientation of the diamagnetic fabrics is
concentrated in a zone of ~4 projectile diameters (25
mm) width directly below the point of impact. Higher reorientation in
this zone indicates the concentration of damage. We argue that although
the shockwaves traversed through the target with a hemi spherical
wavefront, the damage was concentrated directly below the point of
impact.
Another important observation is that the weak shock waves have changed
the diamagnetic parameters. The bulk susceptibility has increased
overall, while the corrected degree of anisotropy (P’) and the shape
parameter (T) have increased in the crater subsurface but have decreased
at the target surface. We propose that the variable response of P’ and T
could be due to the difference in incident angle subtended by the shock
wave on the diamagnetic foliation at the target surface (c. 34°) and in
the subsurface (c. 54°). These results, thus, show that the changes in
diamagnetic fabrics can be used as a proxy for plastic deformation
caused by shock waves at low peak pressures.