ISSN:
1525-1314
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
There is no significant difference in the diffusion profiles across albite-adularia bicrystals that were simultaneously deformed at a strain rate of 10-6S-1 and those from hydrostatic experiments at the same conditions (1500 MPa and 1000°C for 156 h). This indicates that the bulk alkali diffusion rate, which is the sum of lattice diffusion (D, 1) and dislocation pipe diffusion (Dp), is not significantly enhanced by dislocations at these conditions, and that the maximum value for the ratio of Dp/D1 is about 105. This is equal to the value previously reported for‘oxygen’diffusion in albite. If this ratio is independent of temperature, the contribution of either static (pre-deformed) or moving (syn-deformed) dislocations to the bulk diffusion rate of alkalis is probably minor at all metamorphic conditions. For Al and Si diffusion the ratio of Dp/D1 may be larger if D1 is lower. Thus a significant contribution from dislocations to bulk diffusion cannot be ruled out, especially during simultaneous deformation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1525-1314.1989.tb00601.x
