Journal
JOURNAL OF STRUCTURAL GEOLOGY
Volume 32, Issue 1, Pages 59-69Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jsg.2009.08.002
Keywords
Cataclasite; Rock deformation; Microstructures; Seismic deformation; Grain size
Categories
Funding
- Freiwillige Akademische Gesellschaft
- Zentrum of Microscopy of Basel University
Ask authors/readers for more resources
Microstructures and grain size distribution from high velocity friction experiments are compared with those of slow deformation experiments of Keulen et al. (2007, 2008) for the same material (Verzasca granitoid). The mechanical behavior of granitoid gouge in fast velocity friction experiments at slip rates of 0.65 and 1.28 m/s and normal stresses of 0.4-0.9 MPa is characterized by slip weakening in a typical exponential friction coefficient vs displacement relationship. The grain size distributions yield similar D-values (slope of frequency versus grain size curve = 2.2-2.3) as those of slow deformation experiments (D = 2.0-2.3) for grain sizes larger than 1 mu m. These values are independent of the total displacement above a shear strain of about gamma = 20. The D-values are also independent of the displacement rates in the range of similar to 1 mu m/s to similar to 1.3 m/s and do not vary in the normal stress range between 0.5 MPa and 500 MPa. With increasing displacement, grain shapes evolve towards more rounded and less serrated grains. While the grain size distribution remains constant, the progressive grain shape evolution suggests that grain comminution takes place by attrition at clast boundaries. Attrition produces a range of very small grain sizes by crushing with a D-<-value = 1. The results of the study demonstrate that most cataclastic and gouge fault zones may have resulted from seismic deformation but the distinction of seismic and aseismic deformation cannot be made on the basis of grain size distribution. (C) 2009 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available