Quantitative characterisation of cataclasites using a statistical approach (analysis of variance)
- Author(s)
- Norbert Kohlmayer, Bernhard Grasemann
- Abstract
Cataclastic rocks can be described by both a range of shape parameters and the particle size distribution. In this work, we apply statistical methods to investigate these variables in samples with different degrees of maturity from high- and low-angle normal faults within marbles in the W-Cyclades (Greece). Four shape parameters (circularity, elliptical PARIS factor, solidity and the aspect ratio) were used to describe the particles. Using a statistical analysis, the variance of the cataclastic particles of a particular shape is partitioned into fractions attributable to different sources of variation. In addition to the shape parameters, the particle size distribution was included, to test whether there is a relationship between particle size and shape. The investigations demonstrate that the analysis of variance is a statistical method ideally suited for quantitatively studying the grain-size and shape parameters in cataclasites. Our results indicate that although the particle size distributions of the test samples are very similar, three shape parameters (solidity, circularity and the elliptical PARIS factor) can discriminate between the samples. Ideally, numbers of the shape parameter discretized in individual classes of equivalent diameter of the particle components should be used to quantitatively describe the different samples in order to derive information about the deformation mechanisms in the fault rock. Some of the investigated shape parameters record a clear dependence on the grain-size. In the investigated samples, smaller particles record a higher circularity and a lower elliptical PARIS Factor than larger particles. However, no relationship between the solidity or aspect ratio and the grain size has been observed. This suggests that abrasion and comminution are the dominant deformation mechanism in the finer grained particles but fracturing and cracking are prevalent in the more angular, coarser grained particles.
- Organisation(s)
- Department of Geology
- Journal
- Austrian Journal of Earth Sciences
- Volume
- 105
- Pages
- 48-60
- No. of pages
- 13
- ISSN
- 0251-7493
- Publication date
- 2012
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105124 Tectonics
- Keywords
- ASJC Scopus subject areas
- Geology, Stratigraphy, Palaeontology
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/fa5a1f91-070f-449d-90aa-6d93fe1cc793