An autocorrelation method for three-dimensional strain analysis

摘要

We present a method of finite-strain estimation using the autocorrelation properties of deformed rock. Autocorrelation is the correlation of an image with itself as a function of an offset or lag. In two and three dimensions, the lag has both distance and direction. Many geologic materials are initially isotropic, which means that the autocorrelation function (ACF) will be initially isotropic as well. Deformation imposes an anisotropic distortion, which can be measured using the Ramsay and Fry strain methods for example, but can also be estimated from the ACE X-ray tomography now provides a rapid way to measure the three-dimensional ACF of a geologic sample. Strain parameters are estimated by using a non-linear, best-fit method to minimize the anisotropy in the ACF. The ACF method works best for materials where the objects are internally uniform and contrast strongly with the matrix and other grains. (C) 2015 Elsevier Ltd. All rights reserved.