sgr ms thesis - University of Maine

esolution images of each box were stitched to create the image mosaics (Figure
6.9). Clasts were manually outlined from each mosaic in a drafting program to
differentiate between clast and matrix, producing a black (clast) and white
(matrix) image. Manual outlining was required because the grayscale separation
between clasts and matrix was commonly too small to accurately distinguish
them using image analysis software (e.g. Sudhakar et al. 2005). The outlines
were analyzed with NIH ImageJ for clast count, area, circularity, and boundary
shape. CSD, CBS, and CCA data were calculated from these output data. The
number of clasts used for CBS was limited compared to CSD because each
randomly chosen outline had to be analyzed individually.
For CSD of the Shatter Zone breccias, the equivalent radius was used to
plot data on a logarithmic size cumulate frequency plot, with a clast radius
interval of 10 0.02 cm. Only clasts greater than 1mm radius were plotted because
of difficulty in distinguishing between smaller clasts and the granite matrix.
Cumulate frequency was standardized to the total area covered for each outcrop
location to allow better comparison between locations with greater or smaller
outcrop representation. D s values were calculated from equation (5.3).
CBS data were produced by 42 ribbon width and area measurements for
428 clast outlines. Measurements were taken in NIH ImageJ. The log of ribbon
width was plotted with respect to the log of ribbon area, and D r was calculated
from the slope using equation (5.6).
76