sgr ms thesis - University of Maine

6.3.3. Clast Circularity Analysis (CCA) Data
Circularity data were collected for 8,724 outlined clasts over three orders
of magnitude for Shatter Zone Types 1-3 (Figure 6.13). Many of the same clasts
used for CSD were used for CCA. Type 1 clasts have the lowest average
circularity value of 0.48, and the circularity averages for the 0.1-1cm, 1-10cm,
and >10cm intervals are 0.54, 0.36, and 0.19, with population sizes of 925, 431,
and 5, respectively. Type 2 clasts have an average circularity of 0.58, and the
circularity averages for the 0.1-1cm, 1-10cm, and >10cm intervals are 0.61, 0.47,
and 0.27, with population sizes of 2,155, 595, and 9, respectively. Type 3 clasts
have the highest degree of circularity with an average of 0.76, and the circularity
averages for the 0.1-1cm, 1-10cm, and >10cm intervals are 0.77, 0.67, and 0.63,
with population sizes of 3,945, 644, and 14, respectively.
6.3.4. Summary of Data
All three types of Shatter Zone yield a value of D s above 2.5 for
distributions of radius greater than 1cm. Below this clast size, D s varies greatly
but is always lower than the D s of the coarser size range. The “breakpoint” in the
bifractal slope occurs over a small and consistent size range in Types 1 and 2.
Data from Types 1 and 2 come dominantly from Bar Harbor Formation clasts,
whereas data from Type 3 is split between diorite dike and Bar Harbor Formation
clasts. Magmatic fabric dominates in Type 3, with no clast preferred orientation.
Granitic matrix becomes more abundant with proximity to the Cadillac Mountain
Granite interface. Circularity increases with proximity to the intrusive contact and
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