sgr ms thesis - University of Maine

and non-fractal distributions (Jebrak, 1997; Clark and James, 2003). The matrix
only makes up 16% of volume in Type 1; therefore there would have been
enough heat to disaggregate small clasts, but not large ones, assuming that the
local matrix percentage by volume is greater than 16% in the magma channels
that hosted the smaller clasts (hypothetically, clasts with radius greater than
1.25cm saw little effect of disaggregation). This agrees with the high intensity,
large D s value for larger clast sizes (D s >3) and a low intensity, small D s value for
finer clast sizes (D s =1.5) because they are defined by differing mechanisms. The
D s values for the fine clast range of Type 1 are within the hydraulic brecciation
range. It is possible that clasts were host to fluid and thermal assisted fracture,
which would produce a D s below 2. The original fine clasts could have
disaggregated during magma intrusion, then new small clasts formed by thermal
fracture could produce a D s value similar to what are seen for the fine Type 1
distributions.
For Type 2, D s increases to 3.17 for the coarse clast size range and 1.875
for the fine range, with a breakpoint at 1.52cm. The matrix of Type 2 composes
34% of total volume, therefore there is greater potential for disaggregation of
small clasts. The D s value for the fine clast ranges of Type 2 is greater than Type
1, which may imply a greater intensity of fluid and thermal assisted fracture at the
fine scale.
Whereas D s values for the fine distributions of Types 1 and 2 imply a low
energy manner of formation, D s for coarse size distributions are above 3 for
Types 1 and 2, implying a high intensity mechanism. The two most viable
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