sgr ms thesis - University of Maine

6.1.1.2. Type 2. The observed breccia pockets seen in Type 1 may be a
precursor to those of Type 2 (Figure 6.3), which shows a greater frequency of
higher intensity breccia pockets and is deemed to represent the intermediate
stage in the developmental brecciation time scale. The Type 2 locality is along
Seely Road, located south of the Type 1 location (44.36303, -68.18332).
Brecciation in Type 2 outcrops appear to be more chaotic with minimal
preservation of the original bedding structures (Figure 6.6). Again, all matrix
material is fine grained and there is no evidence for late stage fracture. Diorite
dikes are more frequent, and some are brecciated.
6.1.1.3. Type 3. Type 3 Shatter Zone is the most evolved stage of
brecciation, in which isolated clasts are abundant, generally sub-equant, and
completely suspended in granite matrix (Figure 6.4). The Type 3 locality is on
Great Head, in the southeastern section of the island (44.32872, -68.17986). The
observed clasts in the Type 3 breccias are dominantly diorite, which contrasts
with Types 1 and 2. Many clasts appear well rounded with concentrations of
biotite along their rims. The matrix is generally fine grained with pegmatitic
material present in late stage cracks. Evidence for late stage cracking in diorite is
not uncommon. Many of the Bar Harbor clasts appear to have recrystallized, and
the most abundant Bar Harbor Formation clasts appear to be from the more
resilient layers. There are no flow textures in the matrix except for occasional
local features that apparently formed from minor clast rotation and settling
(Figure 6.7).
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