FABRIC ANALYSIS IN MYLONITE IN THE NORUMBEGA SHEAR ZONE SYSTEM, FREEPORT-HARPSWELL AREA, SOUTHERN MAINE
Five specimens were selected from the Freeport, Maine area to be compared to mineral and porphyroblast data from nine specimens previously studied. Pairs of perpendicular thin sections were cut from each according to fabrics, one parallel to lineation, and perpendicular to foliation, and the other perpendicular to both (X-Z and Y-Z planes, respectively; 10 sections). Collected data include mineral composition. Microstructural data include the shape, geometry, and orientation of matrix fabrics (Se), porphyroblast sizes and shapes, and inclusion trail (Si) geometries and orientations (where present), and Si/Se pitches. Mineral content, shape, orientation, and size of porphyroblast strain-shadow tails is also recorded. Results show matrix mineral compositions are noticeably similar to the South Harpswell area rocks (majority Qtz+Ms+Bt), and have strongly-developed, sub-parallel planar and linear fabrics (Se). In contrast to South Harpswell rocks, garnet porphyroblasts in our current study are not as frequent, or as large. Rocks are relatively more quartzo-feldspathic with similar planar and linear fabrics defined by metamorphic minerals. Rocks of the present study are complimentary to rocks of previous work, and we interpret they have recorded strong non-coaxial strain associated with deformation in the NSZS.