LITHODEMES, PSEUDOTACHYLYTE, ULTRAMYLONITE, MYLONITE AND STRIPED GNEISS WITHIN THE NORUMBEGA FAULT SYSTEM, SOUTH–CENTRAL AND CENTRAL MAINE
Additionally, within the system there are migmatite or migmatite – like rocks with an along strike length of 50 to 80 km that are one of the more significant regional units within this area. Within the sheared migmatized outcrop, the mylonites are coarser grained with porphyroclasts up to 1 cm. Granitoid boudins of varying size commonly exhibit a sigmoidal shape consistent with dextral shear. Striped gneiss is uncommon with the exception of a 160 to 240 meter – wide zone which forms the southeastern boundary of the Norumbega Fault System with the coastal lithotectonic belt. The disrupted units and migmatite qualify as lithodemes following the definition of the North American Stratigraphic Code.
Casco Bay Group formations in south – central Maine exhibit a variety of fault generated structures such as pseudotachylyte, phyllonite, mylonite and ultramylonite. Casco Bay Group correlatives in central Maine are locally characterized by numerous, thin pseudotachylyte injection veins. Ultramylonite in south – central Maine ranges in width from a < 15 cm to ~ 40 m. Cross cutting relationships and other features strongly suggest that some of the ultramylonite represents deformed pseudotachylyte.