It STARTED IN THE FIELD, AND SOME OF “It” IS STILL THERE: REVISED BEDROCK GEOLOGY OF THE LINCOLN AREA, E-CENTRAL ME

Results of 2007-2009 mapping mandate significant changes in the east-central part of the 1985 Maine bedrock geologic map that in turn require reassessing the reasoning inherent in lithostratigraphic interpretations depicted on that map. SW extent of the Aroostook-Matapedia (AM) sequence: Clear distinctions between the Carys Mills (mostly limestone) and Smyrna Mills (mostly pelite) formations near Houlton blur along strike to the southwest. The closure shown on the 1985 map is approximately correct, but the two formations cannot be distinguished south of the Center Pond pluton. Central Maine Boundary Fault (CMBF): The line tracing CMBF on the 1985 map is actually a zone of intense disruption more than 5 miles wide that includes both AM pelitic strata and CM sandstones. This zone, here named the Dexter shear zone, is the widest of three such chaotic zones in the region, each located between thick-bedded sandstone and thin-bedded, largely pelitic units. The 1985 interpretation that the CMBF separates the Central Maine sequence (CM) from AM is probably no longer tenable, although the structure truncates CM units locally. Miramichi terrane south of the Bottle Lake pluton: Detailed mapping reveals multiple folding and an unusual Fe-Mn unit associated with Ordovician arc-related volcanic rocks. Adjacent rocks on the east shown as Vassalboro (CM) but potentially Flume Ridge (Fredericton belt) are neither. Three formation rank units lying between the Miramichi and rocks continuous with the Fredericton are probably traceable to CM rocks in the Bangor area recently remapped by Pollock.