BEDROCK GEOLOGY OF THE LAKE SUNAPEE AREA, NEW HAMPSHIRE

The bedrock geology surrounding Lake Sunapee, NH, displays complex relationships formed during the Acadian mountain-building event. Geologic mapping and geochemical analyses of rocks from this area are being undertaken to investigate relationships between structural development, magmatism and metamorphism during mountain-building events, and to improve our knowledge of the distribution of different rock types and structures which may have implications for hydrology, water quality and the environment.

Two large, sheet-like bodies of intrusive igneous rock (very similar granodiorites) are separated by a narrow belt or septum of deformed and metamorphosed sedimentary rocks. This septum is a locus for 1) shearing between the two large plutonic sheets, 2) intrusions of other igneous rock including more mafic material, with a variety of interesting cross-cutting relationships and igneouse textures, and post-orogenic two-mica granite, and 3) later faulting.