CONTACT METAMORPHISM OF THE KITTERY FORMATION AT CAPE NEDDICK, MAINE

The Kittery Formation is an Ordovician(?)- to Early Silurian-age sequence of feldspathic and calcareous ankeritic metaturbidites that spans from the coast of southern Maine into northern coastal Massachusetts. The Cape Neddick Complex is a Cretaceous- to Jurassic-age igneous body, believed to be the magma chamber of a Mesozoic volcano that intruded the Kittery Formation in York, Maine. During the emplacement of igneous bodies at depth, contact metamorphism of the surrounding country rock occurs, due to the high temperatures produced by the intrusion, and the increased pressures at depth. Samples of the Kittery Formation were collected from the contact with the Cape Neddick Complex. Cordierite was identified in hand sample and thin section and supported using Energy Dispersive Spectroscopy (EDS). EDS also showed inclusions of spinel in orthopyroxene. Spinel-cordierite geothermometry provides a peak temperature estimate of 1110ºC, while the reaction of ms + qtz = kfs + bt + sil + melt constrains the lower temperature boundary to ~650ºC at 1 to 3 kilobar.