Northeastern Section - 37th Annual Meeting (March 25-27, 2002)

In the recently-mapped Salsbury Cove 1:24000 quadrangle, the Ellsworth Schist comprises two main subdivisions: the Lamoine unit (chlorite-grade) and the Egypt unit (greenschist to epidote amphibolite [McGregor, 1964]). Intrusions include a foliated/lineated high-level granitoid sheet at Lamoine Beach and a variety of late dikes. The Lamoine unit consists of quartz-veined, thinly laminated quartz-albite-muscovite-chlorite schists (probable felsic ash protolith) and competent layers of bimodal greenstones/felsites and sparse massive rhyolites. The main fabric defines a large-scale antiform whose hinge line extends from the lower Jordan River to the lower Skillings River. Asymmetric folds and sigmoidal quartz lenses suggest top-to-northwest kinematics on both limbs of the late antiform. The Egypt unit, which occupies an oblate >100 km² area located mostly north of the Salsbury Cove quadrangle in the core of a late synform, consists of green albite-porphyroblastic schists and several bodies of fine-grained amphibolite. The Egypt unit appears to overlie the Lamoine unit along a concordant contact, which suggests it is allochthonous.

Early Ordovician northwestward emplacement of an accretionary complex (Surry) over Ganderia's southeast margin (St. Croix) explains many features of this region: 1) intense deformation of the Ellsworth Schist; 2) exotic high-grade rocks (Deer Isle peridotite; Egypt amphibolites); 3) great variety of volcanic affinities such as ocean island (North Haven) and island arc (Castine); 4) window of Tremadocian black shales (Bagaduce River); 5) Ordovician termination of sedimentation in the St. Croix terrane; and 6) possibly the sedimentary polarity of the St. Croix margin.