KINEMATICS OF THE BOIL MTN. OPHIOLITE - CHAIN LAKES MASSIF CONTACT

Accretion and amalgamation of Iapetan arcs and microcontinents characterizes the pre-Taconian and Taconian history of the northern Appalachians. Kinematic histories of sutures between the numerous architectural components that make up the orogen are essential for reconstructing the tectonic development of the Early Paleozoic Laurentian margin. The contact between the Chain Lakes massif and Boil Mountain ophiolite complex, located in west-central Maine and southern Quebec, represents one such suture. Regional history suggests that rocks of the massif along the contact have experienced at least two deformations, one associated with sillimanite-grade metamorphism of the massif and one associated with ophiolite emplacement. Additional deformations may include Taconian and Acadian reactivation of the contact. Given the many candidates, it is critical to determine the age and event generating a given deformational fabric prior to making tectonic interpretations based on kinematics recorded in that fabric. Supporting the regional interpretations, field and microstructural evidence from along the massif-ophiolite contact indicate at least two deformational episodes. Samples collected within the Chain Lakes massif near the contact contain similarly oriented lineations, but their fabrics, some S-C mylonitic, exhibit opposite asymmetries. In order to better constrain the kinematic history of the suture zone, and in particular ophiolite emplacement, we are in the process of using other structural evidence in combination with geochronology to unequivocally relate each generation of fabric development with tectonic events that drove the deformation.