TESTING ALTERNATIVE MODALS OF ANORTHOSITE EMPLACEMENT IN THE ADIRONDACK MOUNTAINS

The Marcy Massif is a major component of the bedrock geology of the high peaks region of the Adirondacks. The Massif is composed anorthosite and surrounded by a gabbroic gneiss known as the border facies. The nature of the deformation recorded by the border facies gneiss is debated. It may be a primary magmatic feature related to diapiric ascent, a tectonic feature recording post emplacement contractional orogenesis, or record exhumation along the Marcy Massif detachment zone. Here we present a strain analysis of a vertical transect through the border facies border facies at Cooper Kiln landslide in the Northern section of the Massif. Five oriented rock samples were taken from different structural levels and cut on orthogonal surfaces parallel to X, Y, and Z principal strain axes and digitized using EllipseFit. Preliminary results indicate that flattening strain dominates at lower structural levels and progresses into constriction near the top of the slide.