I. INTRODUCTIONA significant portion of New England formed as a result of an accretionary orogen. Southeastern New England is characterized by a series of terranes that accumulated into the Laurentian supercontinent during the Silurian and Devonian. The Gander, Nashoba, Avalon, and Meguma Terranes occur from west to east in eastern Massachusetts and are all of Gondwanan origin. Their modern juxtaposition suggests that Gondwana's marginal microcontinents collided sequentially from west to east, expanding the Laurentian continent with each respective collision. As each successive plate collided, an intermediate subduction zone died and a new one was created to the east. The oblique collision of the Avalon Terrane with Laurentia followed the accretion of the Gander and Nashoba Terranes and preceded the accretion of Meguma. The collision was marked by uplift, mylonitic metamorphism, and Nashoba calc-alkaline plutonism as the Iapetus Ocean subducted beneath the Nashoba and the Avalon eventually collided obliquely with the continental margin. The area composed of the Gander, Nashoba, Avalon, and Meguma Terranes has been extensively studied for many years. However, it has only been recently that terranes have been recognized as distinct geological entities with unique tectonic histories, so there is still much debate regarding the tectonic pattern that brought these terranes together (Hon et al., 2007). This paper will address the geology of peri-Gondwanan terranes and propose a potential tectonic model for orogenic accretionary events. It will also focus primarily on the juxtaposition between Nashoba and Avalon Terranes.II. TECTONIC SETTING Global tectonicsThe most recent complete cycle of the supercontinent......middle of paper......JC (2004) Mylonites and brittle shear zones along the western edge of the Avalon Terrane west of Boston, NEIGC Field Trip Guide.Marshak, S. (2009) Essentials of Geology, 3rd ed. New York: W. W. Norton & Company, chap. 11, page. 298-320.Skehan, J.W., Rast, N., Kohut, E., Hepburn, J.C. and Grimes, S.W. (1998) Precambrian and Paleozoic mylonites of the Boston Avalon, NEIGC Field Trip Guide.Stroud, M.M., Markwort, R.J. and Hepburn , J.C. (2009) Refining Temporal Constraints on Metamorphism in the Nashoba Terrane, Southeastern New England, Through Monazite Dating. Lithosphere, vol. 1, page. 337-342. Van Staal, C.R., Whalen, J.B., Valverde-Vaquero, P., Zagorevski, A. and Rogers, N. (2009) Pre-Carboniferous, Episodic Accretion-Related, Orogenesis along the Laurentian margin of northern Appalachia. Geological Society, London, Special Publications, vol. 327, page. 271-316.