PETROLOGY AND STRUCTURE OF THE CENTRAL METASEDIMENTARY BELT BOUNDARY THRUST ZONE AND ITS HANGING WALL, GRENVILLE PROVINCE, ONTARIO

摘要

INTRODUCTION The southern Grenville Province in Ontario (Fig. 1) exposes metasedimentary, metavolcanic, and meta-plutonic rocks of the 1.3-1.2 Ga Central Metasedimentary Belt (CMB) sitting on top of orthogneiss-dominated 1.7-1.4 Ga rocks of the Central Gneiss Belt (CGB, Easton 1992). The boundary between these tectonic belts is the Central Metasedimentary Belt boundary thrust zone (CMBbtz; Fig. 2 and 3): a region of annealed, heterogeneously deformed mylonitic tectonites and marble melange tectonites surrounding dismembered metaplutonic thrust sheets (Hanmer, 1988; Hanmer and McEachern, 1992). The provenance of these thrust sheets and dismembered blocks (i.e. if they originate from the CGB, CMB, or elsewhere) is generally unclear.