Precambrian metamorphic and tectonic evolution of northern Baffin Island, Nunavut, Canada

The northern part of Baffin Island, in Nunavut, lies within the ca. 3.0-2.5 Ga Committee belt, characterized by episodic granitic plutonism and greens chist- to upper-amphibolite-facies belts of supracrustal rocks. Whereas the entire belt on Baffin Island was likely affected by ca. 2.7 Ga plutonism a nd associated metamorphism, there is also evidence of a high-grade event at ca. 2.55-2.5 Ga Evolution of the Baffin orogen in south-central Baffm Isla nd led to generation of theca. 1.86 Ga Cumberland Batholith, ca. 1.85-1.83 Ga northwest-directed thrusting of the Fore ford-and-thrust belt over the D exterity granulite belt (DGB), and variable structural and metamorphic rewo rking of the Committee belt on northern Baffin Island. Thermobarometric dat a for granulite-facies rocks in the western DGB indicate similar to 8.7 kba r paleopressure, interpreted to have been achieved in continental crust thi ckened by thrust imbrication. Paleopressure decreases gradually northward f rom the western DGB to <4 kbar, but decreases sharply south of the Isortoq fault zone (IF), which approximates the southern boundary of the DGB. Combi ned thermobarometric and structural constraints suggest that the IF represe nts an important crustal-scale structure involved in both NW-directed thrus ting and tectonic loading of the DGB, as well as subsequent extensional unr oofing of the DGB. Southwest-directed thrusting in the ca. 1.825-1.81 Ga No rtheast Baffin thrust belt (NBTB) is interpreted to have produced similar t ectonic thickening and similar to 10.5 kbar pressures along most of the len gth of this belt on northern Baffin Island, including the eastern part of t he DGB. The similar to 6-8 kbar Archean Bylot Batholith represents a higher structural level that may have contributed to tectonic loading of adjacent high-pressure rocks in the NBTB.