Structural investigation of the Porpoise Cove area, northeastern Superior Province, northern Quebec.

摘要

The Porpoise cove area, in the northeastern Superior Province, northern Quebec, represents a rare example of Archean geology containing a previously unrecognized Eoarchean (∼3825 Ma) greenstone sequence (Nuvvuagittuq belt). This sequence consists of layers of amphibolite, garnet-bearing amphibolite, meta-conglomerate, and iron formations, in intrusive contact with surrounding Neoarchean tonalite and granodiorite (Boizard suite) intrusions (∼2750 Ma) and intruded by Neoarchean pegmatite dykes (∼2690 Ma). These extensive tonalites contain mafic xenoliths of similar composition to the Nuvvuagittuq greenstone sequence. A detailed small-scale outcrop study of the supracrustal sequence and adjacent tonalite with associated xenoliths indicates that both sites experienced at least six deformation phases, including a prominent syn-magmatic phase within the Boizard suite. (Abstract shortened by UMI.)