Major and trace element geochemistry and genesis of supracrustal rocks of the North Spirit Lake Greenstone belt, NW Ontario, Canada

There is about a 300 Ma interval between Unit 1 volcanism at approximately 3.1 Ga, and igneous activity represented by the Bijou Point Complex which intrude rocks of Unit 3 at about 2.7 Ga. The basal volcanic rocks resemble MORBs whereas the young volcanic rocks are potassic and of calc-alkaline affinity. Although the rocks of the two basal units appear to have formed in or near a spreading center, the rocks of Unit 3 likely were produced in a subduction environment such as those found in island arcs or some continental margin settings. Together, the three units resemble products of a Wilson Cycle, operating between 3.1 and 2.7 Ga, with the calc-alkaline Bijou Point Igneous Complex representing terminal volcanism. Proof or rejection of this hypothesis requires additional detailed mapping, geochemical and geochronological investigations.