Abstract

U–Pb zircon dating of the southwest lobe of the Havre-Saint-Pierre anorthosite intrusion indicates that it is 1062 ± 4 Ma old. Parallelism of magmatic and solid-state foliations with the adjacent Abbé–Huard lineament suggest that anorthosite parental magmas rose up this shear zone, which was active at that time. The age of igneous crystallization is much younger than that of a spatially associated mangerite intrusion, but accords with age data from other granitoid intrusions elsewhere in the Grenville Province. Evidence points to a widespread 1.09–1.05 Ga magmatic event that included massif anorthosite intrusions. This magmatic event coincided with late stage convergent tectonics in the southwestern Grenville Province.

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