Abstract

The Huron Claim pegmatite and members of the Shatford Lake group are a NYF-like granitic pegmatite population located amidst the dominant LCT-family pegmatites of the Winnipeg River pegmatite district, Manitoba. The age of intrusion of the Shatford Lake pegmatites was established by the U/Pb method using gadolinite-(Y) and gave a concordant 2656.1 ± 1.4 Ma age. A subsequent age-resetting event at ~2580 Ma was given by U/Pb analyses of uraninite from the Huron Claim pegmatite and is supported in some measure by Rb-Sr data from micas. Monazite-(Ce) and ferrocolumbite U/Pb analyses yielded ages between the gadolinite-(Y) and uraninite ages, indicating partial age-resetting of both minerals. A further resetting event is revealed by post-2580 Ma gains and losses in radiogenic Sr and Pb in feldspars. These NYF pegmatites are in close proximity to or cut by crustal-scale shear zones. Consequently, we interpret the ca. 2580 and post-2580 Ma overprints to indicate late-stage reactivation and fluid flow along these major structures.

You do not currently have access to this article.