GEOLOGY, GEOCHEMISTRY, AND GEOCHRONOLOGY OF THE CENTRAL GIANTS RANGE BATHOLITH, NORTHEASTERN MINNESOTA

The Giants Range batholith is a large composite granitoid body that in trudes deformed supracrustal rocks in the western part of the Wawa Sub province of the Archean Superior Province. Peak fabric development in the supracrustal rocks coincides with D2 deformation, the product of r egional transpression across the southern Superior Province. U - Pb zi rcon ages on two phases of the Giants Range batholith bracket D2 defor mation to an interval between 2685 and 2669 Ma. Two well-exposed compo nents of the central part of the Giants Range batholith are the pre- t o syn-D2 Britt granodiorite, which contains a linear D2 metamorphic fa bric, and the syn- to post-D2 Shannon Lake granite, which cuts deforma tion fabrics in the Britt granodiorite and the supracrustal rocks. Geo chemical discrimination plots imply emplacement of the Britt granodior ite in an arc environment and the Shannon Lake granite in a collision setting. Zircons yield U - Pb ages of 2681 +/- 4 and 2685 +/- 4 Ma for the Britt granodiorite and 2674 +/- 5 and 2674 +/- 27 Ma for the Shan non Lake granite. Timing of D2 deformation near the Giants Range batho lith corresponds well with similar rocks exposed along strike 170 km t o the east near Shebandowan Lake, Ontario, where the end of D2 deforma tion has been bracketed between 2692 and 2681 Ma. The slightly younger ages for D2 deformation in Minnesota reflect later volcanic-arc devel opment and associated plutonism than at Shebandowan Lake, possibly due to oblique convergence along a westward-migrating tectonic front.