GEOCHRONOLOGICAL CONSTRAINTS ON LATE ARCHEAN MAGMATISM DEFORMATION AND GOLD QUARTZ VEIN MINERALIZATION IN THE NORTHWESTERN ANIALIK RIVER GREENSTONE-BELT AND IGNEOUS COMPLEX, SLAVE PROVINCE, NWT

Three phases of the Anialik River igneous complex (ARIC) give U-Pb zir con ages in the range approximately 2705-2683 Ma, and three units from the adjacent northwestern Anialik River greenstone belt (ARGB) give c a. 2678 Ma ages. Titanite from unsheared ARIC rocks crystallized durin g localized metamorphism and deuteric alteration between 2693 and 2683 Ma. Hydrothermal titanite in wall rocks to gold-mineralized shear zon es crystallized during early shear zone development (2670 +/- 1 Ma) an d was subsequently locally altered to rutile, with gold occuring withi n the rutile-bearing assemblage. Unaltered second-generation hydrother mal titanite, overgrowing the rutile assemblage, crystallized during l ater brittle-ductile movement (2656 +/- 2 Ma) and provides a minimum a ge for gold mineralization. Relatively high Pb-207/Pb-204 ratios of Pb in gold-associated galena suggest that it was partly derived from sig nificantly older crustal material, possibly underlying the igneous com plex and greenstone belt. This interpretation is consistent with other evidence for the existence of > 3.0 Ga crustal rocks to the west of t he study area. A late crosscutting granite gives an age of 2601(-4)+6 Ma and is therefore part of the Pan-Slave tectono-thermal event. These results, and other data for the Slave Province, indicate temporal var iations in the development and deformation of predeformational greenst one belts. The new ages show that regional deformation and metamorphis m in the northwestern Slave Province followed shortly after major magm atism, and that gold mineralization might have occurred during the lat e Archean accretion of the greenstone belt and igneous complex to an o lder crustal domain to the west.