Geochemistry, Nd, Pb and Sr Isotope Systematics, and U-Pb zircon ages of the Neoarchean Bad Vermilion Lake Greenstone Belt and Spatially Associated Granitic rocks, Western Superior Province, Canada

摘要: Abstract The ca. 2720 Ma Neoarchean Bad Vermilion Lake (BVL) greenstone belt, in the western Superior Province, Canada, is composed of a suite tholeiitic to calc-alkaline basalts rhyolites, volcaniclastic rocks, gabbros, and Timiskaming-type siliciclastic sedimentary rocks. belt was intruded by granitic underwent greenschist facies metamorphism intense deformation, resulting mobilization many elements (e.g., Rb, Ba, Sr, K, U, Pb). high-field strength element rare earth systematics volcanic gabbros are consistent with subduction zone geochemical signatures, suggesting that BVL formed magmatic arc setting. On basis lithological associations trace systematics, defined as fragment subduction-related ophiolite. Three rhyolite samples from have yielded 2722 ± 18 Ma, 2706 ± 13 Ma 2710 ± 28 Ma U–Pb zircon ages, representing approximate age volcanism study area development between Wabigoon terrane north Wawa-Abitibi south. intrusion 2664 ± 15 Ma late- post-tectonic, potassic Ottertail granite marks end tectonic accretion area. Both rocks display large ranges Nd (143Nd/144Nd = 0.511600–0.512849; eNd (2720 Ma) = + 0.8 to + 4.0), Pb (206Pb/204Pb = 13.80–60.67) Sr (87Sr/86Sr = 0.701481–1.01154) isotopic compositions, these isotope systems were variably affected post-magmatic mobility. Neither Sm–Nd (2921 ± 200 Ma) nor Rb–Sr (2130 ± 610 Ma) system has reliable regression (isochron) reflecting open-system behavior during metamorphism. Despite uncertainties, Pb–Pb ages all rock types (2661 ± 60 Ma), (2725 ± 83 Ma) agree most robust among three systems.