Age and Chemostratigraphy of the Finlayson Lake District, Yukon: Implications for Volcanogenic Massive Sulfide (VMS) Mineralization and Tectonics along the Western Laurentian Continental Margin

Abstract The Yukon-Tanana terrane in the Finlayson Lake district, Yukon, represents one of first arc–back-arc systems that formed adjacent to Laurentian continental margin mid-Paleozoic. Back-arc rocks contain many large and high-grade volcanogenic massive sulfide (VMS) deposits. This study integrates U-Pb zircon geochronology, lithogeochemistry, Hf-Nd isotopes establish precise controls on tectonomagmatic activity western Late Devonian Early Mississippian. High-precision chemical abrasion- (CA-) ID-TIMS geochronology defines coeval arc (ca. 363.1 348 Ma) back-arc 363.3 355.0 magmatism district intruded crust affinity (e.g., Snowcap assemblage). Mafic felsic display geochemical isotopic characteristics are consistent with being from mixtures depleted asthenosphere enriched lithospheric mantle sources. These melts variably entrained via high-temperature crustal melting due basaltic underplating. occurs at specific time periods coinciding VMS deposits supports previous genetic models for mineralization suggest elevated heat flow hydrothermal circulation were regional-scale rift-related rather than local subvolcanic intrusions. short timescales transient nature events rapid complex subduction initiation oceanic fragments facilitated compression, extension, regions. We thus reevaluate presently accepted tectonostratigraphic framework revised interpretations shed light depositional environments a possible broader association ca. 358 Ma Antler Orogeny. Results this have implications incipient tectonics, magmatism, along other orogenic belts globally.