Zircon age depth-profiling sheds light on the early Caledonian evolution of the Seve Nappe Complex in west-central Jämtland

The Scandinavian Caledonides comprise nappe stacks of far-travelled allochthons that record closure the Iapetus Ocean and subsequent continental collision Baltica Laurentia. Seve Nappe Complex (SNC) includes relics outermost Baltoscandian passive margin were subducted to mantle depths. earliest deep subduction events has been dated ca. 500–480 Ma. Evidence this event reported from northern exposures SNC. Farther south in central southern segments SNC, (ultra)high-pressure rocks have yielded younger ages range 470–440 This study provides first early Caledonian evidence obtained by depth profiling zircon grains extracted Tväråklumparna microdiamond-bearing gneiss. These preserve eclogite facies overgrowths crystallized at 482.6 ± 3.8 A second, chemically-distinct overgrowth records granulite metamorphism 439.3 3.6 Ma, which corroborates previous geochronological for time. Based on these results, we propose entire outer was late Cambrian Ordovician, but may be almost entirely eradicated vast majority lithologies pervasive Ordovician Silurian metamorphism. • First SNC Jämtland. –U-Pb dating Two two high grade metamorphic events. Zircon depth-profiling applied polymetamorphic rock.