Caledonian granites of western and central Nordaustlandet, northeast Svalbard

The Nordaustlandet Terrane of northeast Svalbard is the easternmost of the Caledonian terranes of the Svalbard archipelago. Here, a Grenville-age basement is overlain by Neoproterozoic to Early Palaeozoic platform sediments, and intruded by Caledonian granites. These include the Nordkapp, Rijpfjorden and Winsnesbreen granites of western and central Nordaustlandet, which are peraluminous, crustal anatectic two-mica granites, formed in a Caledonian late- to post-tectonic setting. Sm-Nd isotope characteristics show them to have formed largely by anatexis of the Grenvillian crust, which is supported by the presence of abundant Grenville-age and earlier Mesoproterozoic inherited zircons. U-Pb dating of new-formed zircon overgrowths and whole crystals using the NORDSIM ion microprobe, as well as conventional U-Pb dating of monazite, and single zircon and monazite Pb-evaporation dating, yield ages of 440-410 Ma, indicating formation during the main, Silurian to early Devonian stage of the Caledonian Orogeny. These results show the importance of applying single crystal Pb-evaporation and ion microprobe spot analyses for the dating of complex zircons in crustal anatectic granites containing abundant inherited material.