⁴⁰Ar/³⁹Ar mineral age record in NE Greenland: Implications for tectonic evolution of the North Atlantic Caledonides

⁴⁰Ar/³⁹Ar mineral ages have been determined from basement gneisses and cover sequences exposed in the Caledonides of NE Greenland. These range between c. 438 Ma and c. 370 Ma. They are interpreted as dating cooling following polyphase Caledonian metamorphism which completely reset argon systems within the (early Proterozoic) basement gneisses. The ⁴⁰Ar/³⁹Ar results indicate that thrust-related regional deformation and metamorphism in NE Greenland continued into the early Devonian. This contrasts with Scandinavia, where nappe stacking was largely completed by the early-mid-Silurian and was followed by regional extension and tectonic unroofing in the late Silurian-mid-Devonian. -Authors