Laurentian margin evolution and the Caledonian Orogeny : a template for Scotland and East Greenland

The orthotectonic Scottish Caledonides constitute only a small fragment of the Neoproterozoic to Paleozoic margin of Laurentia, albeit one which lies at a prominent bend in that margin. Sequences exposed in the Scottish outcrop include Mesoproterozoic, Neoproterozoic and Cambro-Ordovician strata which record sedimentation, volcanism and deformation related to the latter stages of the amalgamation of Rodinia, the subsequent breakout of Laurentia, and growth of the Iapetus Ocean. Metamorphic and tectonic overprints then record the destruction of that ocean through Ordovician arc accretion and mid-to-late Silurian collision of Laurentia, Baltica and Avalonia with the final closure of Iapetus by end-Silurian time. New isotopic data and recent advances in the understanding of the late Mesoproterozoic (Stenian) to Cambro-Ordovician stratigraphical framework now better constrain the sequence and timing of events across the ‘Scottish Corner’ and invite a dynamic comparison with the current research into the East Greenland Caledonides summarised in this volume. Although many broad similarities exist, the comparisons described here reveal for the first time a number of significant contrasts in the spatial arrangement of depocentres, location of rifting, patterns and timing of magmatism, metamorphism and contractional deformation. This expanded understanding of the late Neoproterozoic evolution of these adjacent sectors of Laurentia provides an important basis for reconstructions of the subsequent lower Paleozoic Caledonian orogenic evolution of the present North Atlantic region