The Grenville-Sveconorwegian orogen in the high Arctic

Throughout the high Arctic, from northern Canada (Pearya) to eastern Greenland, Svalbard, Franz Josef Land, Novaya Zemlya, Taimyr and Severnaya Zemlya and, at lower Arctic latitudes, in the Urals and the Scandinavian Caledonides, there is evidence of the Grenville-Sveconorwegian Orogen. The latest orogenic phase (c. 950 Ma) is well exposed in the Arctic, but only minor Mesoproterozoic fragments of this orogen occur on land. However, detrital zircons in Neoproterozoic and Palaeozoic successions provide unambiguous Mesoproterozoic to earliest Neoproterozoic (c. 950 Ma) signatures. This evidence strongly suggests that the Grenville-Sveconorwegian Orogen continues northwards from type areas in southeastern Canada and southwestern Scandinavia, via the North Atlantic margins to the high Arctic continental shelves. The widespread distribution of late Mesoproterozoic detrital zircons far to the north of the Grenville-Sveconorwegian type areas is usually explained in terms of long-distance transport (thousands of kilometres) of either sediments by river systems from source to sink, or of slices of lithosphere (terranes) moved on major transcurrent faults. Both of these interpretations involve much greater complexity than the hypothesis favoured here, the former involving recycling of the zircons from the strata of initial deposition into those of their final residence and the latter requiring a diversity of microcontinents. Neither explains either the fragmentary evidence for the presence of Grenville-Sveconorwegian terranes in the high Arctic, or the composition of the basement of the continental shelves. The presence of the Grenville-Sveconorwegian Orogen in the Arctic, mainly within the hinterland and margins of the Caledonides and Timanides, has profound implications not only for the reconstructions of the Rodinia supercontinent in early Neoproterozoic time, but also the origin of these Neoproterozoic and Palaeozoic mountain belts.