DETRITAL ZIRCONS IN THE PALEOZOIC SUCCESSION OF NOVAYA ZEMLYA -- EVIDENCE OF GRENVILLE - SVECONORWEGIAN BASEMENT IN THE CALEDONIAN HINTERLAND OF THE HIGH ARCTIC

The Caledonide, Timanide and Uralide orogens define the northwestern, northeastern and eastern margins of the Fennoscandian Shield. They developed successively along the flanks of the paleocontinent Baltica from the late Neoproterozoic (Timanides) to the early-mid Paleozoic (Caledonides) and late Paleozoic to earliest Mesozoic (Uralides). Evidence of earlier, Sveconorwegian (Grenvillian) orogeny outcrops only in the southwestern part of the Shield. These four orogens have have igneous and metamorphic signatures that characterize their evolution, signatures that are readily recognizable in the detrital zircons of younger sedimentary rocks of appropriate age. A detrital zircon investigation of the Paleozoic strata of the Novaya Zemlya archaepelago -- the northern prolongation of the Uralides into the high Arctic, is on-going. It demonstrates not only that the unconformably underlying Timanide basement provided an important source for all the Paleozoic strata, but also that, during the Silurian and Devonian, provenance terrains were dominated by Sveconorwegian (perhaps Grenvillian) complexes. Facies changes in the Siluro-Devonian (shallowing of the marine strata from southeast to northwest and fluvial intercalations in the latter) and other evidence of proximity to the southeastern thrust front of the high Arctic Caledonides, indicates that these Mesoproterozoic to earliest Neoproterozoic rocks were probably exposed within the hinterland of the Barents Shelf Caledonides. This and other evidence from the high Arctic continental shelves favours the interpretation that the Grenville-Sveconorwegian orogen continued northwards from type areas in southeastern Canada and southwestern Scandinavia far into the Arctic, requiring fundamental revision of recent reconstructions (ca 900 Ma) of the Rodinia supercontinent, and the character of Caledonian orogeny.