Abstract

The Silurian System of the Canadian Arctic Islands, exposed in an area of more than 700 000 km 2 , contains three major stratigraphic-structural provinces: a southeastern and southern carbonate shelf, a central deep water basin (Hazen Basin/Foredeep) and a suspect terrane with North Atlantic affinities (Pearya) in northernmost Ellesmere Island. The shelf succession is divisible into five time-rock slices that are separated by extensive transgressive surfaces or sequence boundaries. The first, of Rhuddanian age, was deposited immediately after an important regression of latest Ordovician (fastigatus Zone) age. The platform was initially ramp-like and without reefs, and shelf-interior deposits were of mainly open marine aspect. Aeronian to Telychian carbonate shelf deposits, which constitute the second time slice, feature ramp-to-rimmed platform development with extensive shelf-interior and shelf margin stromatoporoid-coral reefs, particularly in North Greenland. The third slice, ranging in age from latest Telychian to early Ludfordian, demonstrates the continued development of the rimmed carbonate platform, but most shelf-edge reefs were formed by a unique coral-microbial consortium and shelf-interior deposits were of highly restricted marine aspect. The fourth slice, confined to the early Ludfordian, contains syntectonic clastic strata that indicate movements of the southern Boothia Uplift. The uplift was linked kinematically to the stresses in the coeval Caledonian Orogen and its structural-stratigraphic history in part resulted from basement anisotropies which developed during ?latest Proterozoic continental break-up. The fifth slice, which ranges in age from late Ludfordian to earliest Lochkovian, demonstrates movements of the entire Boothia Uplift. Coarse clastics sediments accumulated on the flanks of the uplift, while argillaceous sediments were deposited in the remaining parts of the shelf province. The deep water basin is divisible into a southeastern sedimentary subprovince that extends from northeast Greenland to Melville Island and a northwestern sedimentary-volcanic subprovince, exposed only in northern Ellesmere and Axel Heiberg islands. In the sedimentary subprovince, very slow sedimentation of radiolarian chert, mudrock and resedimented carbonates, that commenced in the late Early Cambrian, was followed by rapid flysch deposition during a part of Silurian and Devonian time. The flysch was derived mainly from the Caledonides east of North Greenland but also from northerly sources and prograded southwest. The diachronous basal contact of the flysch ascends in age from Telychian in North Greenland and Ellesmere Island to Eifelian in Melville Island; the top is Lochkovian to Eifelian. Silurian deposits in the remaining northern regions are strongly tectonized and relatively poorly dated. Pearya appears to have been accreted during an Ashgill to early Telychian interval characterized by unconformities and a variety of volcanic and syntectonic clastic deposits. In Ellesmere Island, the sedimentary-volcanic subprovince and adjacent parts of Pearya were overlapped by Caledonian-derived flysch in late Telychian to Gorstian time. These deep-water strata are disconformably overlain by shallow marine clastic and carbonate strata of Ludfordian age. In northern Axel Heiberg Island a volcanic arc and fore-arc assemblage of Telychian-Homerian age is unconformably overlain by nonmarine and shallow marine syntectonic siliciclastic strata of Early Devonian and (?) older age. Differences in structural style suggest an intervening orogeny, probably a collision that terminated the subduction regime.

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