Contributions to the tectonic history of the Innuitian Province, Arctic Canada

Abstract

The Innuitian Tectonic Province contains the record of a Phanerozoic mobile belt in northern Greenland and the Canadian Arctic Archipelago. Two fundamentally different phases in its development were separated by the Devonian–Carboniferous Ellesmerian Orogeny. The first contribution focuses on the early Paleozoic history of a key area, the second summarizes the Carboniferous to Cenozoic history of most of the Canadian part of the province.(1) The early Paleozoic architecture of the mobile belt is apparent only in Ellesmere Island, where exposures extend from the Canadian Shield through Arctic Platform and Franklinian basin into the Pearya orogenic welt. The Franklinian basin comprised the deep but ensulic Hazen Trough and two unstable shelves bordering it on the northwest and southeast. The northwestern shelf was a site of felsic to intermediate volcanism, mainly in the Ordovician Period. Pearya, a site of granitic plutonism in the Devonian Period, supplied much of the clastic basin fill. Its core consisted of a metamorphic complex, about 1.0 Ga old, exposed in basement uplifts in nor thernmost Ellesmere Island. Both basin and welt essentially formed part of the North American Plate, although rifting, evident from mafic and ultramafic intrusions, probably occurred in Early Devonian (or latest Silurian) time. The history of this part of the province is tentatively interpreted as response to the opening and closure of an ocean, connected with lapetus, that separated northern Ellesmere Island and Greenland from the sialic crust of the present Lomonosov Ridge and Barents Shelf. The Lomonosov Ridge still seems to be attached to the shelf off northeasternmost Ellesmere Island.(2) Deep subsidence and filling of Sverdrup Basin dominated the Innuitian region from Early Carboniferous through Late Cretaceous time. Large halokinetic diapirs and mafic dikes and sills intruded axial parts of the basin succession through Mesozoic time. Steep faults along the northwestern margin of the basin are Middle Cretaceous and older. Part of the northwestern rim of Sverdrup Basin sagged in latest Cretaceous time, becomingpart of the Arctic continental terrace. In the Late Cretaceous and early Tertiary a system of large grabens developed through the southern part of the Innuitian region, linking Canada Basin with Baffin Bay; about the same time, uplift formed some large arches in the northeastern part of the region. Middle Eocene and older rocks were laterally compressed by a phase of pre-Miocene folding and faulting. Some uplift took place in Oligocene or Miocene time on Axel Heiberg Island. The distribution of recent earth quakes does not indicate the presence of modern active plate margins.

Caledonian terranes in Svalbard

“…8). A diamictite has locally been described and has been correlated with other Vendian tilloids (Trettin and Balkwill, 1979). A silicic tuff in the upper part of the succession (Milne Fiord Assemblage: Fig.…”

“…7). A large stratigraphic hiatus occurs from the Late Devonian to the Mississippian and correlates with the Ellesmerian Orogeny (Trettin and Balkwill, 1979;Christie, 1979;Dawes and Peel, 1981). Trettin (1987) suggested that juxtaposition of the Pearyan terrane and the Hazen basin occurred in the Ludlow.…”

Tectonic map of the Ellesmerian and Eurekan deformation belts on Svalbard, North Greenland, and the Queen Elizabeth Islands (Canadian Arctic)

“…[31,53,55,56,66,67,69]). The dominant structures are large-scale anticlines and synclines [41,53], which are exposed on Melville Island, Bathurst Island, and Ellesmere Island.…”

Crustal structure of the Canadian polar margin: results of the 1985 seismic refraction survey

“…The regional geology of the Arctic Islands has been established during the last 30 years by the Geological Survey of Canada (Thorsteinsson and Tozer 1970;Trettin and Balkwill 1979;Trettin, in press). Three tectono-stratigraphic sequences, separated by major unconformities, are mapped on the land areas adjacent to the northern portion of the polar continental shelf (Fig.…”