ABSTRACT

It has been established previously that a narrow zone in the central southern part of the Canadian Arctic Archipelago composed of Boothia Arch and Cornwallis fold belt has been affected by Siluro-Devonian (Caledonian s.s.) movements that involved the crystalline Precambrian basement. Recently an unconformity of low to moderate angular discordance between Middle Silurian and Lower or Middle Devonian (possibly Uppermost Silurian) strata has been discovered in northernmost Axel Heiberg Island, some 800 miles north of the southern extremity of the Boothia Arch. In both areas there is evidence of Middle and Late Silurian intermittent tectonism and, in the north, of keratophyric volcanism. Between the northern end of the Cornwallis fold belt and northernmost Axel Heiberg Island the Lower Paleozoic strata are concealed by younger deposits that were deformed in Tertiary time. The parallelism of Tertiary and Caledonian trends suggests that this area is also underlain by Caledonian structures which appear to have impressed their grain on all subsequent deformations. The influence, however, of pre-Silurian structures of similar orientation exposed in northernmost Axel Heiberg Island cannot be assessed. The belt of Caledonian movements cuts across parts of the Franklinian eugeosyncline and miogeosyncline into Arctic Lowlands and Canadian Shield and trends at high angles to several fold belts. Within the Polar regions, the Caledonian disturbance of the Canadian Arctic Archipelago coincides approximately with geosynclinal orogenies in eastern Greenland, Spitsbergen and possibly northwestern Scandinavia, and with platform movements in parts of northern Russia and Siberia.