Late Paleozoic to Cenozoic Reconstruction of the Arctic: ABSTRACT

Abstract

The plate tectonic evolution of the Arctic is reassessed in the context of the known histories of the North Atlantic and North Pacific Oceans, and of the tectono-stratigraphic development of the lands around the Arctic Ocean. Computer map-drawing facilities were used to provide geometrical constraints on the reconstructions, which are presented in the form of eight palinspastic maps. Stratigraphic similarities among presently dispersed continental areas identify fragments of a former plate. Collision of this plate with the Euramerican plate was the cause of the Late Devonian Ellesmerian orogeny. In later Paleozoic time, the Siberian continent also joined Pangea by collision with the combined Barents and Euramerican plates along the Urals-Taymyr suture. The Mesozoic-Cenozoic history of the Arctic is concerned with the fragmentation and dispersal of the former Barents plate, as well as the accretion of new continental fragments from the Pacific. Of the major basins of the present-day Arctic Ocean, the Eurasia basin formed contemporaneously with the North Atlantic Ocean and is still spreading, while the earlier opening of the Canada basin was largely connected with events in the Pacific. The Canada basin formed by the separation of northern Alaska from the area now occupied by the Alpha Ridge. Initial rifting in the Late Jurassic was contemporaneous with the earliest major accretionary events in eastern Siberia and the northwestern Cordillera of North America. An Early to mid-Cretaceous age for the main phase of spreading is confirmed by the age-depth relationship for the floor of the Canada basin. After this time, the Canada basin formed part of the North Atlantic plate, and subsequent movements related to the opening of the orth Atlantic and Eurasia basins were taken up within Siberia and the Bering Sea area. The history of the latter is not yet clear for times earlier than the late Eocene--the earliest time for which it is possible to make a geometrically realistic reconstruction of that area. Earliest stages of spreading in the northern North Atlantic caused the initial separation of Greenland from North America. The Eurekan orogeny in the eastern Canadian Arctic is a local result of this spreading. Palinspastic restoration of the eastern Canadian Arctic Islands is required to fill the gap otherwise left in reconstruction of that area. The Eurasia basin opened contemporaneously with the Norwegian Sea and thus entirely postdates the Canada basin. Geometrical constraints suggest that the Makarov basin, between the Alpha and Lomonosov Ridges, formed during the Eocene. End_of_Article - Last_Page 679------------