Pre-Quaternary History of North Greenland1
Published:January 01, 1973
In North Greenland, the crystalline basement is unconformably overlain by a late Precambrian to early Paleozoic sedimentary sequence. The Inuiteq So Formation, containing conspicuous basic intrusions, is at least 1,000 m.y. old; the youngest dated strata are Middle to Late Silurian. A southern platform sequence of un-metamorphosed homoclinal strata passes northward into the east-west-trending North Greenland fold belt, in which mainly Cambrian to Silurian rocks are exposed. In western North Greenland, the upper part of the platform section is a reef complex showing facies changes between reef carbonate rocks and offreef argillaceous rocks.
In eastern Peary Land, folded lower Paleozoic beds underlie a cover of less severely deformed Pennsyl-vanian, Permian, Triassic, and Cretaceous-Tertiary strata which show the effects of Tertiary deformation. In northern Peary Land, the folded metasedimentary units have been transported northward over the Kap Washington Group of bedded lavas and tuffs along the Kap Cannon thrust. These volcanic rocks have given a minimum K-Ar age of 35 m.y.
In Peary Land, where the widest section of the fold belt is exposed, five tecfonic-metamorphic zones are recognized; the deformational and metamorphic effects increase northward. The metasedimentary rocks have been subjected to a complex late Phanerozoic-Paleozoic tectonic and metamorphic history. Paleozoic orogenesis (Late Silurian to Late Devonian) involved polyphase deformation which produced three essentially coaxial fold phases. Rocks affected by these three phases of folding are overturned northward toward the highest grade rocks, which in northern Peary Land contain amphibolite-facies assemblages. Cretaceous K-Ar ages of the metamorphic rocks suggest a subsequent thermal event of regional importance. Tertiary orogenesis is indicated by evidence of folding, thrusting, and regional faulting, and of mylonitization and low-grade metamorphism associated with the Kap Cannon thrust.
Figures & Tables
Following the discovery of Prudhoe Bay oil field in 1968, much attention was turned to the Arctic in the search for giant hydrocarbon accumulations. The Soviets had already proved giant reserves in their West Siberian Basin, and exploration was moving ahead quickly in the Canadian Arctic. Plans were drawn up for an AAPG Symposium on Arctic Geology and held in February 1971. Papers were selected from the Symposium for this publication and cover seven topical groupings: Regional Arctic Geology of Canada, Regional Arctic Geology of the Nordic Countries, Regional Arctic Geology of the USSR, Regional Arctic Geology of Alaska, Comparisons in the North Atlantic Borders, Evolution of the Arctic Ocean Basin, and Economics of Petroleum Exploration and Production in the Arctic.