Volcanic rocks which have piled up more or less continuously since the middle Tertiary virtually compose the Iceland landmass. The rocks can be divided into four major formations: Tertiary Plateau Basalt formation; lower Pleistocene Grey Basalt formation; upper Pleistocene Palagonite formation; and Weichselian till, Holocene sediments, and volcanic rocks. Basaltic lava flows make up the largest percent of the Tertiary Plateau Basalt formation. The Pleistocene formations contain a greater variety of rock facies and notably more subglacial hyalo-clastic sediments, fluvial and marine sediments, and tillites. The rocks contain records of sudden climatic changes—e.g., about 3 m.y. ago (at the beginning of the Pleistocene). Holocene volcanism in Iceland has produced mostly basaltic lavas, but also intermediate and acidic rocks. Volcanic fissures and faults charaterize the Neovolcanic zone, which is believed to be related to the position of Iceland on the Mid-Atlantic Ridge.
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.