Northern Alaska Tectonics

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Geology of Northern Alaska

Moore, T.E., Wallace, W.K., Bird, K.J., Karl, S.M., Mull, C.G., and Dillon, J.T. (1994). Geology of northern Alaska, in Plafker, G., and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America, The Geology of North America, G-1.

Moore et al describes the overall geologic environment of northern Alaska. The authors explain that this region of Alaska is particularly unique in that it lies entirely north of the Arctic Circle and it is the most coherent stratigraphy in Alaska. The region includes one of the major mountain ranges in Alaska, the Brooks Range, as well as some of the most important economic resources and reserves in the United States.

This region is composed of varying sizes of plutons, batholiths and sedimentary rocks. Two major terranes encompass the region, the Arctic Alaska terrane and the Angayucham terrane as well as their associated subterranes as separated by faulting. The Arctic Alaska terrane is of Proterozoic to Cenozoic in age and underlies all of the Northern Slope and portions of the Brooks Range. Sea-floor spreading events in the Canada basin border the terrane to the north. The Arctic Alaska terrane extends eastward into Canada and is expected to extend westward under the Chuckchi Sea and portions of the Russian Far East. To the south, the terrane dips under the Angayucham terrane at the Kobuk suture and perhaps underlies areas of the Koyukuk basin. The Angayucham terrane is approximately 5-10 km thick (relatively thin), encompassing the greenstone belts of the south Brooks range and consists of mafic, ultramafic and marine sediments aging from the Devonian to the Jurassic. The take home message about the Angayucham terrane is that it potentially was a part of a large thrust sheet of oceanic rocks which took over the Arctic Alaska terrane during the Jurassic and Cretaceous time period.

As mentioned above, the stratigraphy of the region is composed mainly of marine...
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