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The AAPG/Datapages Combined Publications Database
AAPG Bulletin
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Rocks of northern Alaska may have had tectonic continuity with rocks of central Alaska. The present syntaxis would have formed along with those at the ends of the Brooks Range in response to right-lateral drift between the Arctic and outboard plates. The Cretaceous Koyukuk basin is interpreted to have been "crunched" between the northwestern and southeastern syntaxes.
Palinspastic data suggest that (1) the Fairbanks area was once south of the Prince Rupert area, (2) the Arctic Alaska basin separated the Ellesmerian-Antler orogene from the proto-Pacific ocean, and (3) Cretaceous fore-shortening against this continental edge resulted in construction of the Brooks Range foldbelt and the flanking Koyukuk and Colville basins. Space is sufficient to accommodate later accretion of Wrangellia and other lithospheric "crumbs" to Alaska.
This surmise, which could be tested by analysis of paleomagnetism, accommodates more observations that the Patton-Carey alternative of rifting followed by partial closing of the Koyukuk basin sphenochasm. It would also explain or clarify the following: (1) the 135° acuity (instead of natural, curvilinear trends) for belts of "ophiolite," of glaucophane, of metamorphism, of plutonism, etc; (2) the thrust-superpositions of coeval sequences along the upper Yukon; (3) the absence of tectonic provenances for Cretaceous orogenic deposition in central Alaska; and (4) the young igneous detritus on the west edge of the MacKenzie delta, more than 100 km from the closest source.
If validated, this hypothesis would greatly reduce estimates of the hydrocarbon potential of central Alaska, but would predict extensions of Brooks Range copper and lead-zinc provinces southwestward across the Yukon River and eastward beyond Fairbanks.
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