Apatite fission-track dating of the Cowichan fold and thrust system, southern Vancouver Island, British Columbia

Autor:	D. S. Miller, N. W. D. Massey, L. D. Currie, M. K. Roden-Tice, T. D. J. England
Rok vydání:	1997
Předmět:	Paleontology visual_art visual_art.visual_art_medium General Earth and Planetary Sciences Sedimentary rock Thrust fault Fold (geology) Fission track dating Closure temperature Geology Apatite Cretaceous Terrane
Zdroj:	Canadian Journal of Earth Sciences. 34:635-645
ISSN:	1480-3313 0008-4077
DOI:	10.1139/e17-050
Popis:	The Cowichan fold and thrust system on southern Vancouver Island comprises a linked system of folds and thrust faults in crystalline and sedimentary rocks of the Wrangellia terrane and its sedimentary cover, the Upper Cretaceous Nanaimo Group, and Upper Paleocene to Lower Eocene sandstones of the Chuckanut Formation. Apatite fission-track analysis indicates that cooling below the closure temperature of fission-track retention in apatite (100 ± 20 °C) for both the Island Plutonic Suite from the Wrangellian basement and the Nanaimo Group occurred at ~ 50–40 Ma (Middle Eocene). Thrusting is interpreted to have occurred immediately prior to this time in the Middle Eocene, but after post-Cretaceous regional burial of the Turonian to Maastrichtian Nanaimo Group and deposition of Upper Paleocene and Lower Eocene sandstones, which are involved in the deformation. These timing constraints support the hypothesized temporal linkage between contraction and uplift of Wrangellia during the Middle Eocene and continued margin-normal contraction of the Pacific Rim terrane (± the Crescent terrane) at ~ 45 Ma.
Databáze:	OpenAIRE
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