Distribution, facies, ages, and proposed tectonic associations of regionally metamorphosed rocks in Southwestern Alaska and the Alaska Peninsula

Cynthia Dusel-Bacon; Elizabeth O. Doyle; Stephen E. Box

doi:10.3133/pp1497b

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Distribution, facies, ages, and proposed tectonic associations of regionally metamorphosed rocks in Southwestern Alaska and the Alaska Peninsula

Cynthia Dusel-Bacon·Elizabeth O. Doyle·Stephen E. Box

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Abstract

The oldest dated metamorphic sequence in Alaska, the fault-bounded Kilbuck Terrane, consists of continental rocks that were metamorphosed under amphibolite-facies conditions during early Proterozoic (1.77 Ga) time. Proterozoic or early Paleozoic metamorphic ages are also possible for greenschist- and amphibolite-facies continental rocks in interior Alaska (Ruby and Nixon Fork terranes). Medium-grade metamorphism on the Alaska Peninsula accompanied intrusion of a Jurassic arc. North of Bristol Bay, low-grade, locally high-pressure Mesozoic metamorphism is attributed to the progressive underthrusting of a subduction complex beneath an oceanic arc followed by underthrusting of the Kilbuck Terrane beneath the subduction complex.

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Source-reported bounding extent: 53.94315470224928° to 64.03374392176401° latitude; -167.76123046875° to -153.017578125° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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Cynthia Dusel-Bacon, Elizabeth O. Doyle, Stephen E. Box. 1996. Distribution, facies, ages, and proposed tectonic associations of regionally metamorphosed rocks in Southwestern Alaska and the Alaska Peninsula. https://doi.org/10.3133/pp1497b

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