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Pelitic and quartzose schist of the Alaska Range

Unit symbol: Pzarqm
Age range Devonian or older (541 to 358.9 Ma)
Lithology: Metamorphic
Group name: Schist and phyllite of the Alaska Range
Dominantly pelitic and quartz-rich schist and quartzite in the Mount Hayes (Nokleberg and others, 1992a), Healy (Csejtey and others, 1992), and Mount McKinley (Bela Csejtey, Jr., written commun., 1993) quadrangles; includes subordinate calc-schist and feldspathic schist. Generally underwent greenschist to amphibolite facies metamorphism, with or without greenschist facies retrogression. Unit is lithologically similar to units PzPxyqs and PzPxyqm in the Yukon-Tanana Upland; all three units contain metaigneous rocks that yield Devonian zircon ages

Source map information

Source map Csejtey, Bela, Jr., Mullen, M.W., Cox, D.P., and Stricker, G.D., 1992, Geology and geochronology of the Healy quadrangle, south-central Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-1961, 63 p., 2 sheets, scale 1:250,000.
Symbol PzpCp
Unit name Pelitic and quartzose schist sequence [old, abandoned Birch Creek Schist]
Description Intercalated in various proportions: medium- to fine-grained, generally medium-gray quartz-sericite and (or) muscovite pelitic schist; fine- to medium-grained, medium-gray quartzite; quartz-sericite and (or) muscovite-calcite pelitic schist; fine-grained dark-gray to black carbonaceous schist or phyllite; a few interbeds, as much as several tens of meters thick of medium-gray, fine-to medium-grained massive marble; and a few small bodies and layers of chloritic schist.
Lithology Metamorphic

Correlated geologic units

Label PzZaqs
Description Pelitic and quartzose schist of the Alaska Range
Geologic age Paleozoic to Devonian
Geologic setting Sedimentary, undivided
Lithology Form Importance
Pelitic-schist < Metaclastic < Metasedimentary < Metamorphic Greenschist Major
Quartzite < Metaclastic < Metasedimentary < Metamorphic Greenschist Major
Phyllite < Metaclastic < Metasedimentary < Metamorphic Greenschist Minor