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 Nokleberg, W.J., Aleinikoff, J.N., Lange, I.M., Silva, S.R., Miyaoka, R.T., Schwab, C.E., and Zehner, R.E., with contribution for selected areas from Bond, G.C., Richter, D.H., Smith, T.E., and Stout, J.H., 1992, Preliminary geologic map of the Mount Hayes quadrangle, eastern Alaska Range, Alaska: U.S. Geological Survey Open File Report 92-594, scale 1:250,000 [Received as CAD coverage produced in 1996].
Symbol jcs
Unit name Fine-grained metasedimentary rocks
Description Chiefly fine-grained, mylonitic, metasedimentary rocks. Rocks consist of 65 percent quartz-mica schist, 15 percent quartzite, and 5 percent each of chlorite-white mica schist, quartz-biotite schist, calc-schist, and marble. Metamorphism ranges from lower greenschist to lower amphibolite facies. Intensely deformed exhibiting strong schistosity which dips gently to moderately north or south.
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