Quartzite and pelitic schist

Unit symbol: PzPxyqs
Age range Devonian and older (635 to 358.9 Ma)
Lithology: Metamorphic
Group name: Pelitic schist and quartzite and mafic interbeds (Yukon-Tanana crystalline complex)
Dominantly quartzite, schistose quartzite, and quartz-mica schist; also contains subordinate gritty quartzite, chlorite schist, calc-silicate schist, marble, magnetite-biotite schist, amphibolite, and greenstone. Ranges from amphibolite to upper greenschist facies and locally retrograded to lower greenschist facies (Nokleberg and others, 1992a; Smith and others, 1994). Corresponds, in part, to the Fairbanks schist of Newberry and others (1996) of the Fairbanks mining district and surrounding areas of the southeastern Livengood and northeastern Fairbanks quadrangles (Robinson and others, 1990; Weber and others, 1992; Newberry and others, 1996) as well as a large portion of the Circle quadrangle (Foster and others, 1983). Smaller areas of exposure occur in the southern Big Delta quadrangle (Weber and others, 1978) and in the Eagle quadrangle (Foster, 1976). In the Circle quadrangle and northern Big Delta quadrangle, small exposures of gray or greenish-gray marble and gray to cream-colored dolomitic marble are included in this unit; diopside is present locally, indicating amphibolite facies metamorphism. No age control exists for these carbonate rocks

Source map information

Source map Pewe, T.L., Wahrhaftig, Clyde, and Weber, Florence, 1966, Geologic map of the Fairbanks quadrangle, Alaska: U.S. Geological Survey, Miscellaneous Investigations I-455, 5 pages, 1 sheet, scale 1:250,000.
Symbol bc
Unit name Birch Creek Schist
Description Light- to dark-gray, reddish-brown to tan-weathering schists, predominately quartz-sericite schist and micaceous quartzite. Includes mu-bio schist, garnet-mica schist, calcite-and dolomite-bearing schist, chloritic and graphitic schist, amphibolite, impure marble, and gneiss. Southern most part assigned to NSACLASS = 9322, part out in flats assigned to NSACLASS = 6511
Lithology Metamorphic

Correlated geologic units

Label PzZyqs
Description Quartzitic and pelitic schist of the Yukon-Tanana crystalline complex
Geologic age Paleozoic to Devonian
Geologic setting Sedimentary, shallow-marine-siliciclastic
Lithology Form Importance
Quartzite < Metaclastic < Metasedimentary < Metamorphic Amphibolite, epidote-amphibolite Major
Mica-schist < Schist < Metamorphic Amphibolite, epidote-amphibolite Major
Amphibolite < Metamorphic Amphibolite, epidote-amphibolite Minor
Biotite-gneiss < Gneiss < Metamorphic Amphibolite, epidote-amphibolite Minor