Pelitic schist, including Chena River sequence

Unit symbol: PzPxyqm
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)
Medium- to high-grade pelitic schist that contains subordinate quartzite, quartz schist, calc-silicate rocks and calc-schist, marble, amphibolite, graphitic schist, and augen gneiss interlayers. Compared to unit PzPxyqs, this unit contains less quartzite and quartz schist, more marble interlayers, and is of generally higher grade; however, it may have strong similarities in lithology, polymetamorphic history, and metamorphic grade with unit PzPxyqs. The contact with PzPxyqs was interpreted as a thrust fault by Foster and others (1983) in the Circle quadrangle and was also locally mapped as such by Smith and others (1994). In the Eagle quadrangle, unit is closely associated with metaplutonic rocks of unit MDag, possibly as roof pendants to the original plutons

Source map information

Source map Weber, F.R., Foster, H.L., Keith, T.E.C., and Dusel-Bacon, Cynthia, 1978, Preliminary geologic map of the Big Delta quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-529A, scale 1:250,000.
Symbol Pzs
Unit name Schist
Description Quartz-mica schist with marble and quartzite, calcareous diopside schist, quartz-feldspar rock; and amphibolite. Sillimanite is locally abundant near the Salcha River and staurolite, andalusite and kyanite also occur.
Lithology Metamorphic

Correlated geologic units

Label PzZysa
Description Pelitic schist, early Paleozoic or preCambrian, includes Chena River sequence
Geologic age Paleozoic to Devonian
Geologic setting Sedimentary, shallow-marine-siliciclastic
Lithology Form Importance
Schist < Metamorphic Major
Quartzite < Metaclastic < Metasedimentary < Metamorphic Minor