Metasedimentary rocks of Bluecloud Mountain

Unit symbol: PzPxb
Age range early Paleozoic to Proterozoic? (1000 to 485.4 Ma)
Lithology: Metamorphic
Group name: Metasedimentary and metavolcanic rocks of the Central Belt and Northern Thrust assemblage of Till and others (2008a)
Light- to dark-gray phyllite, dark-gray to black metaquartzite, dark-gray and grayish-brown calcareous phyllite, and reddish-brown-weathering impure marble exposed in fault-bounded lenses along the Schist belt-Central belt contact in the Wiseman quadrangle, as described by Till and others (2008a). Lithologic layering is visible in outcrop where it crosses foliation; locally, lithologic layering is transposed by foliation, which is defined by fine-grained mica. In thin section, lithologic layering and relict clasts are recognizable; metamorphic minerals include white mica, chlorite, stilpnomelane(?), and very fine-grained garnet or albite. No protolith age control is available; the protolith may have been a sequence of turbidites (Till and others, 2008a)

Source map information

Source map Till, A.B., Dumoulin, J.A., Harris, A.G., Moore, T.E., Bleick, Heather, and Siwiec, Benjamin, 2008, Bedrock geologic map of the southern Brooks Range, Alaska, and accompanying conodont data: U.S. Geological Survey Open-File Report 2008-1149, 88 p., 2 sheets, scale 1:500,000.
Symbol PzZb
Unit name Metasedimentary rocks of Bluecloud Mountain
Description Light, medium, and dark gray phyllite, dark gray to black metaquartzite, dark gray and grayish-brown calcareous phyllite, and reddish-brown weathering impure marble exposed in fault-bounded lenses along the Schist belt-Central belt contact in the Wiseman quadrangle. This unit is part of the Central belt.
Lithology Metamorphic

Correlated geologic units

Label PzZb
Description Metasedimentary rocks of Bluecloud Mountain, gray phyllite, dark-gray to black metaquartzite, calcareous phyllite, and impure marble
Geologic age Neoproterozoic to Devonian
Geologic setting Sedimentary, undivided
Lithology Form Importance
Phyllite < Metaclastic < Metasedimentary < Metamorphic Major
Quartzite < Metaclastic < Metasedimentary < Metamorphic Major
Marble < Metacarbonate < Metasedimentary < Metamorphic Minor