Wales Group marble

Unit symbol: CPxwgm
Age range Cambrian to Proterozoic (635 to 485.4 Ma)
Lithology: Metamorphic
Group name: Wales Group, undivided
Medium- to fine-grained, medium- to light-gray marble in thin layers associated with schistose metavolcanic rocks of the Wales Group. Locally, the marble is massive and ranges up to 300 m in thickness (Eberlein and others, 1983). Herreid and others (1978) describe dolomitic marble that forms thick, planar, fine-grained, medium- to light-gray beds that stand out in relief relative to interlayered marble. Near the contact with Wales Group greenschist, tabular dolostone bodies in the marble have been deformed into boudins 10 to 30 m long and up to 10 m thick. Locally, irregular, folded dolostone bodies have marble beds draped around them, suggesting deformation of the rocks after deposition of the dolomite. In a few places, dolomite veinlets crosscut the marble (Herreid and others, 1978)

Source map information

Source map Brew, D.A., compiler, 1996, Geologic map of the Craig, Dixon Entrance, and parts of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-2319, 53 p., 1 sheet, scale 1:250,000.
Symbol CZwm
Unit name Wales Group - Marble and minor calcsilicate rocks
Description Medium to fine grained, medium to light-gray and tan marble. Present as both thin and meter thick layers in greenstone, greenschist, black phyllite, quartz-sericite schist, metakeratophyre, and minor marble, and as massive to very thick (200 m) masses.
Lithology Metamorphic

Correlated geologic units

Label PzZc
Description Wales Group marble
Geologic age Ediacarian to Cambrian
Geologic setting Sedimentary, carbonate
Lithology Form Importance
Marble < Metacarbonate < Metasedimentary < Metamorphic Major