Limestone and marble

Unit symbol: Pzls
Age range Paleozoic (541 to 252.2 Ma)
Lithology: Sedimentary
Group name: Limestone and marble
Unit consists of poorly known limestone and associated rocks generally found as lenses accompanying rocks of unit |<rqm in central Alaska, in isolated exposures ranging from the southern Brooks Range to the Kaiyuh Mountains south of the Yukon River. Best described part of unit is “gray to white, partly to wholly recrystallized limestone, marble, dark-gray dolomitic marble, and impure schistose limestone. Unit occurs in layers as much as 25 m thick intercalated with quartz-mica schist, mica schist, graphitic schist, metabasite, and quartzite. Some contacts are gradational; others are sharp and may be faulted. Unit contains conodonts of Middle Ordovician age in the Nulato quadrangle and poorly preserved corals of Ordovician to Late Mississippian age in Ruby quadrangle” (Patton and others, 2009). In the Tanana quadrangle, unit is light- to medium-gray or tan platy limestone and massive-bedded silicified limestone and dolostone and has extensive locally developed boxwork silica contains sparse conodonts of Famennian age (J.N. Dover, written commun., 1997). In the southeast Circle quadrangle of central Alaska, small bodies of coarse-grained marble are present in the Paleozoic or Precambrian pelitic schist of the region (unit PzPxyqm)

Source map information

Source map Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, 2009, Geologic map of the Yukon-Koyukuk basin, Alaska: U.S. Geological Survey Scientific Investigations Map SIM-2909, 26 p., 2 sheets, scale 1:500,000.
Symbol Pzcr
Unit name Carbonate rocks
Description Gray to white, partly to wholly recrystallized limestone, marble, dark-gray dolomitic marble, and impure schistose limestone. Unit occurs in layers as much as 25m thick intercalated with quartz-mica schist, mica schist, graphitic schist, metabasite, and quartzite. Some contacts are gradational; others are sharp and may be faulted. Scattered small bodies within schistose rocks of unit PzPxsr in Nulato, Ruby, Melozitna, Tanana, and Bettles quadrangles. Map shows only the larger of these bodies that were observed in the field or on aerial photographs. Undoubtedly many additional unrecognized bodies exist in areas mapped as unit PzPxsr. Also included in this unit is a small area of metacarbonate rocks exposed in a window(?) within the thrust-faulted Innoko terrane in east-central Ophir quadrangle
Lithology Metamorphic

Correlated geologic units

Label Pzrm
Description Carbonates, early Paleozoic
Geologic age Paleozoic
Geologic setting Sedimentary, carbonate
Lithology Form Importance
Marble < Metacarbonate < Metasedimentary < Metamorphic Major
Limestone < Carbonate < Sedimentary Calcareous Major
Dolostone < Carbonate < Sedimentary Calcareous Minor