Tolovana Limestone

Unit symbol: DSt
Age range Middle Devonian to Silurian, Llandovery? (443.4 to 382.7 Ma)
Lithology: Sedimentary
Group name: Shallow-marine, carbonate-dominated rocks
“Lower part consists of alternating green and maroon lime mudstone, succeeded by yellowish-brown weathering, silty, shaly lime mudstone and wackestone having brachiopods; its upper and greater part consists of light-gray weathering peloid- and ooid-rich lime packstone and grainstone and rare dolomite” (Weber and others, 1992). As exposed in the White Mountains of the Livengood quadrangle, “appears to be more than 1,200 m thick and of Silurian age based on conodonts and brachiopods, as well as corals.” The depositional environment is interpreted as shallow marine (Weber and others, 1992). In the same strike belt in southeastern Livengood quadrangle, a somewhat younger (Middle Devonian) unit of lime mudstone and wackestone has also been assigned to the Tolovana Limestone; this subunit continues into the Fairbanks and Kantishna River quadrangles (Wilson and others, 1998). Rocks formerly correlated with the Tolovana Limestone in the northwesternmost Circle quadrangle (Foster and others, 1983) were re-assigned to the Schwatka unit of Weber and others (1992) (Wilson and others, 1998), which is here assigned to the Ogilvie Formation (unit Dof); rocks formerly assigned to the Tolovana Limestone in the north-central and northeastern Circle quadrangle (Foster and others, 1983) are here assigned to unit DSld, shallow-marine carbonate-dominated 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 DSt
Unit name Tolovana (?) Limestone
Description Thick-bedded to massive, fine-crystalline to lithographic, medium dark bluish-gray limestone of unknown thickness. Weathers buff to yellowish-brown. Chert rare or absent. Correlated on basis of lithology and geographic trend.
Lithology Sedimentary

Correlated geologic units

Label DSt
Description Tolovana Limestone, Middle Devonian to Early(?) Silurian,
Geologic age Llandovery to Middle-Devonian
Geologic setting Sedimentary, carbonate
Lithology Form Importance
Limestone < Carbonate < Sedimentary Bed Major
Dolostone < Carbonate < Sedimentary Bed Incidental