Staniukovich Formation

Unit symbol: Kst
Age range Lower Cretaceous (145 to 132.9 Ma)
Lithology: Sedimentary
Group name: Staniukovich and Naknek Formations, Kotsina Conglomerate, and similar rocks of southern Alaska
Composed of 246 m of light-olive-gray siltstone and contains two light-olive-brown sandstone intervals, which are overlain by shaly olive-gray siltstone that contains numerous calcareous nodules and concretions (Detterman and others, 1996). Upper part of formation erodes readily and, therefore, is typically not well exposed. Upper part of unit contains few age-diagnostic fossils, whereas lower part has abundant megafauna, particularly the pelecypod Buchia, which indicate Berriasian and Valanginian age (J.W. Miller, written commun., 1982–88; Detterman and others, 1996). Upper and lower contacts of Staniukovich are conformable with Herendeen (Khe) and Naknek (Jn) Formations, respectively. Originally named Staniukovich Shale by Atwood (1911, p. 25, 38) for exposures on Staniukovich Mountain on the southern Alaska Peninsula. Burk (1965) changed name to Staniukovich Formation and mistakenly included within unit a variety of rocks of latest Jurassic and Early Cretaceous age; however, Detterman and others (1996) stratigraphically restrict the formation to original usage of Atwood (1911), and, as so restricted, its age is Early Cretaceous

Source map information

Source map Wilson, F.H., Detterman, R.L., Miller, J.W., and Case, J.E., 1995, Geologic map of the Port Moller, Stepovak Bay, and Simeonof Island quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigation Map I-2272, 2 sheets, scale 1:250,000.
Symbol Kst
Unit name Staniukovich Formation
Description Composed of 246 m of light-olive-gray siltstone containing two light-olive-brown sandstone intervals, overlain by shaly olive-gray siltstone containing numerous calcareous nodules and concretions (Detterman and others, 1996) in type section.
Lithology Sedimentary

Correlated geologic units

Label Kst
Description Staniukovich Formation
Geologic age Berriasian to Valanginian
Geologic setting Sedimentary, shallow-marine-siliciclastic
Lithology Form Importance
Shale < Mudstone < Clastic < Sedimentary Bed Major
Siltstone < Clastic < Sedimentary Bed Major
Sandstone < Clastic < Sedimentary Bed Incidental