Katakturuk Dolomite

Unit symbol: Pxkd
Age range Proterozoic (1600 to 541 Ma)
Lithology: Sedimentary
Group name: Katakturuk Dolomite
Defined by Dutro (1970), unit of northeastern Alaska is entirely dolostone except for about 75 m of shaly, dolomitic silty beds near its base. It is locally stromatolitic, sometimes with chert nodules and sparry karst infillings, and may be interbedded with lesser black siltstone and shale, laminated mudstone, and quartzose sandstone; unit also locally contains dolostone boulder conglomerate (Bader and Bird, 1986; Robinson and others, 1989). Dutro (1970) informally divided unit into 9 lithologic units and assigned an age of Middle Devonian or older. Blodgett and others (1986) reassigned age to the Proterozoic on basis of the stratigraphic relation with overlying Nanook Limestone (included in unit DZnl here; of Devonian to Ediacaran age). Clough and Goldhammer (2000) describe the Katakturuk Dolomite as a south-dipping, low-angle, distally steepened carbonate ramp complex that has a complete spectrum of facies types, from proximal, updip tidal-flat complexes to distal, downdip, turbidites and debris-flow deposits. They believe it represents passive-margin cyclic sedimentation and provides insight into the evolution of Precambrian carbonate platforms in response to eustatic sea-level changes. Macdonald (2011) advocates separating a unit at the base of the Katakturuk Dolomite into his informally named Hula Hula diamictite, an orange-weathering conglomerate that has clasts of volcanic rocks (presumably from unit <v described below). He suggests that this proposed subunit was deposited under glacial influence, but this interpretation is not yet universally accepted

Source map information

Source map Reiser, H.N., Brosge, W.P., Dutro, J.T., Jr., and Detterman, R.L., 1971, Preliminary geologic map, Mt. Michelson quadrangle, Alaska: U.S. Geological Survey Open-File Report 71-237, 2 sheets, scale 1:200,000.
Symbol Sk
Unit name Katakturuk Dolomite
Description Dolomite; stromatolitic, pisolitic, cross-bedded; silty shale in lower port.
Lithology Sedimentary

Correlated geologic units

Label Pxkd
Description Katakturuk Dolomite and Lake Gp.: Dolostone and silty dolostone, locally stromatolitic, locally with chert nodules and sparry karst infillings, interbedded with lesser black siltstone and shale, laminated mudstone, and quartzose sandstone; local dolomite boulder conglomerate
Geologic age Mesoproterozoic to Neoproterozoic
Geologic setting Sedimentary, carbonate
Lithology Form Importance
Dolostone < Carbonate < Sedimentary Bed Major
Black-shale < Shale < Mudstone < Clastic < Sedimentary Bed Minor
Siltstone < Clastic < Sedimentary Bed Minor
Sandstone < Clastic < Sedimentary Bed Incidental