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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 61 (1977)

Issue: 3. (March)

First Page: 435

Last Page: 442

Title: Mississippian Unconformities in Northern Alaska Related to Antler Tectonic Pulses: GEOLOGIC NOTES

Author(s): F. A. Schoennagel (2)


The Lisburne Group of northern Alaska, a sequence of Carboniferous carbonate rocks, contains several subtle subregional unconformities and abrupt vertical depositional discontinuities. Two of these are present in about the same stratigraphic position as regional Mississippian unconformities in the western United States.

An unconformity within the Wachsmuth Limestone of the Lisburne Group is present in central Brooks Range outcrops in lower or basal Meramecian carbonate and shale. It can be traced as a sharp contact for 70 mi (112 km) along the Brooks Range front. Correlations between outcrops suggest erosional thinning of 105 ft (32 m) in 11 mi (18 km) over part of its area of outcrop.

Another subregional unconformity is within subsurface Chesteran carbonate rocks of the Arctic Slope. Low-angle truncation occurs at the top of a dolomite zone in most of the deep Arctic Slope wells.

In the Cordilleran region of the western United States there was orogenic and epeirogenic unrest during early

End_Page 435------------------------------

Meramecian and again during Chesteran times. Tectonic pulses of the Antler orogeny are reflected in the stratigraphic record outside of, as well as within, the orogenic belt.

Evidence for Antler epeirogenic unrest previously had been reported as far north as Idaho and Montana with a questionable extension into western Canada. The Mississippian unconformities in northern Alaska may be evidence of mild epeirogenic unrest related to the Antler orogeny as far north as the Brooks Range and Arctic Slope, Alaska.

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