Deep-water lithofacies and conodont faunas of the Lisburne Group, west-central Brooks Range, Alaska

Bulletin 2068
By: , and 



Deep-water lithofacies of the Lisburne Group occur in thrust sheets in the western part of the foreland fold and thrust belt of the Brooks Range and represent at least three discrete units. The Kuna Formation (Brooks Range allochthon) consists mostly of spiculitic mudstone and lesser shale; subordinate carbonate layers are chiefly diagenetic dolomite. Predominantly shale sections of the Kuna that contain few sponge spicules occur in the western part of the study area. The Akmalik Chert (Picnic Creek allochthon) is mostly radiolarian-spiculitic chert; rare limy beds are calcitized radiolarite. The Rim Butte unit (Ipnavik River allochthon) consists chiefly of calcareous turbidites, derived from both shallow- and deep-water sources, interbedded with spiculitic mudstone. Much of the material in the turbidites came from a contemporaneous carbonate platform and margin, but some fossils and lithic clasts were eroded from older, already lithified carbonate-platform rocks. All three units appear to be roughly coeval and are chiefly Osagean (late Early Mississippian) in age in the study area.

Shallow-water lithofacies of the Lisburne Group exposed in the Howard Pass area (Brooks Range allochthon) are mostly of Meramecian (early Late Mississippian) age. Thus, these carbonate-platform rocks were not the source of the calcareous turbidites in the Rim Butte unit. Rim Butte turbidites could have been derived from older platform carbonate rocks such as those of the Utukok Formation (Kelly River allochthon) exposed mainly to the west of the Howard Pass quadrangle.

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Publication type Report
Publication Subtype USGS Numbered Series
Title Deep-water lithofacies and conodont faunas of the Lisburne Group, west-central Brooks Range, Alaska
Series title Bulletin
Series number 2068
DOI 10.3133/70180218
Year Published 1993
Language English
Publisher U.S. Government Printing Office
Publisher location Washington, D.C.
Contributing office(s) Alaska Science Center, Alaska Science Center Geology Minerals
Description 19 p.
Larger Work Type Report
Larger Work Subtype USGS Numbered Series
Larger Work Title Geologic studies in Alaska by the U.S. Geological Survey, 1992 (Bulletin 2068)
First page 12
Last page 30
Country United States
State Alaska
Other Geospatial Brooks Range, Lisburne Group
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