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Deep-water facies of the Lisburne Group, west-central Brooks Range, Alaska

December 31, 1992

Deep-water lithofacies of the Lisburne Group (chiefly Carboniferous) occur in thurst 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. 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 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 in the Howard Pass area and are chiefly late Tournaisian and early Viséan (late Early Mississippian) in age.

Shallow-water lithofacies of the Lisburne Group exposed in the Howard Pass area (Brooks Range allochthon) are mostly of Viséan and younger (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 carbonate-platform rocks such as the Utukok Formation of Tournaisian age (Kelly River allochthon) exposed mainly to the west of the Howard Pass quadrangle.

Publication Year 1992
Title Deep-water facies of the Lisburne Group, west-central Brooks Range, Alaska
Authors Julie A. Dumoulin, Anita G. Harris, Jeanine M. Schmidt
Publication Type Conference Paper
Publication Subtype Conference Paper
Index ID 70187780
Record Source USGS Publications Warehouse
USGS Organization Alaska Science Center