Conodont biostratigraphy and biofacies of the Wahoo Limestone (Carboniferous), Sadlerochit Mountains, northeast Brooks Range, Alaska
- Univ. of Alaska, Fairbanks (USA)
- Geological Survey, Reston, VA (USA)
The Wahoo Limestone forms the upper part of the Lisburne Group (Carboniferous) in the Sadlerochit Mountains. The Lisburne Group is a thick (> 600 m) sequence of platform carbonate rocks that extends across the Brooks Range of northern Alaska and beneath the North Slope. At Prudhoe Bay, the Lisburne Group forms a major hydrocarbon reservoir. In the easternmost Sadlerochit Mountains, the Wahool Limestone is divisible into informal lower (64 m) and upper (192 m) members. The basal 46 m is chiefly bryozoan and pelmatozoan packstone that formed on a relatively shallow platform during the latest Mississippian lower muricatus subzone (as shown by the occurrence of the zonal index with representatives of Cavusgnathus). Cavusgnathus is dominant in this part of the section and occurs with representatives of Kladognathus, Ghathodus, Adetognathus, Hindeodus, and Rhachistognathus (in order of decreasing abundance). Declinognathodus noduliferus, the index for the base of the Pennsylvanian, first occurs at 49 m above the base of the Wahoo and 1 m above a discontinuity surface that marks the Mississippian-Pennsylvanian boundary. The unconformity represents the highest conodont subzone of the Mississippian and probably part of the earliest Pennsylvanian. Previously, the Mississippian-Pennsylvanian boundary was placed t the lower-upper Wahoo contact based on endothyroids; conodont data now indicate that this boundary is 15 m lower. The remaining lower Wahoo is possibly of noduliferus-primus zone age and chiefly yields, in order of decreasing abundance, species of Adetognathus, Declinognathodus, and Rhachistognathus, as well as redeposited Mississipian conodonts. The lower 15 m of the upper member of the Wahoo contains silty (5-40%) carbonate rock types that yield very few conodonts. Conodonts no older than the minutus-sinuatus zone are relatively abundant from 15 to 106 m above the base of the upper Wahoo.
- OSTI ID:
- 6693844
- Report Number(s):
- CONF-900605-; CODEN: AABUD
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Conodont biostratigraphy and biofacies of the Lisburne Group
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Related Subjects
ALASKA
LIMESTONE
STRATIGRAPHY
ALASKAN NORTH SLOPE
CARBONIFEROUS PERIOD
FOSSILS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
PRUDHOE BAY
ARCTIC OCEAN
BAYS
BEAUFORT SEA
CARBONATE ROCKS
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGY
NORTH AMERICA
PALEOZOIC ERA
ROCKS
SEAS
SEDIMENTARY ROCKS
SURFACE WATERS
USA
580000* - Geosciences