Facies comparison of autochthonous and allochthonous Permian and Triassic units, north-central Brooks Range, Alaska
Eight stratigraphic sections of Permian and Triassic rocks have been studied over a 30 km by 150 km area in the Endicott and Philip Smith Mountains of the central Brooks Range. Six of the sections are located on the Endicott Mountains allochthon, and the remaining two are parautochthonous columns in the Mount Doonerak area. The sections record a facies transition between the autochthonous Sadlerochit Group and Shublik Formation of the northeastern Brooks Range and the characteristically siliceous rocks of the allochthonous Siksikpuk and Otuk formations of the western Brooks Range. Laterally continuous and bioturbated beds of fine-grained sandstone, siltstone, and shale dominantly compose the Permian sequence, whereas the Triassic rocks consist of black shales, thin rhythmically bedded siliceous mudstones, and fossiliferous limestones. When the allochthonous sections are restored to a position south of the Mount Doonerak area, a general shallowing trend from southwest to northwest becomes evident within the reconstructed marine basin. To the south and west, the Permian sediments show a marked increase in silica content, with the occurrence of barite and a corresponding decrease in the thickness of the basal, coarser grained clastics. The Triassic formations also document an increase in silica and the presence of barite to the south and west, while becoming significantly sooty and phosphatic to the north and east. Ongoing petrographic and micropaleontologic studies of the field data will clarify these general paleogeographic relationships.
- Research Organization:
- Univ. of Alaska, Anchorage
- OSTI ID:
- 6319203
- Report Number(s):
- CONF-8505215-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 69:4; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Lower Paleozoic and Proterozoic rocks of Southern Brooks Range, Alaska
Age and correlation of the Otuk formation, North-Central Brooks Range, Alaska
Related Subjects
020200* -- Petroleum-- Reserves
Geology
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ALASKA
BITUMINOUS MATERIALS
BLACK SHALES
CARBONACEOUS MATERIALS
CARBONATE ROCKS
CHATTANOOGA FORMATION
ENERGY SOURCES
FEDERAL REGION X
FOSSIL FUELS
FUELS
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGY
LIMESTONE
MATERIALS
MESOZOIC ERA
NORTH AMERICA
OIL SHALES
PALEOZOIC ERA
PERMIAN PERIOD
PETROLEUM GEOLOGY
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SILTSTONES
STRATIGRAPHY
TRIASSIC PERIOD
USA