Biosiliceous, organic-rich, and phosphatic facies of Triassic strata of northwest Alaska: Transect across a high-latitude, low-angle continental margin
Links
- More information: Publisher Index Page (via DOI)
- Data Release: USGS data release - Geochemical, Geochronologic, Rock-Eval, and Spectral Gamma Ray Data for Selected Triassic Rocks in Northwestern Alaska
- Open Access Version: External Repository
- Download citation as: RIS | Dublin Core
Abstract
The Shublik Formation (Middle and Upper Triassic) is a mixed siliciclastic-carbonate-phosphatic unit in northern Alaska. It generated oil found in Prudhoe Bay and other accumulations and is a prospective self-sourced resource play on Alaska’s North Slope. Its distal, deeper-water equivalent—the Otuk Formation—consists largely of radiolarian chert, mudstone, and limestone and contains potential gas accumulations in the Brooks Range foothills to the south. New petrographic, fossil, geochemical, spectral gamma-ray, and zircon U-Pb data yield insights into facies changes in these units, which were deposited across a shallowly dipping shelf margin in a high-latitude setting. Samples come from four localities along a transect that extends ~410 km from present-day northeast (proximal) to southwest (distal) in northwest Alaska. Proximal Shublik facies (Brontosaurus 1 well) contain abundant siliciclastic detritus and local phosphate. Shublik-Otuk transitional facies occur in the probable onshore extension of the Hanna Trough (Surprise Creek); new zircon U-Pb data indicate an early Norian age for a bentonite bed in this section. Distal Otuk facies (Red Dog district, Cape Lisburne) are fine grained, biosiliceous, and organic rich. New detrital zircon U-Pb data from a distinctive sandstone member in the Otuk Formation at Cape Lisburne reinforce previous interpretations of a provenance to the present-day northwest and indicate a protracted history of Triassic magmatism for this source area. Triassic facies patterns in northwestern Alaska were shaped by sea-level change, climate, and regional tectonism. Organic-rich facies developed best at times (Ladinian–middle Norian) and/or in settings (distal shelf, Hanna Trough) with minimal dilution of organic matter by other detritus.
Suggested Citation
Dumoulin, J.A., Whidden, K.J., Rouse, W.A., Lease, R.O., Boehlke, A., O’Sullivan, P., 2022, Biosiliceous, organic-rich, and phosphatic facies of Triassic strata of northwest Alaska: Transect across a high-latitude, low-angle continental margin, chap. of Understanding the Monterey Formation and similar biosiliceous units across space and time, v. 556, p. 243-271, https://doi.org/10.1130/2022.2556(11).
Study Area
| Publication type | Book chapter |
|---|---|
| Publication Subtype | Book Chapter |
| Title | Biosiliceous, organic-rich, and phosphatic facies of Triassic strata of northwest Alaska: Transect across a high-latitude, low-angle continental margin |
| DOI | 10.1130/2022.2556(11) |
| Volume | 556 |
| Year Published | 2022 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Alaska Science Center Geology Minerals, Central Energy Resources Science Center |
| Description | 29 p. |
| Larger Work Type | Book |
| Larger Work Subtype | Monograph |
| Larger Work Title | Understanding the Monterey Formation and similar biosiliceous units across space and time |
| First page | 243 |
| Last page | 271 |
| Country | United States |
| State | Alaska |