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Sedimentology and Sequence Stratigraphy of the Lower Cretaceous Fortress Mountain and Torok Formations Exposed Along the Siksikpuk River, North-Central Alaska

Professional Paper 1739-D

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Abstract

An exposure of the Lower Cretaceous Fortress Mountain and Torok Formations along the Siksikpuk River in north-central Alaska provides a rare opportunity to observe the stratigraphic contact between these two formations and to interpret the depositional facies and sequence stratigraphy of the exposed strata. The Fortress Mountain Formation at the base of the measured section includes braided-fluvial and coastal-plain facies deposited in a lowstand-systems tract, and an overlying succession of mostly shallow marine facies deposited in the basal part of a transgressive-systems tract. The overlying Torok Formation includes a thick, upward-deepening succession of marine-shelf to marine-slope facies deposited in the upper part of the transgressive-systems tract. The upper part of the section includes marine-slope and incised-slope-channel turbidite deposits of the Torok Formation, interpreted as a highstand-systems tract. Consideration of the balance between accommodation and sediment flux inferred from the sequence-stratigraphic analysis suggests that both tectonics and eustasy may have influenced deposition of the lowstand-systems and transgressive-systems tracts. In contrast, the highstand-systems tract may have been primarily influenced by progradation of a regional sediment-dispersal system and by subsidence induced by sediment loading.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Sedimentology and Sequence Stratigraphy of the Lower Cretaceous Fortress Mountain and Torok Formations Exposed Along the Siksikpuk River, North-Central Alaska
Series title:
Professional Paper
Series number:
1739
Chapter:
D
Edition:
Version 1.0
Year Published:
2007
Language:
ENGLISH
Publisher:
Geological Survey (U.S.)
Contributing office(s):
Western Energy Resources
Description:
Report: 20 p.; Plate: 40 x 36 inches
Larger Work Type:
Report
Larger Work Subtype:
USGS Numbered Series
Larger Work Title:
Studies by the U.S. Geological Survey in Alaska, 2006
Online Only (Y/N):
Y
Additional Online Files(Y/N):
Y