Effects of climate, tectonics, and sea-level changes on rhythmic bedding patterns in the Niobrara Formation (Upper Cretaceous), US Western Interior

Journal Article · Sun Mar 01 00:00:00 EST 1987 · Geology; (United States)

OSTI ID:5340416

Laferriere, A P; Hattin, D E; Archer, A W

Regional correlation of interbedded pelagic/hemipelagic limestones and calcareous shales of the Fort Hays Limestone Member of the Niobrara Formation confirms development of at least two levels of cyclicity. Occurrence of time-parallel rhythmically deposited beds that can be correlated over distances exceeding 800 km lends strong support to the hypothesis that these cycles were induced by Milankovitch-type climatic forcing. However, visual observation and Fourier analysis of variations in shale and limestone thickness demonstrate that the pattern of Fort Hays cyclicity lacks regional uniformity. Complications in the cyclic pattern may have resulted from the influence of orbital parameters having differing periodicities. Additionally, departures from simple cyclical patterns resulted from sedimentary effects of the Sevier orogeny and from erosional events associated with sea-level changes. Documentation of thickness variations within the regionally persistent Fort Hays bedding sequence furnishes a basis for fine-scale analysis of Cretaceous crustal movements within the Western Interior seaway.

• Research Organization: Indiana Univ., Bloomington (USA)
• OSTI ID: 5340416
• Journal Information: Geology; (United States), Vol. 15:3
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
COLORADO
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
STRATIGRAPHY
DEPOSITION
LIMESTONE
PALEOCLIMATOLOGY
SEA LEVEL
SHALES
TECTONICS
THICKNESS
VARIATIONS
CARBONATE ROCKS
DIMENSIONS
FEDERAL REGION VIII
GEOLOGY
LEVELS
NORTH AMERICA
PALEONTOLOGY
ROCKS
SEDIMENTARY ROCKS
USA
580100* - Geology & Hydrology- (-1989)