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Cretaceous biostratigraphy in the Wyoming thrust belt.

Mountain Geologist

By:
and

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Abstract

In the Cretaceous section of the thrust belt, fossils are especially useful for dating and correlating repetitive facies of different ages in structurally complex terrain. The biostratigraphic zonation for the region is based on megafossils (chiefly ammonites) , which permit accurate dating and correlation of outcrop sections, and which have been calibrated with the radiometric time scale for the Western Interior. Molluscan and vertebrate zone fossils are difficult to obtain from the subsurface, however, and ammonites are restricted to rocks of marine origin. Palynomorphs (plant microfossils) have proven to be the most valuable fossils in the subsurface because they can be recovered from drill cuttings. Palynomorphs also are found in both marine and nonmarine rocks and can be used for correlation between facies. Stratigraphic ranges of selected Cretaceous marine and nonmarine palynomorphs in previously designated reference sections in Fossil Basin, Wyoming are correlated with the occurrence of ammonites and other zone fossils in the same sections. These correlations can be related to known isotopic ages, and they contribute to the calibration of palynomorph ranges in the Cretaceous of the Western Interior. -from Authors

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Cretaceous biostratigraphy in the Wyoming thrust belt.
Series title:
Mountain Geologist
Volume
19
Issue:
3
Year Published:
1982
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Mountain Geologist
First page:
73
Last page:
78
Number of Pages:
6