The non-transferability of a Cretaceous coal model in the San Juan Basin of New Mexico and Colorado

GSA Special Papers



The San Juan Basin of northwest New Mexico and southwest Colorado contains several Upper Cretaceous coal-bearing formations. The coals in these formations were deposited in environments associated with repeated transgressions and regressions of the Western Interior seaway in Late Cretaceous time. A detailed subsurface and surface study of the coal beds in one of these units, the Fruitland Formation, formed the basis for a coal-depositional model (Fassett and Hinds, 1971). This model basically shows that the thickest Fruitland coals formed landward of thickly stacked sandstone beds of the regressive-marine Pictured Cliffs Sandstone. Transferability of the Fruitland coal model was tested by comparing it to another San Juan Basin coal-bearing rock unit, the lower Menefee Formation. Lower Menefee coal deposits were formed in association with the Point Lookout Sandstone, an older regressive-marine unit. The purpose of this comparison was to see if thick lower Menefee coal beds were also concentrated adjacent to thick vertical shoreface-sandstone buildups. This comparison showed that even though thick sandstone buildups were found in the Point Lookout, no thick coal beds were found in the lower Menefee Formation adjacent to them. This test suggests that certain coal depositional models may have limited value as predictive tools and must be used with caution by coal explorationists. Even more importantly, potential coal-bearing areas should never be written off simply because they do not fit a previously described model.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title The non-transferability of a Cretaceous coal model in the San Juan Basin of New Mexico and Colorado
Series title GSA Special Papers
DOI 10.1130/SPE210-p155
Volume 210
Year Published 1986
Language English
Publisher GSA
Contributing office(s) Central Energy Resources Science Center
Description 18 p.
First page 155
Last page 171
Country United States
State Colorado, New Mexico
Other Geospatial San Juan Basin
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