Tag Archive for: Mississippian

Wellsville Mountains, Cache County, Utah
Photographer: Stefan Kirby

Cephalopod fossil in the Mississippian-age Great Blue Limestone along the crest of the Wellsville Mountains, Cache County.

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David E. Eby, Thomas C. Chidsey, Jr., Douglas A. Sprinkel, & Michael D. Laine

Presented at the American Association of Petroleum Geologists annual convention, Denver, CO, June 2009.


Breccia associated with sediment-filled cavities is relatively common throughout the upper third of the Mississippian Leadville Limestone in Lisbon and other fields, Paradox Basin, southeastern Utah. These cavities or cracks are related to karstification of the Leadville during exposure in Late Mississippian time. Infilling of the cavities by detrital carbonate and siliciclastic sediments occurred before deposition of the Pennsylvanian Molas Formation. The transported material consists of poorly sorted detrital quartz grains, chert fragments, and clasts of carbonate and clay. The carbonate muds infilling the karst cavities are very finely crystalline and non-porous dolomites.