Abstract

The Upper Pennsylvanian Honaker Trail Formation is Missourian – Virgilian in age. It is the uppermost formation of the Hermosa Group. It is composed of cherty, silty carbonates, and calcareous shales, siltstones, and sandstones with no interbedded evaporites. At the end of Pennsylvanian time, the Hermosa Sea withdrew from the Paradox Basin, resulting in an unconformity between the Late Carboniferous and overlying Permian strata. (Grammer and others, 1996).

Four outcrop sections of the Upper Ismay Member of the Paradox Formation and the Honaker Trail Formation were measured along the San Juan River Canyon in southeastern Utah. Twenty-one sandstone, shale and carbonate lithofacies were identified and combined into seven sedimentary facies. A thorough description of the sedimentary facies was adopted from Mark Williams (2009). The 7 sedimentary facies were assigned to broad depositional tracts that are: 1) continental, 2) transitional, and 3) marine.

The Upper Ismay Member of the Paradox and the Lower Honaker Trail Formations (Desmoinesian through early Missourian) are dominated by transitional – marginal marine and open marine carbonates with intermittent tidal flat sandstones and siltstones. The Upper Ismay Member is dominated by marine sediments and it becomes shallower from west to east. The Lower Honaker Trail Formation is characterized by deeper marine deposits on the west and shallow marine to transitional environments on the east. As the cycles transitioned into the Middle Missourian – Virgilian, siliciclastic content increased. The Upper Honaker Trail Formation and the Lower Permian all appear to be predominantly non-marine sands. They consist of very fine to finegrained quartz arenites, lithic arenites, and calcareous subarkoses to arkoses. Generally, these transitional to continental sand deposits are dark-brown to red in color from the hematite that occurs mainly as cement or a grain coating indicating subaerial exposure. These upper cycles were deposited in flood plain, fluvial, and eolian settings.

In the Paradox Basin cycles are represented as deposits formed by sea level rise and fall and exhibit a deepening to shallowing succession of facies. The Paradox cycles represent a mixed system of carbonates and sandstones that were deposited on the shelf of the Paradox Basin (Grammer and others, 1996).

The Pennsylvanian strata on the Eastern Shelf of the Permian Basin are very similar to those located on the shelf of the Paradox Basin. The results from this study can be directly applied to the deposits on the Eastern Shelf and in North Central Texas.