--> The Elm Creek Formation (Wichita-Albany Group) in North Central Texas, by T. R. Walsh; #90903 (2001)

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The Elm Creek Formation (Wichita-Albany Group) in North Central Texas

T. R. Walsh
Geosciences Dept., Texas Tech Univ., Lubbock, TX ([email protected])

The Elm Creek Formation of the Wichita-Albany Group is one of a series of regionally extensive Lower Permian platform carbonates deposited on the western limb of the Bend Arch across the Eastern Shelf of the Permian basin. Deposition occurred during the Artinskian, as determined with sparse conodonts from the Elm Creek. The Elm Creek outcrop is roughly linear, trending north/south, and along with other thick limestones of the Wichita-Albany Group form prominent bluffs through North Central Texas. The formation exhibits regional dip of only one degree or less basinward, to the west, although local variations associated with minor structures have been reported.

Along outcrop the Elm Creek Formation exhibits a general transition from terrestrial facies north of the Brazos to more marine southward, with the thickest carbonate sections recorded near the Colorado River. Normal marine conditions apparently did not exist in this part of the Eastern Shelf during Elm Creek deposition. Carbonates are generally skeletal packstones and wackstones of molluscan (dominantly bivalves) debris with an increasing proportion of calcareous encrusting foraminifera towards the south. Many organisms of typical Permian assemblages are absent or limited. Brachiopods have only been found at two localities throughout the entire Elm Creek outcrop area. Fusulinids have not been detected and conodonts have only recently been recovered from a few beds. The only typical Paleozoic taxa present to any extent, fenestrate and cryptostome bryozoans, are found locally with echinoid debris, primarily in the upper beds of the formation.

AAPG Search and Discovery Article #90903©2001 AAPG Mid-Continent Meeting, Amarillo, Texas