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Brendon D.J. Bailey1, Katherine A. Giles1
(1) New Mexico State University, Las Cruces, NM

Abstract: Applying Ichnology to Sequence Stratigraphy: An Example from the Abo and Hueco formations (Lower Permian), Orogrande Basin, NM

The Abo and Hueco formations, which range from continental siliciclastics to shallow marine carbonates respectively, were deposited in the Orogrande basin during Wolfcampian time. Outcrops in south-central New Mexico provide for ichnologic study along a nonmarine-marine depositional gradient within a mixed carbonate-siliciclastic system. Detailed ichno-sedimentological analyses of these formations demonstrate the paleoenvironmental significance of ichnofossils within a multitude of depositional settings. Ichnologic variations reflect changes in environmental energy, sedimentation rates, and substrate consistency that are consistent with sea-level cycles and current sequence stratigraphic models. This study provides a framework for the creation of predictive stratigraphic models for the Permian based on the integration of ichnofossils and sedimentology.

The Abo Formation in this study consists of continental redbeds representing fluvial, floodplain, and eolian deposition. Ichnofossils are typically abundant, but with low diversity. Meniscate burrows (Scoyenia, Muensteria) and vertebrate tracks dominate, with insect tracks, and grazing trails locally abundant. Basinward, tidal flat and estuarine siliciclastics are interbedded with shallow marine carbonates of the Hueco Formation. Marginal marine siliciclastic lithofacies (lowstand and transgressive systems tracts) are dominated by vertebrate tracks, Monocraterion, Skolithos, Planolites, and arthropod trackways. The moderate diversity and low abundance of ichnofossils may be indicative of fluctuating salinity related to tidal processes. The highstand carbonate lithofacies are dominated by Chondrites, Planolites, Thalassinoides, Diplocraterion, and Rhizocorallium and possess high ichnofossil diversity and abundance. The substrate-controlled Glossifungites ichnofacies overprints the resident highstand ichnoassemblages and characterizes discontinuity surfaces that may relate to transgressive flooding surfaces.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana