Lithostratigraphy of the Shore Airport Formation (Chesterian), Southwestern Kansas

Abstract

The Shore Airport Formation in the Hugoton embayment of the Anadarko basin is a new subsurface stratigraphic unit for peloid packstone and maroon calcareous shale of the previously unnamed strata in the Chesterian Stage. Shore Airport strata in southwestern Kansas are unconformably underlain by the Ste. Genevieve Limestone (Chesterian) and unconformably overlain by the Kearny Formation (Morrowan). Argillaceous Shore Airport strata are distinct from Ste. Genevieve quartzose carbonates that typically contain little shale. Lower Kearny strata generally contain increased percentages of siliciclastic and sandy marine carbonates. The unit is named for the Shore Airport SW 7.5-min quadrangle, Morton County, Kansas. A core from the Amoco #1 Breeding F (sec. 34, T. 31 S., R. 40 W.) contains 40.6 ft (12.4 m) of Shore Airport strata and is designated as the type section.

Two facies are recognized from the type section. Peloid packstone is greenish-gray to maroon in color and is the dominant facies. Paucity of stenohaline marine allochems, fine grain size, and micrite matrix indicate deposition in a low-energy, restricted-shelf environment. Rhizoliths, drab-haloed root traces, and glaebules suggest reddish color in maroon peloid packstone intervals accumulated in a B_s soil horizon (zone of illuvial accumulation of sesquioxides). These paleosols are interpreted as inceptisols (sesquioxide-rich, clay-poor paleosols).

Peloid packstone is intercalated with maroon calcareous shale. Slickensides, glaebules, drab-haloed root traces, rhizocretions, and blocky peds indicate these maroon shale intervals formed in a B_t soil horizon (zone of illuvial accumulation of clay and sesquioxides). The paleosols are interpreted as alfisols (sesquioxide-rich, clay-rich paleosols).