REFERENCE MEASURED SECTION FOR THE DESMOINESIAN STRATA OF WESTERN ARKANSAS

Desmoinesian strata of the late Paleozoic Arkoma Basin in western Arkansas all have their stratigraphic type sections defined 100 miles to the west in Oklahoma. To support local U.S. Geological Survey geologic mapping, an 800 m thick composite Desmoinesian stratigraphic section was measured along several gullies on the south side of Mt Magazine and on Short Mountain near Paris, Arkansas. This section establishes local depositional environments, spatial continuity and stacking patterns for the units in this area and supports regional correlations. Recently acquired 1m-resolution LiDAR elevation data was used to map internal units and provide ties between different parts of the section. Map units covered in the section are the Hartshorne Sandstone, McAlester, Savanna, and Boggy formations. Depositional environments include deltaic, fluvial, tidal, and shallow marine settings. Barforms, tidal bundles, and flaser bedding are common in the sandstones and shales that make up the composite section. The basic stacking pattern found in this stratigraphic section matches that of the type descriptions and 1:24:000 scale mapping in Oklahoma. The basal unit of the Boggy Formation, the Bluejacket Sandstone Member, exhibits a distinct detrital zircon signature that is unlike the units below and above. This provides a unique marker of provenance that allows us to confidently map this unit on Short Mountain and Horseshoe Mountain, which narrows down the mapping in this area