Upper Jurassic Ammonites from the Subsurface of Texas, Louisiana, and Mississippi
Ralph W. Imlay, George Herman, 1984. "Upper Jurassic Ammonites from the Subsurface of Texas, Louisiana, and Mississippi", The Jurassic of the Gulf Rim, William P. S. Ventress, Don G. Bebout, Bob F. Perkins, Clyde H. Moore
Download citation file:
Ammonites ranging in age from late middle Oxfordian to latest Tithonian have been found in cores obtained from nine wells in Louisiana, one well in Mississippi, six wells in eastern Texas, and one well in southern Texas. The ammonites found in the middle and upper parts of the Smackover Formation are of late middle to late Oxfordian age based on the presence of Ochetoceras, Proscaphites, Dichotomosphinctes, Discosphinctes, Ortho-sphinctes, Idoceras, and Euaspidoceras. The lower part is probably also entirely of that age based on the presence of Discosphinctes at the top of the lower fifth of the Smackover Formation in the Carter-Hope Fee No. 1 well. No ammonites have been found in the red beds typical of the Buckner Formation, but the overlying Gilmer Limestone has furnished a few specimens of Idoceras of late Oxfordian, or early Kimmeridgian age. The basal beds of the younger Bossier Formation have yielded the early Kimmeridgian ammonites Nebrodites and Ataxioceras in association with Idoceras. Above these strata are beds characterized by the Kimmeridgian genus Procraspedites and also by Glochiceras and Taramelliceras, which range as high as the basal Tithonian. The upper and middle parts of the Bossier Formation are characterized by a few ammonite genera of Tithonian age including Virgatosphinctes, Salinites, Durangites?, and Substeueroceras.