Abstract: Upper Cretaceous Sequence Stratigraphy of the Mississippi-Alabama Area

Ernest A. Mancini, T. Markham Puckett, Berry H. Tew, Charles C. Smith

Three depositional sequences associated with cycles of change in relative sea level and coastal onlap can be identified in the Upper Cretaceous (Santonian though Maastrichtian) strata of the Mississippi-Alabama area. These depositional sequences have an event spacing of 1 to 12 million years and are herein designated the UZAGC-3.1 (Upper Zuni A, Gulf Coast), UZAGC-4.1, and UZAGC-5.1 sequences. The UZAGC-3.1 cycle includes a lower type 1 sequence boundary (Tuscaloosa-Eutaw contact); lowstand systems tract (Eutaw Formation); first transgressive surface or disconformity (Eutaw-Tombigbee contact); transgressive systems tract (Tombigbee Sand Member of the Eutaw Formation and the lower Mooreville Chalk); surface of maximum transgression (within the Mooreville); and highstand sy tems tract (upper Mooreville and its Arcola Limestone Member, basal Demopolis sandy beds, Coffee Sand, Tupelo Tongue of the Coffee Sand). The UZAGC-4.1 cycle includes a lower type 2 sequence boundary (Coffee or Tupelo Tongue contact with the Demopolis or Sardis Formation or a contact recognized within the Demopolis), which is coincident with the first transgressive surface; transgressive systems tract (Demopolis marls, Sardis sands); surface of maximum transgression (within the Demopolis Chalk); and highstand systems tract (Demopolis and its Bluffport Marl Member, Coon Creek Formation, Ripley Formation, McNairy Sand). The UZAGC-5.1 cycle includes a lower type 1 sequence boundary (McNairy contact with the Owl Creek Formation or Chiwapa Sandstone Member of the Ripley Formation or a disconf rmity recognized within the Ripley), which can be coincident with the first transgressive surface; transgressive systems tract (Chiwapa or Ripley calcareous sands, Prairie Bluff or Owl Creek marls); surface of maximum transgression (within the Prairie Bluff Chalk or Owl Creek Formation); and highstand systems tract (Prairie Bluff or Owl Creek).

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana