Stratigraphy and Sedimentology of the Tombigbee Sand Member, Eutaw Formation (Cretaceous-campanian stage), of Northeastern Mississippi

The Tombigbee Sand Member of the Eutaw Formation in northeastern Mississippi, can be divided into four lithofacies and six biofacies that define an inner nerit:k to middle neritic marine transgressive sequence. The lithofacies range from medium~~ to fine-grained sands deposited above wave base, to silts and clays deposited in lower energy environments. The biofacies a.re defined by assemblages of benthic micro-faunal morphotypes,, The morphotypes exhibit a substrate preference and are associated with certain lithofacies. The lithofacies and biofacies are locally correlatable~ However, the updip variability of the :i.nner neritic environment prohibits regional correlative use of the lithofacies and biofacies. The potential use of the lithofacies and biofacies as a correlative tool for the Tombigbee increases downdip as the more stable middle neritic marine environments are encountered.