Cenomanian-Turonian flooding cycles: U.S. Gulf Coast and Western Interior

Abstract

Cenomanian-Turonian ages, 100.5 Ma to 89.8 Ma, represented an extraordinary Cretaceous time interval when continental seaways expanded, tropical waters interchanged with Polar waters, global climates warmed, and at the end of the Cenomanian large amounts of organic carbon were buried. This was a time of major evolutionary changes in marine pelagic and benthic ecosystems, and in terrestrial plant ecosystems. A new comprehensive chronostratigraphic Cretaceous database is built upon reference sections of each Cretaceous stage and is calibrated to the 2016 Geologic Time Scale. This database is composed of bioevents, chemostratigraphic events, radioisotope measurements, and magnetochrons integrated with nearly 3000 species by projecting the section measurements of the events to the numeric time scale.This new database calibrates numerical ages of Cenomanian-Turonian sequence boundaries in Tunisian reference sections. These deep-shelf successions of limestone/marl/shale record biostratigraphically well dated, continuous deposition and serve as a model of Cenomanian-Turonian cycles. The Cretaceous database enables stratigraphic correlation experiments to test the time equivalency of Tunisian depositional cycles with sequences in Europe, in the Eagle Ford Group in Texas and with stratigraphic sequences in the Western Interior. New accurate and precise correlation of Cenomanian-Turonian depositional sequences between the Gulf Coast and the Western Interior test new biostratigraphic and radioisotopic data of the Eagle Ford Group on the Texas Comanche shelf. The Albian-Cenomanian boundary as defined by planktic foraminifers and ammonites in Texas projects between upper Albian shale units and the Dakota Group and associated sandstone units. The Mowry Shale and its endemic ammonites correlate with upper lower Cenomanian zones.