--> A New Atlantic and Gulf Coastal Plain Campanian–Maastrichtian Ammonite Zonal Scheme and Its Correlation with the Classic Western Interior Biozonation
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AAPG Rocky Mountain Section Meeting

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A New Atlantic and Gulf Coastal Plain Campanian–Maastrichtian Ammonite Zonal Scheme and Its Previous HitCorrelationNext Hit with the Classic Western Interior Biozonation

Joshua S. Slattery1, Keith P. Minor2, Peter J. Harries3, Ralph O. Johnson4, and Ashley L. Sandness4


1School of Geosciences, University of South Florida, 4202 East Fowler Ave., NES 107, Tampa, Florida 33620;
2Department of Geology, The University of Texas at Austin, 2275 Speedway Stop C9000; Austin, TX 78712-1722;
3Department of Marine, Earth, and Atmospheric Sciences, Campus Box 8208, North Carolina State University, Raleigh, North Carolina 276958208;
4Tampa Florida, 33613


September 15-18, 2019 – AAPG Rocky Mountain Section Meeting, Cheyenne, Wyoming

Posted: January 16, 2020

Abstract

This project is aimed at re-evaluating and refining the ammonite-based Campanian–Maastrichtian zonal scheme for the Atlantic and Gulf Coastal plains (ACP and GCP, respectively) with the over-arching goal of correlating these zones to those erected for the U.S. Western Interior (WI) by William A. Cobban in conjunction with his collaborators. Both the ACP and GCP share numerous ammonite taxa with the WI; the latter having one of most refined molluscan-based Previous HitbiostratigraphicNext Hit frameworks globally, which has been temporally calibrated by dating of numerous ash beds. The shared species between these regions allow for high-resolution correlations, which are used in this compilation to constrain (or bracket) the Previous HitageNext Hit and duration of GCP and ACP ammonite zones. The ACP and GCP ammonite zones range from 0.3 to 3.3 Ma and have a mean duration of 1.2 ± 1.0 Ma. The durations of these ammonite zones are considerably longer and more variable than the 0.5 ± 0.2 Ma durations for the WI, which likely relates in the ACP and GCP to reduced evolutionary rates for the chosen index taxa, limited exposure of fossiliferous strata, the occurrence of numerous condensed beds, and a paucity of highresolution ammonite-based Previous HitbiostratigraphicNext Hit studies below the upper Maastrichtian. Our ammonite-based zonations for the ACP and GCP are virtually identical and are represented by 14 zones, respectively. Four Campanian ammonites zones extend from the WI into the ACP and GCP based on the shared occurrence of index species. Many of these ammonite zones are applied to these areas for the first time and provide a more comprehensive framework that fills many of the Previous HitbiostratigraphicNext Hit gaps for intervals that have previously been unzoned due to a poor understanding of ammonite range data. These ammonite zones in conjunction with their associated ammonite faunas provide an important link for broad-scale Previous HitcorrelationTop between North America and other parts of the globe.

AAPG Datapages/Search and Discovery Article #90357 ©2019 AAPG Rocky Mountain Section Meeting, Cheyenne, Wyoming, September 15-18, 2019