Matthew P. Garb
Neil H. Landman
Natalie Dastas
Nicolas Thibault
Lucy E. Edwards
George Phillips
Remy Rovelli
Corinne Myers
Jone Naujokaityte
Ekaterina Larina
2016
<p><span>The Cretaceous outcrop belt of the Mississippi Embayment in the Gulf Coastal Plain (GCP) spans the Cretaceous/Paleogene (K/Pg) boundary. A detailed reconstruction of this time interval is critical for understanding the nature of biotic and environmental changes preceding the end-Cretaceous Mass Extinction event and for deciphering the likely extinction mechanism (i.e., bolide impact versus volcanism). Eight sections encompassing the K/Pg succession across the Mississippi Embayment were analyzed using biostratigraphic sampling of ammonites, dinoflagellates, and nannofossils. An upper Maastrichtian ammonite zonation is proposed as follows, from oldest to youngest:</span><i>Discoscaphites conradi</i><span> Zone, </span><i>D. minardi</i><span> Zone, and </span><i>D. iris</i><span> Zone. Our study documents that the ammonite zonation established in the Atlantic Coastal Plain (ACP) extends to the GCP. This zonation is integrated with nannofossil and dinoflagellate biostratigraphy to provide a framework to more accurately determine the age relationships in this region. We demonstrate that ammonites and dinoflagellates are more reliable stratigraphic indicators in this area than nannofossils because age-diagnostic nannofossils are not consistently present within the upper Maastrichtian in the GCP. This biostratigraphic framework has the potential to become a useful tool for correlation of strata both within the GCP and between the GCP, Western Interior, and ACP. The presence of the uppermost Maastrichtian ammonite </span><i>D. iris</i><span>, calcareous nannofossil </span><i>Micula prinsii</i><span>, and dinoflagellates </span><i>Palynodinium grallator</i><span> and </span><i>Disphaerogena carposphaeropsis</i><span> suggests that the K/Pg succession in the GCP is nearly complete. Consequently, the GCP is an excellent setting for investigating fine scale temporal changes across the K/Pg boundary and ultimately elucidating the mechanisms causing extinction.</span></p>
application/pdf
10.1016/j.cretres.2015.11.010
en
Academic Press
Upper Maastrichtian ammonite biostratigraphy of the Gulf Coastal Plain (Mississippi Embayment, southern USA)
article