GSA Annual Meeting in Phoenix, Arizona, USA - 2019

Paper No. 235-6
Presentation Time: 9:15 AM


SMITH, Vann, Department of Geology and Geophysics, Louisiana State University, E-235 Howe-Russell, Baton Rouge, LA 70803, WARNY, Sophie, Department of Geology and Geophysics, and Museum of Natural Science Baton Rouge, USA, Louisiana State University, E235 Howe-Russell Geoscience Complex, Baton Rouge, LA 70803, VAJDA, Vivi, Swedish Museum of Natural History, Dept of Palaeobotany, Box 50001, Stockholm, S-104 05, Sweden, VELLEKOOP, Johan, Department of Earth and Environmental Sciences, University of Leuven, Naamsestraat 22, 3000, Leuven, 3000, Belgium, JARZEN, David M., Paleobotany and Paleoecology, Cleveland Museum of Natural History, 1 Wade Oval Drive, University Circle, Cleveland, OH 44106 and DEMCHUK, Thomas D., RPS, 20405 Tomball Parkway, Suite 200, Houston, TX 77070

At the end of the Cretaceous Period, a large extraterrestrial object collided with the Earth and created the Chicxulub impact structure in the Yucatán Platform. International Ocean Discovery Program (IODP) Expedition 364 drilled into the peak ring of the Chicxulub impact crater, recovering a Paleocene to Early Eocene stratigraphic section that was deposited above the impact breccia. The post-impact section was sampled for terrestrial palynological analysis, yielding a high-resolution record of Danian to Ypresian pollen and spores. IODP 364 provides the first Paleocene and Ypresian terrestrial palynological assemblage for the Yucatán Peninsula, the Caribbean, and Central America, except for a few studies in mainland Mexico. Although the abundance of pollen and spores was very low in the mainly carbonate rocks of the Paleocene, abundance increased in the more organic-rich shale layers of the PETM (Paleocene-Eocene Thermal Maximum). Pollen and spore abundance and diversity in the later Ypresian were variable, but generally increased upsection, with high abundance and excellent preservation in several samples. The Paleocene palynological record from IODP 364, although limited by low abundance, provides the first record of long-term floral recovery from the end-Cretaceous mass extinction inside the impact crater. The high abundance and good preservation of pollen and spores in the PETM and later Ypresian sections indicate a proximal terrestrial source from lowland tropical forests and mangrove swamps in the Yucatán Platform to the south, with some components of the pollen and spore assemblage suggestive of montane or cloud forest, probably from more distal mountainous areas in mainland Mexico.