Abstract Detail

Paleobotany

Baghai-Riding, Nina [1], Starnes, James [2], Axsmith, Brian [3], Hotton, Carol [4], Hunsucker, Myrtle [5].

Paleoenvironmental and Taphonomic Implications of a Palynological Sample from the Forest Hill Formation.

The early Oligocene Forest Hill Formation (Vicksburg Group) in eastern Smith County, Mississippi is of particular interest, as there are few such terrestrial units in North America. Bulk samples of fissile clay from this deltaic unit were collected by James Starnes and George Phillips. This formation contains a rich and diverse assemblage of well-preserved plant macrofossils, including palm fronds along the fissile bedding planes of fresh exposures. One palynological sample was acquired from the megafossil leaf site, which yielded a large quantity of diverse pollen, spores, and algal cysts suggestive of an oak-hickory-willow coastal forest bordering freshwater riverbanks. A few palynomorphs possibly were acquired from long-distance transport, but the majority of the palynomorphs are probably representative of the local vegetation because of the pristine preservation and absence of pyritization or other degradation. In a 300-point count, angiosperms comprised 59%, conifers 11.4 %, pteridophyte trilete spores 19 %, monolete spores 1.5 %, freshwater algal forms 9 % and dinoflagellates cysts and acritarchs 1.5% of the assemblage. Common pollen types include Aquifoliaceae (Ilexpollenites), Arecaceae (palms), Betulaceae (Alnus, Corylus), Chenopodiaceae, Cornaceae (Nyssa), Fabaceae, Fagaceae (Quercus, Siltaria) Juglandaceae (Carya, Engelhardtia, Momipites), Malvaceae (Tilia, Bombacacidites), Oleaceae (Fraxinus), Platanaceae (Platanus), Salicaceae (Salix), Ulmaceae (?Celtis, Ulmus), Liliacidites, Tetracolporites and the conifers Cupressaceae (Taxodiacidites) and Pinaceae (Pinus). Spores include Anemiaceae (Anemia), Cyatheaceae, Ophioglossaceae (Ophioglossum), Osmundaceae (Osmunda), Polypodiaceae, Sphagnaceae (Sphagnum), and the unknowns ?Dictyophyllum and Foveotriletes. A few unidentified dinoflagellates and freshwater algal cysts of Zygnemataceae (Schizosporis)and Maculatasporites also occur in the sample. This assemblage suggests a warm temperate terrestrial environment bordering a storm surge zone. In comparison, the Bucatunna Formation that directly overlies the Forest Hill unit, separated by a transgressive sequence of shallow marine fossiliferous limestone and marl, has similar angiosperm and gymnosperm pollen. The Bucatunna Formation, however, contains a higher diversity and quantity of dinoflagellates that marks the end of the marine transgression in the Vicksburg Group.

1 - Delta State University, Division Of Math And Sciences, Walters Hall Room 116A, Cleveland, MS, 38733, United States
2 - Mississippi Department of Environmental Quality, Office of Geology, P.O. Box 2279, Jackson, MS, 39225, USA
3 - Biology Department, 5871 USA Drive North, Room 124, Mobile, AL, 36688, United States
4 - National Museum of Natural History, Smithsonian Institution, 10th St. & Constitution Ave. NW, Washington, DC, 20560, USA
5 - Delta State University, Division of Math and Sciences, 1003 West Sunflower Rd., Cleveland, MS, 38733, USA

Keywords:
Oligocene
Bucatunna Formation
pollen
spores
palynomorphs.

Presentation Type: Poster
Session: P, Paleobotany Posters
Location: Virtual/Virtual
Date: Wednesday, July 29th, 2020
Time: 5:00 PM Time and date to be determined
Number: PPB002
Abstract ID:308
Candidate for Awards:None