Palynology and palynofacies analyses of the Gray Fossil Site, eastern Tennessee: Their role in understanding the basin-fill history

The Gray Fossil Site (GFS) includes multiple karst sub-basins that are filled with lacustrine sediments. Early paleontologic work on one of the sub-basins (GFS-2) indicates a late Miocene/early Pliocene age based on an assemblage of well-preserved vertebrate fossils. However, detailed palynological analysis of the 38.7 m deep GFS-1 core recovered from another sub-basin indicates an older age. The presence of Caryapollenites imparalis, C. inelegans and C. prodromus association suggests a Paleocene to Eocene age for the GFS-1 core section. This age is also supported by the absence of pollen of the Poaceae, the grass family that is not commonly present until the Neogene. Age constraints from palynologic data suggest that the GFS has a more complex basin-fill history than previously suspected, and that multiple depo-centers within the basin may have been periodically active through the Cenozoic. Palynofacies analysis of the GFS-1 core indicates that phytoclasts and opaques are the most abundant organic constituents and have diluted both the palynomorph population and amorphous organic matter. Two possible scenarios can account for this observation: 1) an oxidizing depositional paleoenvironment; and 2) a localized high flux of charcoal following wildfires and subsequent increased runoff.

Research highlights
► Palynology, palynofacies, and geochemical analyses of the Gray Fossil Site (GFS).
► The GFS contains asynchronous sub-basins of variable basin-fill histories.
► GFS−1 sub-basin is dated Paleocene−Eocene based on palynomorphs.
► GFS−1 flora is primarily Oak–Hickory–Pine Woodland, with an herb/shrub understory.
► Wildfires may have been an important element in the GFS−1 ecosystem.