| Summary: | The Eocene-Oligocene (E-O) transition is a key interval in geological history because it
marks a major change in Earths climate and because these strata are also popular oil targets in
the Gulf Coast.
E-O sequences in Alabama are stratigraphically complex. The St. Stephens Quarry (SSQ)
in Alabama is one of the few accessible quarries along the Gulf Coast where the E-O boundary
is visible in outcrop. Despite the abundance of research projects conducted in the SSQ, many
controversies still surround the E-O boundary placement and correlation to the Global Stratotype
in the Massignano section in Italy that is based on the extinction of the Hantkeninidae family.
The lack of Hantkenina sp. (Miller et. al., 2008) in a core from near the SSQ and the stratigraphy
there contribute to the controversy in boundary placement.
To supplement the rarity of foraminifera biomarkers in the section, I present the results
of a high-resolution palynological study of the St. Stephens Quarry in Alabama, to help better
constrain the boundary placement and associated environmental changes. The new data provide
1) an alternate biostratigraphic zonation and locate the E-O boundary based on organic-walled
microfossils to increase biostratigraphic control in the Gulf Coast region, 2) a way to supplement
and assist biosteering when foraminifera are not present, and 3) new environmental data
(sea-surface conditions and climate) across the boundary. By comparing SSQs palynomorph
assemblages to worldwide stratigraphic charts we have established that the E-O boundary occurs
within the transition between the Shubuta marl and the Bumpnose limestone (between 3.60-
3.65m depth).
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