ABSTRACT: Subsurface
Sequence
Stratigraphic
Analysis
of the Eocene-Lower Oligocene of Alabama
KLEIN, ANDRE C., GERALD R. BAUM, and PETER R. VAIL , Department of Geology and Geophysics, Rice University, Houston, TX; PETER R. THOMPSON, Computational Biochronology, Plano, TX
South Alabama contains world-class outcrops of Eocene and Oligocene strata that have been the object of intense scrutiny over the past several years. Despite such thorough examination, these outcrops have failed to assuage controversy as to the nature of the Eocene/Oligocene (E/O) boundary in this region. Some workers have made this faunal boundary coincident with a![Previous Hit](/images/arrow_left.gif)
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A grid of geophysical wireline logs (SP and resistivity) has been assembled and
digitized in the area of interest to examine the nature of the E/O boundary on a seismic
scale. The log
data are calibrated to lithology and biostratigraphy using two
stratigraphic test cores. Preliminary results show the E/O boundary occurs in a relatively
fine-grained interval, stratigraphically below a surface of onlap (
sequence
boundary).
In addition, these well
log
data have been useful in analyzing other controversial
stratigraphic intervals, such as the Lisbon Formation, in the subsurface of Alabama.
Preliminary results, again calibrated to test cores, suggest the presence of at least
three regional coarsening upward cycles within the Lisbon. One of these cycles may
represent the Doby's Bluff tongue of the Kosciusko Formation. It is hoped that large-scale
stratal
analysis
will clear up these lingering controversies.
AAPG Search and Discovery Article #90908©2000 GCAGS, Houston, Texas