Chronostratigraphic (“Wheeler”) Chart
of the Texas Gulf Coast Tertiary System
L. F. Brown, Jr., and R. G. Loucks
Bureau of Economic Geology, Jackson School of Geosciences,
The University of Texas at Austin, Box X, University Station, Austin, Texas 78713-8924
chronostratigraphic chart of the Tertiary
System of the Texas
Basin (~65 Ma to present) was constructed using public and in-house stratigraphic and paleontological
data. Sequence stratigraphic analysis was applied to the data. The authors
utilized outcrop and shallow subsurface lithostratigraphic information to identify the
nature of systems tracts, that is highstand, transgressive and lowstand facies and their
bounding surfaces: unconformities, flooding = condensed events, and transgressive surfaces.
These tracts were then adjusted to a vertical succession of ages (Ma) beginning
with the basal Paleocene using available, mostly published microfossil biochronozones
and ages of surfaces. Where no data existed we extrapolated between data points.
The chart presents a perspective of the time stratigraphy of depositional sequences
composing the Paleogene and Neogene sedimentary cyclicity of the extensively drilled
Cenozoic wedge in the Gulf Basin. The authors integrated ages of sequence stratigraphic
surfaces, paleontologic chronozones, and downdip development of systems tracts
from published sources. All data in a uniform sequence stratigraphic protocol based on
current understanding of the impact of cyclic relative changes of sea level on principally
siliciclastic depositional systems in the region since the end of the Cretaceous was honored.
The chronostratigraphic chart will provide a mechanism for others to critique and
modify with further data. Furthermore, to keep the chart as simple as possible, the authors
have avoided adding structural complexity, such as salt and shale structures,
faults, and other tectonic effects that are superimposed on the Tertiary succession.
AAPG Search and Discover Article #90069©2007 GCAGS 57th Annual Convention, Corpus Christi, Texas