Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Stratigraphy and Internal Architecture of the Wave-Dominated Gum Hollow Delta, Nueces Bay, Texas: Implications for Architecture Scaling and Recording Paleo-Storminess in the Northwestern Gulf of Mexico
(1) Marine Science, Texas A&M University at Galveston, Galveston, TX.
(2) Oceanography, Texas A&M University at Galveston, Galveston, TX.
(3) Environmental Science, Texas A&M University - Corpus Christi, Corpus Christi, TX.
Gum Hollow Delta is a small micro-tidal, aggradational to slightly progradational, wave-dominated delta that built into Nueces Bay over the past 70 years. Gum Hollow Delta formed episodically due to high runoff and increased discharge in Gum Hollow Creek and temporarily elevated sea level during major tropical cyclones. The delta is 600 m in dip length, 1000 m in strike width, and 1.6 m in thickness. Gum Hollow Delta serves as a modern analog for larger wave-dominated deltas.
Over 50 vibracores were taken along 4 dip transects and 2 strike transects to delineate the internal stratigraphy and heterogeneity of the delta. The delta consists of 7 bedsets (i.e., equivalent to parasequences in ancient deltas) representing deltaic growth events. Internal stratigraphic correlations were constrained by the identification of significant widespread flooding surfaces in cores and by 137Cs geochronology. Flooding surfaces formed as storm surges produced short-term base-level rises in Nueces Bay, which were followed by rapid sedimentation events. Tropical cyclones such as the 1945 Hurricane and the 1949 Hurricane and named hurricanes Alice, Carla, Beulah, Celia, Allen, and Bret produced significant base-level rises and deltaic depositional events (parasequences). Distributary channel avulsions are also correlative with major tropical cyclones. Comparison of the timing of the deposition of stratigraphic units, constrained by 137Cs geochronology and historical aerial photographs, and the historical record of storms in the Gulf of Mexico indicate that the Gum Hollow Delta preserves a 70-year record of paleo-storminess.
Dip length/thickness and strike width/thickness aspect ratios of Gum Hollow Delta parasequences are similar to aspect ratios determined for large, micro-tidal, wave-dominated deltaic parasequences, such as those exposed in the Cretaceous Upper Ferron Sandstone Last Chance Delta in the Western Interior Basin in Utah, even though the Gum Hollow Delta is 1/50th the size of the Last Chance Delta. This suggests that the internal architecture and heterogeneity of small-scale modern deltas, which are easily analyzed in great 3-D detail, can be scaled to assist in the interpretation of the internal architecture and heterogeneity of larger subsurface deltas or 2-D exposures of outcrop deltas.