2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 4
Presentation Time: 8:45 AM

Depositional Systems and Holocene Evolution of Baffin Bay, Texas

SIMMS, Alexander R.1, ARYAL, Niranjan2, MILLER, Lauren1, YOKOYAMA, Yusuke3 and MATSUZAKI, Hiroyuki3, (1)Boone Pickens School of Geology, Oklahoma State University, 105 NRC, Stillwater, OK 74074, (2)Schlumberger, 1515 Poydras Suite 2700, New Orleans, LA 70112, (3)Department of Earth and Planetary Sciences, Univ of Tokyo, 7-3-1 Hongo, Bldg#1, Bunkyo-ku, Tokyo, 113-0033, Japan, alex.simms@okstate.edu

Using over 65 km of high-resolution seismic profiles and 10 cores from Baffin Bay, Texas we present a depositional and evolutionary model for an estuary formed in a semi-arid climate. Baffin Bay is the flooded incised valley of San Fernando, Los Olmos, and Petronila Creeks. It is currently situated in a semi-arid climate and isolated from the open Gulf of Mexico by Padre Island. As a result, the salinities within Baffin Bay vary widely but average around 50-60 ppt. Baffin Bay initially flooded before 8 ka, most likely around 9.5 ka. During the early part of its Holocene history, it was less restricted and/or more humid than today as evidenced by oysters (Crassostrea virginica) and a well-developed fluvial system, neither of which are found in the bay system today. Around 8.0 ka, the estuary experienced a rapid landward expansion as evidenced by sharp contacts in marine cores and seismic profiles. This event most likely resulted from a small-amplitude global sea-level rise event associated with the drainage of Lake Agassiz-Ojibway. By ~5 ka, the estuary became more restricted and/or drier, similar to the conditions prevalent today. As a result of its isolation and semi-arid setting, the bay has developed some depositional elements different from the other estuaries of Gulf of Mexico over the last 5 ka. These include several “fetch-limited” barrier islands and spits composed almost exclusively of shell hash, serpulid worm-tube reefs, and prograding mud flats covered in algal mats.