Fluvial Response to Growth Faulting in the Pearl River Delta, Louisiana

Stephen A. Prosser, Kevin M. Yeager, and Kimberly J. Schindler
University of Kentucky, Lexington, KY

The Pearl River Delta (PRD) in southeastern Louisiana is an actively deforming deltaic complex displaying surface and near-surface evidence of active growth faulting. Active growth faults in these environments are rarely identified at the surface, in part because the downthrown blocks often experience increased rates of sediment deposition leading to an obscured and low-relief, or entirely absent surface expression. Faulting can be expressed in fluvial systems as changes in channel gradient, which often result in coincident changes in channel sinuosity, migration rates, planform deflections, and/or ponding features within the deformed zone. The study area for this project is focused on a tortuous meander bend of the West Pearl River (WPR). The nature of the meander bend suggests the likely presence of two, non-laterally extensive growth faults bounding the north and south bends of the tortuous meander. This research intends to test the hypotheses that 1.) Active near-surface growth faulting is constraining the tortuous meander bend of the WPR and 2.) Growth faults, where present and active, are strongly-coupled to channel meander planform changes and marsh accretion rates in the PRD. The proposed hypotheses will be supported by the use of shallow (to ~10m) litho- stratigraphy, a suit of constant fallout radionuclides (²¹⁰Pb, ¹³⁷Cs, and ⁷Be) to analyze marsh accretion rates, and optical surveying to identify elevation changes across faults. Aerial Imagery and seismic (CHIRP) data will also be collected to model channel migration over time, similar to the WPR, throughout the PRD, as well as in-channel gradient changes of the WPR.

AAPG Search and Discovery Article #90181©2013 AAPG/SEG Rocky Mountain Rendezvous, University of Wyoming, Laramie, Wyoming, September 27-30, 2013