Evidence for Active Growth Faulting in the Terrebonne Delta Plain, South Louisiana: Implications for Wetland Loss and the Vertical Migration of Petroleum

¹ Baker Atlas Geoscience, Houston, TX 77073
² Louisiana State University, Coastal Studies Institute, Baton Rouge, LA 70803
³ Argonne National Laboratory, Argonne, IL 60439
⁴Baker Atlas Geoscience, Houston, TX 77073

Gerald J. Kuecher is a Sedimentologist for Baker Atlas GeoScience in Houston where he serves as Coordinator of Deepwater Reservoir Characterization, Image Log Analyst, and Field Studies Consultant. He has 11 years experience in exploration and production companies, and two years experience in the service industry. He is an instructor for Oil and Gas Consultants, Inc., and teaches two course offerings. He has published on such diverse topics as deep water sediments, deltaic sediments, tidal sediments, subsidence, faulting, fluid flow, and on the application of high resolution seismic electromagnetics, and ground-penetrating technologies to sedimentology.

Ingeborg Matthews works at Baker Atlas in the capacity of Log Analyst. Her specialties include software support and database management. She is in her final year of a Computer Science degree at the University of Houston.

Michael D. Thompson received his B.S. (1985) in geology from Southern Illinois University, and an M.S. (1989) and Ph.D. (1997) in geology from Northern Illinois University. He is currently employed at Argonne National Laboratory where his research interests focus on the application of geophysical techniques to environmental problems. Particular emphasis is placed on using geophysics in cantonment and industrial areas. He is an active member of the Environmental and Engineering Geophysical Society and the American Geophysical Union.

Harry H. Roberts is Director of Coastal Studies Institute, and a member of the Department of Oceanography and Coastal Sciences at Louisiana State University. He is recognized on an international level for sedimentological and sidimentary process research in both terrigenous clastic and carbonate depositional systems. His experience in deltaic and associated marine sediments includes studies of delta plains to submarine fans. He is the author of over 130 scientific papers related to research conducted in the U.S. as well as Africa, Australia, Indonesia, South America, Central American, and many sites in the Caribbean. Most of these studies have incorporated acquisition and interpretation of high-resolution geophysical data in conjunction with sediments, cores, borings, and bottom grabs. He is an advisory editor for two international journals, and has had over 30 years research experience. During this period, he has been a consultant for most major oil companies that operate in the U.S. Gulf Coast. He has also taught continuing education courses both in the U.S. and in several foreign countries, including Australia, Indonesia, Singapore, and sites in the Caribbean. His current research deals with development of an understanding of the surficial geology of northern Gulf of Mexico continental slope and continuing work on problems associated with the deltaic coasts of Louisiana.

ABSTRACT

Two regional growth faults, the Golden Meadow Fault and the Lake Hatch Fault, were mapped in Terrebonne and Lafourche Parishes, Louisiana, utilizing over 3000 line kilometers of seismic data. The subcropping location of these faults identify major vegetation biozonations, new areas of wetland loss, and the position of transgressive lakes. The proposed mechanism governing these fault-related manifestations of subsidence involves the venting of fluid (and gas) from geopressured shales vertically up fault planes. Saline fluids and gases exiting a basin via growth faults provide accommodation space at depth, resulting in active, fault-induced subsidence in the down-thrown block. By contrast, areas along the fault trend where no fluids or gases were migrating would not result in an increase of accommodation space and would be considered inactive regarding faultinduced subsidence. The model that emerges is a growth fault trace that does not act in concert but more closely resembles a key-stepping system with sections alternating between active and inactive. These findings are relevant to the role of growth faults in subsidence-related coastal land loss and the vertical migration of hydrocarbons.