Seabed Slope Processes in Deep Water Continental Margin, Northwest Gulf of Mexico

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9530396 Silva Natural resources recovery, including offshore oil and gas is the most important economic activity in the United States Exclusive Economic Zone. Many technical constraints must be faced as the industry moves toward sites on the continental slope and rise where seabed processes are complex. The objective of this research project is to understand the fundamental linkages between engineering properties of slope sediments, environmental forcing functions, and downslope processes; and to develop the capability of predicting the range of seabed processes. The program is theoretical as well as an integrated combination of field, laboratory, and modeling efforts. A corridor 2000m wide by 100 nm long, of the seabed in the northwest Gulf of Mexico has been selected extending from water depths of 1000 to 3000m. This corridor encompasses a wide range of seabed processes including mass wasting and creep, faulting, diapirism, sediment flows, and related processes such as fluid expulsion and depressions (basins) associated with halokinesis. The field work during the first year entails two research cruise expeditions: the first to obtain detailed acoustic subbottom information and side-scan sonar seafloor images within the corridor and the second to obtain large-diameter undisturbed core samples to depths of 25 to 30m subbottom and to conduct in situ geotechnical tests. The comprehensive laboratory testing program focuses on determining the pertinent geotechnical properties and parameters necessary for the analysis/modeling portion of the research. Essentially all the instrumentation is available for the experimental studies. The laboratory program will include determination of constitutive models to characterize the engineering behavior of the various sediments from very slow deformations (creep), static stress strain properties, and flow properties. The material models and parameters will then be incorporated in available computer models to charac terize and study the full range of seabed processes that are encountered within the corridor site. The expected result will be the ability to predict the range of seabed processes at work on the continental slope of the Gulf of Mexico. ***