3-D Seismic Stratigraphic Interpretation of Quaternary Mass-Transport Deposits in the Mensa and Thunder Horse Intraslope Basins, Mississippi Canyon, Northern Deep Gulf of Mexico, U.S.A.
Published:January 01, 2011
Jorge Diaz, Paul Weimer, Renaud Bouroullec, Geoff Dorn, 2011. "3-D Seismic Stratigraphic Interpretation of Quaternary Mass-Transport Deposits in the Mensa and Thunder Horse Intraslope Basins, Mississippi Canyon, Northern Deep Gulf of Mexico, U.S.A.", Mass-Transport Deposits in Deepwater Settings, R. Craig Shipp, Paul Weimer, Henry W. Posamentier
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Abstract: The stratigraphic evolution of the Quaternary mass-transport deposits (MTDs) in the Mensa and Thunder Horse intraslope basins, Mississippi Canyon, northern deep Gulf of Mexico, was interpreted based on based on 378 square miles (970 square km) of 3-D seismic data in water depths ranging from 5300 to 6500 feet (1617 to 1983 m). Seven depositional sequences were defined in the study area between 1.3 Ma to the present. Allochthonous salt systems had bathymetric expression and influenced sediment thickness and location of depositional systems. Six MTDs are present in five of the depositional sequences. MTDs overlie erosional boundaries—up to 30 m of the underlying section has been eroded at the base of the deposits. These deposits consist primarily of chaotic, rotated, and thrusted seismic reflections. They vary in size and areal distribution from elongated to more equidimensional.
The oldest MTD is in sequence 1, overlies the 1.3 Ma condensed section, and underlies a series of five east-trending channels. This MTD has an easterly trend and represents the initial deposition after a major reorganization of the slope system. In the underlying Miocene-lower Pleistocene sequences, channels trended from the northwest to southeast. Sequences 2 and 3 consist of seven additional channels that trend primarily from west to east. The second MTD is present in sequence 3, trends to the southeast, and truncates four channels. A series of stacked condensed sections (ca. 0.6 to 0.08 Ma) form a thin unit and separate sequences 3 and 4. Sequence 4 consists primarily of hemipelagic and overbank deposits. Four MTDs are present in the sequences 5-7. Multiple sets of these deposits have channelized into and stacked on one another. These MTDs appear to have been sourced primarily from the west, similar to the channels in the underlying sequences.
This case study illustrates the many variations in MTDs that are present in the same intraslope setting. These variations can occur in their size, shape, thickness, seismic facies, the amount of erosion at their base, and their timing of formation within different positions of sea level.
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Mass-Transport Deposits in Deepwater Settings
Historically, submarine-mass failures or mass-transport deposits have been a focus of increasingly intense investigation by academic institutions particularly during the last decade, though they received much less attention by geoscientists in the energy industry. With recent interest in expanding petroleum exploration and production into deeper water depths globally and more widespread availability of high-quality data sets, mass-transport deposits are now recognized as a major component of most deep-water settings. This recognition has lead to the realization that many aspects of these deposits are still unknown or poorly understood. This volume contains twenty-three papers that address a number of topics critical to further understanding mass-transport deposits. These topics include general overviews of these deposits, depositional settings on the seafloor and in the near-subsurface interval, geohazard concerns, descriptive outcrops, integrated outcrop and seismic data/seismic forward modeling, petroleum reservoirs, and case studies on several associated topics. This volume will appeal to a broad cross section of geoscientists and geotechnical engineers, who are interested in this rapidly expanding field. The selection of papers in this volume reflects a growing trend towards a more diverse blend of disciplines and topics, covered in the study of mass-transport deposits.