Late Neogene to Recent Seafloor Instability on the Deep Pacific Margin of the Antarctic Peninsula
Published:January 01, 2011
Valentina Volpi, David Amblas, Angelo Camerlenghi, Miquel Canals, Michele Rebesco, Roger Urgeles, 2011. "Late Neogene to Recent Seafloor Instability on the Deep Pacific Margin of the Antarctic Peninsula", Mass-Transport Deposits in Deepwater Settings, R. Craig Shipp, Paul Weimer, Henry W. Posamentier
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Sediment mass transport in the Pacific margin of the Antarctic Peninsula is strongly influenced by its peculiar tectonic and sedimentary evolution. Analysis of swath bathymetry and multichannel seismic reflection data shows that this setting reflects the passage from an active to a passive margin, and the transition from river-dominated to glacier-dominated sedimentation. Only contouritic sedimentation persisted throughout the late Neogene on the continental rise, while rapid progradation of steep wedges composed of glacial diamicton occurs on the slope. Gravitational instability and mass-transport processes, which occur on the continental rise, appear to relate to physical properties of contourite sediments deposited in this high-latitude setting.
Other than minor erosional gullies on the upper slope, there is no evidence of major incisions such as channels, canyons, or slide scars on a steep continental slope (averages 13°). This situation results from high shear strength of the slope-forming diamicton delivered by grounded ice sheets. Short-run-out mass failures were the main sediment transport process to the slope. Turbidity currents, most likely originated by downslope evolution of mass flows, were able to generate large deep-sea channel systems at the base of the continental slope.
On the continental rise, relatively good sorting and a high accumulation rate of sediments forming sediment drifts favored slope failure even on gentle slopes. Coalescent headscarps that form the drift crest were produced by undercutting of steeper flanks of drifts. This process formed the walls of turbidity-current channels, flowing in low-relief areas between drifts. Failure along stratal weak layers on the gentle sides of sediment drifts produced either relatively small, concave slide scars in the margin-proximal drift or long, rectilinear scars in distal locations.
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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.