The Character and Genesis of Submarine Mass-Transport Deposits: Insights from Outcrop and 3D Seismic Data
Published:January 01, 2011
Henry W. Posamentier, Ole J. Martinsen, 2011. "The Character and Genesis of Submarine Mass-Transport Deposits: Insights from Outcrop and 3D Seismic Data", Mass-Transport Deposits in Deepwater Settings, R. Craig Shipp, Paul Weimer, Henry W. Posamentier
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Extensive deep-water mass-transport deposits are observed in both slope and basin-floor settings. A detailed understanding of mass-transport deposits, in terms of emplacement processes, depositional products, and their stratigraphic and geographic distribution, is vital because they can constitute a significant portion of the stratigraphic section in deep-water settings. In addition, mass-transport deposits can play a significant role in hydrocarbon exploration, inasmuch as they can constitute seal, reservoir, and possibly source facies under the right circumstances.
Different data types bring to light different aspects of mass-transport deposits. This paper focuses on insights derived from seismic and outcrop data. Overall geometries and architecture of mass-transport deposits are readily observable in 3D seismic data; however, features below seismic resolution that are vital for process and lithologic understanding need to be observed in outcrop. Integrating observations across a broad range of scales by linking seismic and outcrop observations constitutes an effective way of improving our understanding of when and where mass-transport deposits are likely to form. In addition, this linkage sheds light on details of internal architecture that commonly characterizes these deposits.
Mass-transport deposits can comprise sheets, lobes, and channel fills, and can reach 150 m or more in thickness. Greater thicknesses are observed where successive flows are amalgamated. This paper documents both internal architectural or stratigraphic as well as external geomorphic attributes of such deposits, as expressed in outcrop and imaged by 3D seismic data.
Recognition of mass-transport deposits in outcrop is based on identification of bedding deformed by synsedimentary processes, with deformation ranging from minimal redistribution of large slide blocks to complete disaggregation typical of debris-flow deposits. On seismic data, mass-transport deposits can be recognized by certain geomorphologic as well as stratigraphic distinguishing characteristics: basal linear grooved and scoured surfaces, hummocky relief at the top, and internal chaotic to transparent seismic facies, with internal thrust faulting common.
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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.