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Lies Loncke Virginie Gaullier Laurence Droz Emmanuelle Ducassou Sébastien Migeon Jean Mascle 《Marine and Petroleum Geology》2009,26(5):633-646
The Nile deep-sea fan (NDSF), turbiditic system reaching a size of about 90,000 km2, has been investigated since 1998 by several geophysical methods (multibeam bathymetry, backscatter imagery, seismic data, 3–5 kHz echo-sounding). The analysis of this important data set evidenced that the NDSF is the locus of numerous multi-scale slope instabilities. Three main types of instabilities have been defined, mainly on the basis of their size or origin. (1) First type of instabilities related to the generalized gravity spreading of the Plio-Quaternary deep-sea fan on Messinian salt layers. This global spreading is accommodated by numerous localized slides. (2) Second type of instabilities correspond to giant mass movements probably triggered either by earthquakes, fluids, or climate and eustatic oscillations. Finally, (3) third type of instabilities correspond either to localized levee liquefactions or to thin-skinned slides on the steep slopes of the Eratosthenes seamount. The deposits generated by these slope movements greatly participate in the building of the NDSF. The characterization of these different instabilities, in a petroleum province as the NDSF, has important implications in terms of risk assessments when considering drilling operations. 相似文献
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Sbastien Garziglia Sbastien Migeon Emmanuelle Ducassou Lies Loncke Jean Mascle 《Marine Geology》2008,250(3-4):180-198
In the Nile deep-sea turbidite system (NDSTS), the province fed by the Rosetta branch of the Nile delta is characterised by the recurrent activity of gravity processes. Seven mass-transport deposits (MTDs) were recognised from the upper to the mid slope, downstream from imbricated scars (~ 30 km-long, ~ 200 m high) running along the shelf edge nearby the Rosetta canyon. Extending on surfaces between 200 and 5000 km2, with estimated volumes from 3 to 500 km3, these MTDs represent about 40% (up to 90% locally) of the total Pleistocene–Holocene sedimentary thickness. Three types of MTDs can be distinguished on the basis of their scale. Each has also a distinctive internal configuration and distribution within the Rosetta depositional setting. Age estimates of two MTDs point towards relationships between climate and submarine mass failures through sea-level changes, sediment supply, or a combination of both. Additionally, the presence of gas in the sediment and earthquake shaking may have concurred to trigger large-scale failures on the low slope angles (1°–2°) of the Rosetta area. 相似文献
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Morphology and structure of a landslide complex in an active margin setting: The Waitawhiti complex, North Island, New Zealand 总被引：1，自引：0，他引：1
Aurlien Lacoste Lies Loncke Frank Chanier Julien Bailleul Bruno C. Vendeville Geoffroy Mahieux 《Geomorphology》2009,109(3-4):184-196
Multi-scale gravitational instabilities are widespread in the Coastal Ranges of the North Island of New Zealand. We document here a detailed analysis of the Waitawhiti landslide complex, located in the core of the Tawhero syncline, and investigate the potential landslides triggering factors in the area. Four contiguous large slides form the Waitawhiti complex. These slides involve fine-grained Miocene sandstones and massive fractured siltstones. Sliding occurs mostly along nearly horizontal strata. All slides are bounded laterally and/or distally by deep-incised valleys. Three gas seeps evidencing thermogenic gas release have been discovered in the vicinity of the slides. We propose that river incision, continuously removing distal buttresses, is the main destabilizing factor in the area. However, additional factors, such as tectonic activity and intense rainfall, cannot be excluded. We also propose that fluid overpressure, reducing the effective shear strength at the base of low-permeability layers, may have influenced the triggering of landslides in the Waitawhiti area. 相似文献
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B. Delouis J. Déverchère V. Melnikova N. Radziminovitch L. Loncke C. Larroque J. F. Ritz V. San'kov 《地学学报》2002,14(6):491-500
ABSTRACT The precise nature of the transition between the present-day compressional tectonics in central Mongolia and extensional deformation in the central Baikal rift has still to be determined. For that purpose we have built a comprehensive earthquake focal mechanism data base for the Mongolia – southern Siberia area, from which we map the variations of the stress field. We focus our detailed investigations on the largest seismic event in the transition zone, the 1950 (Mw 6.9) Mondy earthquake, for which several discordant focal mechanisms have been proposed. Using a new approach in source inversion, we resolve the focal mechanism (left-lateral strike slip type on a steep south-dipping fault) and depth (14 ± 3 km) of the Mondy earthquake with a satisfactory accuracy. This seismological information, combined with the geological observations, allows us to decipher the connections between the 1950 mainshock, the local stress tensor and the active faults, which strongly suggest a partitioning of the deformation between two faults, namely the Mondy and Ikhe–Ukghun faults. 相似文献
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Morphostructure of the Egyptian Continental Margin: Insights from Swath Bathymetry Surveys 总被引：1，自引：0，他引：1
Jean Mascle Olivier Sardou Lies Loncke Sébastien Migeon Laurent Caméra Virginie Gaullier 《Marine Geophysical Researches》2006,27(1):49-59
In the Eastern Mediterranean, offshore Egypt, the Nile continental margin is characterized by a large deep water turbiditic
system known as the Nile Deep Sea Fan. This post-Miocene terrigenous construction covers an approximately 10 km-thick sedimentary
pile, including 1–3 km of Messinian salt layers. Systematically collected swath bathymetric data proved to be the most powerful
tool to discover, describe and study many sea floor features of this sedimentary construction which reflects competition between
active tectonic, sedimentary, and geochemical processes. Gravity tectonics, triggered by underlying mobile salt layers, construction
of channel-levee systems, the passage of turbidite flows, sedimentary slope failures at various scales, massive mud expulsions
and fluid seepages are all interfering to shape the Nile Deep Sea Fan seabed. 相似文献
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In the Nile deep‐sea fan, thin‐skinned deformation detaching on a layer of Messinian salt has generated an upslope to downslope progression from growth faults, to polygonal minibasins bounded by salt ridges, to buckle folds. Such progression is common in salt‐bearing passive margins, where gravity spreading of the salt–sediment system causes proximal thin‐skinned extension on the shelf and upper slope, and distal contraction along and in front of the lower slope. In the Eastern Nile deep‐sea fan, this structural progression seems to be restricted to a corridor bounded by NW–SE‐trending lineaments more than 200 km in length. These are associated with salt ridges and record strike–slip movements. In the absence of a large grid of deep‐penetrating seismic data accurately imaging the basement, different likely hypotheses have been advanced about the origin of this corridor: (1) it may result from possible deep‐seated tectonics related to the Rift of Suez, combined with salt‐related deformation or, (2) by complex interaction between the overburden's gravity spreading and pre‐existing pre‐Messinian paleo‐topographic features, particularly the possible buttressing effect of a seamount located North of the eastern Nile deep‐sea fan. In order to understand how this corridor could have been generated, we used a series of physical experiments to test the effect on three‐dimensional spreading of a sediment lobe of the following parameters: (1) active, crustal, oblique extension, (2) a dormant subsalt graben, (3) a passive buttress, such as a seamount and (4) complex paleo‐topographic features along the Egyptian margin affecting initial salt distribution. These experiments show that the presence of a distal buttress, combined with a complex Messinian topography best explain the complex deformational pattern observed in the eastern Nile deep‐sea fan. 相似文献
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