Journal ArticleDOI
Water escape structures in coarse-grained sediments
TLDR
Water escape structures as discussed by the authors represent both the direct rearrangement of sediment grains by escaping fluids and the deformation of hydroplastic, liquefied, or fluidized sediment in response to external stresses.Abstract:
Three processes of water escape characterize the consolidation of silt-, sand-and gravel-sized sediments. Seepage involves the slow upward movement of pore fluids within existing voids or rapid flow within compact and confined sediments. Liquefaction is marked by the sudden breakdown of a metastable, loosely packed grain framework, the grains becoming temporarily suspended in the pore fluid and settling rapidly through the fluid until a grain-supported structure is re-established. Fluidization occurs when the drag exerted by moving pore fluids exceeds the effective weight of the grains; the particles are lifted, the grain framework destroyed, and the sediment strength reduced to nearly zero. Diagenetic sedimentary structures formed in direct response to processes of fluid escape are here termed water escape structures.
Four main types of water escape structures form during the fluidization and liquefaction of sands: (1) soft-sediment mixing bodies, (2) soft-sedimsnt intrusions, (3) consolidation laminations, and (4) soft-sediment folds. These structures represent both the direct rearrangement of sediment grains by escaping fluids and the deformation of hydroplastic, liquefied, or fluidized sediment in response to external stresses.
Fundamental controls on sediment consolidation are exerted by the bulk sediment properties of grain size, packing, permeability, and strength, which together determine whether consolidation will occur and, if so the course it follows, and by external disturbances which act to trigger liquefaction and fluidization. The liquefaction and fluidization of natural sands usually accompanies the collapse of loosely packed cross-bedded deposits. This collapse is commonly initiated by water forced into the units as underlying beds, especially muds and clays, consolidate. The consolidation of subjacent units is often triggered by the rapid deposition of the sand itself, although earthquakes or other disturbances are probably influential in some instances.
Water escape structures most commonly form in fine- to medium-grained sands deposited at high instantaneous and mean sedimentation rates; they are particularly abundant in cross-laminated deposits but rare in units deposited under upper flow regime plane bed conditions. Their development is favoured by upward decreasing permeability within sedimentation units such as normally graded turbidites. They are especially common in sequences made up of alternating fine-(clay and mud) and coarse-grained (sand) units such as deep-sea flysch prodelta, and, to a lesser extent, fluvial point bar, levee, and proximal overbank deposits.read more
Citations
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Journal ArticleDOI
Deep-Water Sandstone Facies and Ancient Submarine Fans: Models for Exploration for Stratigraphic Traps
TL;DR: In this article, five main facies of deep-water clastic rocks can be defined: classic turbidites, massive sandstones, pebbly sandstone, conglomerates, and debris flows (with slumps and slides).
Book
Pyroclastic density currents and the sedimentation of ignimbrites
TL;DR: Bursik et al. as mentioned in this paper presented a conceptual framework for investigating how ignimbrites are deposited, integrating the results of field-based studies, laboratory experiments and numerical modelling, including work on clastic sedimentologym and industrial particle transport.
Journal ArticleDOI
Subglacial till: Formation, sedimentary characteristics and classification
TL;DR: The major subglacial till forming processes as presently understood by glacial researchers and define the parameters within which tills are produced and reconcile them with sedimentary end members as discussed by the authors.
Journal ArticleDOI
50 years of the turbidite paradigm (1950s—1990s): deep-water processes and facies models—a critical perspective
TL;DR: In this paper, a slope model is proposed that is a debris-flow dominated setting with both non-channelized and channelized systems, based on fluid rheology and flow state.
Journal ArticleDOI
Use of liquefaction-induced features for paleoseismic analysis - An overview of how seismic liquefaction features can be distinguished from other features and how their regional distribution and properties of source sediment can be used to infer the location and strength of Holocene paleo-earthquakes
TL;DR: In the field of geotechnical analysis of sediment deformation, the most important criterion is that a seismic liquefaction origin requires widespread, regional development of features around a core area where the effects are most severe.
References
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Journal ArticleDOI
The River Klarälven a Study of Fluvial Processes
TL;DR: The River Klaralven a Study of Fluvial Processes as discussed by the authors is a study of fluvial processes in the literature, which is related to our work.
Journal ArticleDOI
Experiments on density and turbidity currents: iii. deposition of sediment
TL;DR: Turbidity currents were formed by releasing suspensions of plastic beads (density 152, median diameter 1.8mm) from a lock into a horizontal water-filled flume as discussed by the authors.
Book ChapterDOI
Primary Sedimentary Structures Formed by Turbidity Currents and Related Resedimentation Mechanisms
Journal ArticleDOI
I.—Experiments in Geology
TL;DR: Experimental Geology as mentioned in this paper assesses the value of past experiments in geology and presents some examples from my own research in an attempt to vindicate this method, but the majority of earth scientists appears to be highly suspicious of, or actually opposed to, experimental attack on their problems.