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A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of the strain rate and the stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for the prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and step shear rate tests is examined. The model requires four empirical parameters. A methodology is presented for obtaining these parameters and power law functions are given for their calculations for a limited rest time of 3000 s. The ability of the model to reproduce the rheological behavior that clay-rich suspensions exhibit under both stress and strain controlled conditions is examined using rheometry tests.

A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of strain rate and stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and step shear rate tests is examined. The model requires four empirical parameters. A methodology is presented for obtaining these parameters and power law functions are given for their calculations for a limited rest time of 3000 seconds. The ability of the model to reproduce the rheological behavior that clay-rich suspensions exhibit under both stress and strain controlled conditions is examined using rheometry tests.

A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of strain rate and stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and step shear rate tests is examined. The model requires four empirical parameters. A methodology is presented for obtaining these parameters and power law functions are given for their calculations for a limited rest time of 3000 seconds. The ability of the model to reproduce the rheological behavior that clay-rich suspensions exhibit under both stress and strain controlled conditions is examined using rheometry tests.

A new viscoelastic constitutive model for subaqueous clay-rich gravity flows is presented. It is explained that for the materials which exhibit a minimum in their strain controlled flow curves the structure parameter must be a symmetric function of strain rate and stress. Therefore, the destruction of structure within the material is modeled using the dissipation energy. An expression for the elastic strain of the flowing structure is derived. The final set of equations can reproduce the viscosity bifurcation that clay suspensions may exhibit under a given load. This is explained to be important for prediction of the run-out distance of clay-rich gravity flows. The ability of the model to reproduce the general response of pasty materials to step stress and step shear rate tests is examined. The model requires four empirical parameters. A methodology is presented for obtaining these parameters and power law functions are given for their calculations for a limited rest time of 3000 seconds. The ability of the model to reproduce the rheological behavior that clay-rich suspensions exhibit under both stress and strain controlled conditions is examined using rheometry tests.

This study presents a classification for subaqueous clay-laden sediment gravity flows. A series of laboratory flume experiments were performed using 9%, 15%, and 21% sediment mixture concentrations composed of sand, silt, clay, and tap water, on varying bed slopes of 6°, 8°, and 9.5°, and with discharge rates of 10 and 15 m3/hr. In addition to the characteristics of the boundary and plug layers, which have been previously used for the classification of open-channel clay-laden flows, the newly presented classification also incorporates the treatment of the free shear layer. The flow states within the boundary and free shear layers were established using calculation of the inner variable, self-similarity considerations, and the magnitude of the apparent viscosity. Based on the experimental observations four flow types were recognized: (1) a clay-rich plug flow with a laminar free shear layer, a plug layer, and a laminar boundary layer, (2) a top transitional plug flow containing a turbulent free shear layer, a plug layer, and a laminar boundary layer, (3) a transitional turbidity current with a turbulent free shear layer, no plug layer, and a laminar boundary layer, and (4) a fully turbulent turbidity current. A connection between the emplaced deposits and the relevant flow types is drawn and it is shown that a Froude number, two Reynolds numbers, and a dimensionless yield stress parameter are sufficient to associate an experimental flow type with a natural large-scale density flow.

This study presents a classification for subaqueous clay-laden sediment gravity flows. A series of laboratory flume experiments were performed using 9%, 15%, and 21% sediment mixture concentrations composed of sand, silt, clay, and tap water, on varying bed slopes of 6 degrees, 8 degrees, and 9.5 degrees, and with discharge rates of 10 and 15m(3)/hr. In addition to the characteristics of the boundary and plug layers, which have been previously used for the classification of open-channel clay-laden flows, the newly presented classification also incorporates the treatment of the free shear layer. The flow states within the boundary and free shear layers were established using calculation of the inner variable, self-similarity considerations, and the magnitude of the apparent viscosity. Based on the experimental observations four flow types were recognized: (1) a clay-rich plug flow with a laminar free shear layer, a plug layer, and a laminar boundary layer, (2) a top transitional plug flow containing a turbulent free shear layer, a plug layer, and a laminar boundary layer, (3) a transitional turbidity current with a turbulent free shear layer, no plug layer, and a laminar boundary layer, and (4) a fully turbulent turbidity current. A connection between the emplaced deposits and the relevant flow types is drawn and it is shown that a Froude number, two Reynolds numbers, and a dimensionless yield stress parameter are sufficient to associate an experimental flow type with a natural large-scale density flow. Plain Language Summary Deposits of submarine density flows can be important hydrocarbon reservoirs. Quality of these reservoirs is primarily controlled by grain size and clay concentration of the sediment mixture at the time of deposition. These parameters are dictated by the structures of the sediment carrying flow at the time of deposition. This study proposes a classification for muddy subaqueous density flows based on the flow structures. According to this classif

This study presents a classification for subaqueous clay-laden sediment gravity flows. A series of laboratory flume experiments were performed using 9%, 15%, and 21% sediment mixture concentrations composed of sand, silt, clay, and tap water, on varying bed slopes of 6 degrees, 8 degrees, and 9.5 degrees, and with discharge rates of 10 and 15m(3)/hr. In addition to the characteristics of the boundary and plug layers, which have been previously used for the classification of open-channel clay-laden flows, the newly presented classification also incorporates the treatment of the free shear layer. The flow states within the boundary and free shear layers were established using calculation of the inner variable, self-similarity considerations, and the magnitude of the apparent viscosity. Based on the experimental observations four flow types were recognized: (1) a clay-rich plug flow with a laminar free shear layer, a plug layer, and a laminar boundary layer, (2) a top transitional plug flow containing a turbulent free shear layer, a plug layer, and a laminar boundary layer, (3) a transitional turbidity current with a turbulent free shear layer, no plug layer, and a laminar boundary layer, and (4) a fully turbulent turbidity current. A connection between the emplaced deposits and the relevant flow types is drawn and it is shown that a Froude number, two Reynolds numbers, and a dimensionless yield stress parameter are sufficient to associate an experimental flow type with a natural large-scale density flow. Plain Language Summary Deposits of submarine density flows can be important hydrocarbon reservoirs. Quality of these reservoirs is primarily controlled by grain size and clay concentration of the sediment mixture at the time of deposition. These parameters are dictated by the structures of the sediment carrying flow at the time of deposition. This study proposes a classification for muddy subaqueous density flows based on the flow structures. According to this classif

This study presents a classification for subaqueous clay-laden sediment gravity flows. A series of laboratory flume experiments were performed using 9%, 15%, and 21% sediment mixture concentrations composed of sand, silt, clay, and tap water, on varying bed slopes of 6 degrees, 8 degrees, and 9.5 degrees, and with discharge rates of 10 and 15m(3)/hr. In addition to the characteristics of the boundary and plug layers, which have been previously used for the classification of open-channel clay-laden flows, the newly presented classification also incorporates the treatment of the free shear layer. The flow states within the boundary and free shear layers were established using calculation of the inner variable, self-similarity considerations, and the magnitude of the apparent viscosity. Based on the experimental observations four flow types were recognized: (1) a clay-rich plug flow with a laminar free shear layer, a plug layer, and a laminar boundary layer, (2) a top transitional plug flow containing a turbulent free shear layer, a plug layer, and a laminar boundary layer, (3) a transitional turbidity current with a turbulent free shear layer, no plug layer, and a laminar boundary layer, and (4) a fully turbulent turbidity current. A connection between the emplaced deposits and the relevant flow types is drawn and it is shown that a Froude number, two Reynolds numbers, and a dimensionless yield stress parameter are sufficient to associate an experimental flow type with a natural large-scale density flow. Plain Language Summary Deposits of submarine density flows can be important hydrocarbon reservoirs. Quality of these reservoirs is primarily controlled by grain size and clay concentration of the sediment mixture at the time of deposition. These parameters are dictated by the structures of the sediment carrying flow at the time of deposition. This study proposes a classification for muddy subaqueous density flows based on the flow structures. According to this classif

The sea floor of intraslope minibasins on passive continental margins plays a significant role in controlling turbidity current pathways and the resulting sediment distribution. To address this, laboratory analogue modelling of intraslope minibasin formation is combined with numerical flow simulations of multi-event turbidity currents. This approach permits an improved understanding of evolving flow–bathymetry–deposit interactions and the resulting internal stacking patterns of the infills of such minibasins. The bathymetry includes a shelf to slope channel followed by an upper minibasin, which are separated by a confining ridge from two lower minibasins that compares well with analogous bathymetries reported from natural settings. From a wider range of numerical flow experiments, a series of 100 consecutive flows is reported in detail. The turbidity currents are released into the channel and upon reaching the upper minibasin follow a series of stages from short initial ponding, ‘filling and spilling’ and an extended transition to long retrogradational ponding. Upon reaching the upper minibasin floor, the currents undergo a hydraulic jump and therefore much sediment is deposited in the central part of the minibasin and the counterslope. This modifies the bathymetry such that in the fill and spill stage, flow stripping and grain-size partitioning cause some finer sediment to be transported across the confining ridge into the lower minibasins. Throughout the basin infill process, the sequences retrograde upstream, accompanied by lateral switching into locally formed depressions in the upper minibasin. After the fill and spill stage, significant deposition occurs in the channel where retrograding cyclic steps with wavelengths of 1 to 2 km develop as a function of pulsating flow criticality. These results are at variance with conventional schemes that emphasize sequential downstream minibasin filling through ponding dominated by vertical aggradation. Comparison of these

ICDP workshop COring the NOrth Sea Cenozoic focused on the scientific objectives and the technical aspects of drilling and sampling. Some 55 participants attended the meeting, ranging from climate scientists, drilling engineers, and geophysicists to stratigraphers and public outreach experts. Discussion on the proposed research sharpened the main research lines and led to working groups and the necessary technical details to compile a full proposal that was submitted in January 2016.