Initiation Processes and Flow Evolution of Turbidity CurrentsImplications for the Depositional Record

1991 ◽  
Author(s):  
William R. Normark ◽  
David J. W. Piper
Keyword(s):  
Turbidity Currents ◽  
Flow Evolution

scholarly journals Dynamics and deposition of sediment-bearing multi-pulsed flows and geological implication

2019 ◽  
Vol 89 (11) ◽  
pp. 1127-1139 ◽  
Author(s):  
Viet Luan Ho ◽  
Robert M. Dorrell ◽  
Gareth M. Keevil ◽  
Robert E. Thomas ◽  
Alan D. Burns ◽  
...  
Keyword(s):  
Internal Flow ◽  
Turbidity Currents ◽  
Pulsed Flows ◽  
Longitudinal Variations ◽  
Flow Evolution ◽  
Structure Of Deposits ◽  
Downstream Flow ◽  
Deposit Structure ◽  
Natural Scale ◽  
Geological Implication

ABSTRACT Previous studies on dilute, multi-pulsed, subaqueous saline flows have demonstrated that pulses will inevitably advect forwards to merge with the flow front. On the assumption that pulse merging occurs in natural-scale turbidity currents, it was suggested that multi-pulsed turbidites that display vertical cycles of coarsening and fining would transition laterally to single-pulsed, normally graded turbidites beyond the point of pulse merging. In this study, experiments of dilute, single- and multi-pulsed sediment-bearing flows (turbidity currents) are conducted to test the linkages between downstream flow evolution and associated deposit structure. Experimental data confirm that pulse merging occurs in laboratory-scale turbidity currents. However, only a weak correspondence was seen between longitudinal variations in the internal flow dynamics and the vertical structure of deposits; multi-pulsed deposits were documented, but transitioned to single-pulsed deposits before the pulse merging point. This early transition is attributed to rapid sedimentation-related depletion of the coarser-grained suspended fraction in the laboratory setting, whose absence may have prevented the distal development of multi-pulsed deposits; this factor complicates estimation of the transition point in natural-scale turbidite systems.

Particle-laden flow down a slope in uniform stratification

2014 ◽  
Vol 755 ◽  
pp. 251-273 ◽  
Author(s):  
Kate Snow ◽  
B. R. Sutherland
Keyword(s):  
Laboratory Experiments ◽  
Turbidity Current ◽  
Flow Speed ◽  
Turbidity Currents ◽  
Constant Density ◽  
Particle Settling ◽  
Flow Evolution ◽  
Explicit Formulae ◽  
Lock In ◽  
Particle Laden Flow

AbstractLock–release laboratory experiments are performed to examine saline and particle-laden flows down a slope into both constant-density and linearly stratified ambients. Both hypopycnal (surface-propagating) currents and hyperpycnal (turbidity) currents are examined, with the focus being upon the influence of ambient stratification on turbidity currents. Measurements are made of the along-slope front speed and the depth at which the turbidity current separates from the slope and intrudes into the ambient. These results are compared to the predictions of a theory that characterizes the flow evolution and separation depth in terms of the slope $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}s$, the entrainment parameter $E$ (the ratio of entrainment to flow speed), the relative stratification parameter $S$ (the ratio of the ambient density difference to the relative current density) and a new parameter $\gamma $ defined to be the ratio of the particle settling to entrainment speed. The implicit prediction for the separation depth, $H_s$, is made explicit by considering limits of small and large separation depth. In the former case of a ‘weak’ turbidity current, entrainment and particle settling are unimportant and separation occurs where the density of the ambient fluid equals the density of the fluid in the lock. In the latter case of a ‘strong’ turbidity current, entrainment and particle settling crucially affect the separation depth. Consistent with theory, we find that the separation depth indeed depends on $\gamma $ if the particle size (and hence settling rate) is sufficiently large and if the current propagates many lock lengths before separating from the slope. A composite prediction that combines the explicit formulae for the separation depth for weak and strong turbidity currents agrees well with experimental measurements over a wide parameter range.

BED INSTABILITY GENERATED BY TURBIDITY CURRENTS

2018 ◽  
Vol 74 (4) ◽  
pp. I_1105-I_1110
Author(s):  
Sytharith PEN ◽  
Norihiro IZUMI ◽  
Sakura HAGISAWA
Keyword(s):  
Turbidity Currents

scholarly journals Design and Application of an In Situ Test Device for Rheological Characteristic Measurements of Liquefied Submarine Sediments

2021 ◽  
Vol 9 (6) ◽  
pp. 639
Author(s):  
Hong Zhang ◽  
Xiaolei Liu ◽  
Anduo Chen ◽  
Weijia Li ◽  
Yang Lu ◽  
...  
Keyword(s):  
Yellow River ◽  
Rheological Characteristic ◽  
Yellow River Delta ◽  
Turbidity Currents ◽  
Rheological Characteristics ◽  
Submarine Landslides ◽  
Test Device ◽  
Offshore Area ◽  
In Situ Test

Liquefied submarine sediments can easily lead to submarine landslides and turbidity currents, and cause serious damage to offshore engineering facilities. Understanding the rheological characteristics of liquefied sediments is critical for improving our knowledge of the prevention of submarine geo-hazards and the evolution of submarine topography. In this study, an in situ test device was developed to measure the rheological properties of liquefied sediments. The test principle is the shear column theory. The device was tested in the subaqueous Yellow River delta, and the test results indicated that liquefied sediments can be regarded as “non-Newtonian fluids with shear thinning characteristics”. Furthermore, a laboratory rheological test was conducted as a contrast experiment to qualitatively verify the accuracy of the in situ test data. Through the comparison of experiments, it was proved that the use of the in situ device in this paper is suitable and reliable for the measurement of the rheological characteristics of liquefied submarine sediments. Considering the fact that liquefaction may occur in deeper water (>5 m), a work pattern for the device in the offshore area is given. This novel device provides a new way to test the undrained shear strength of liquefied sediments in submarine engineering.

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