Abstract:Bypassing turbidity currents travel downslope while depositing only a minor part of their suspended sediment load. Along the way, they may encounter a slope break (i.e. an abrupt decrease in slope angle) that initiates the deposition of sediment. Depending on their proximal initiation point, these turbiditic deposits in slope-break systems can form potential reservoirs for hydrocarbons. The present experimental study establishes the resulting turbidite deposits as a function of the geometry in a slope-break sy… Show more
“…It is, therefore, common practice in geoscience to use scaled (“analog”) laboratory experiments with materials and geometries analogous to the geological materials and processes ( Kavanagh et al., 2018 ). Sedimentologists often study deposition and erosion processes in a laboratory flume (e.g., Baar et al., 2018 ; Pohl et al., 2020 ). Volcanologists use analog experiments to study all the various components of the magmatic system, from the magma reservoir ( Galland et al., 2014 ) and plumbing system ( Taisne et al., 2011 ) to eruptions and their products ( Del Bello et al., 2017 ; Iverson et al., 2010 ; Lev et al., 2019 ; Lube et al., 2015 ).…”
Section: Current Measurement Techniques Used To Study Geological Flowmentioning
confidence: 99%
“…Although useful, such tools provide only a local measurement at a specific point and not a full picture of the entire flow. Figure 1 Examples of Analog Experiments Simulating Geological Multiphase Flows, Showing Experimental Setups and Resulting Images and Measurements (A) Experimental setup of a flume experiment ( Pohl et al., 2020 ), where a mixture of sediments and fresh water is released into a water tank. Velocity is measured using an ultrasonic velocity probe (UVP) positioned above the flow.…”
Section: Current Measurement Techniques Used To Study Geological Flowmentioning
confidence: 99%
“… (A) Experimental setup of a flume experiment ( Pohl et al., 2020 ), where a mixture of sediments and fresh water is released into a water tank. Velocity is measured using an ultrasonic velocity probe (UVP) positioned above the flow.…”
Section: Current Measurement Techniques Used To Study Geological Flowmentioning
Summary
Geological flows—from mudslides to volcanic eruptions—are often opaque and consist of multiple interacting phases. Scaled laboratory geological experiments using analog materials have often been limited to optical imaging of flow exteriors or
ex situ
measurements. Geological flows often include internal phase transitions and chemical reactions that are difficult to image externally. Thus, many physical mechanisms underlying geological flows remain unknown, hindering model development. We propose using magnetic resonance imaging (MRI) to enhance geosciences via non-invasive,
in situ
measurements of 3D flows. MRI is currently used to characterize the interior dynamics of multiphase flows, distinguishing between different chemical species as well as gas, liquid, and solid phases, while quantitatively measuring concentration, velocity, and diffusion fields. This perspective describes the potential of MRI techniques to image dynamics within scaled geological flow experiments and the potential of technique development for geological samples to be transferred to other disciplines utilizing MRI.
“…It is, therefore, common practice in geoscience to use scaled (“analog”) laboratory experiments with materials and geometries analogous to the geological materials and processes ( Kavanagh et al., 2018 ). Sedimentologists often study deposition and erosion processes in a laboratory flume (e.g., Baar et al., 2018 ; Pohl et al., 2020 ). Volcanologists use analog experiments to study all the various components of the magmatic system, from the magma reservoir ( Galland et al., 2014 ) and plumbing system ( Taisne et al., 2011 ) to eruptions and their products ( Del Bello et al., 2017 ; Iverson et al., 2010 ; Lev et al., 2019 ; Lube et al., 2015 ).…”
Section: Current Measurement Techniques Used To Study Geological Flowmentioning
confidence: 99%
“…Although useful, such tools provide only a local measurement at a specific point and not a full picture of the entire flow. Figure 1 Examples of Analog Experiments Simulating Geological Multiphase Flows, Showing Experimental Setups and Resulting Images and Measurements (A) Experimental setup of a flume experiment ( Pohl et al., 2020 ), where a mixture of sediments and fresh water is released into a water tank. Velocity is measured using an ultrasonic velocity probe (UVP) positioned above the flow.…”
Section: Current Measurement Techniques Used To Study Geological Flowmentioning
confidence: 99%
“… (A) Experimental setup of a flume experiment ( Pohl et al., 2020 ), where a mixture of sediments and fresh water is released into a water tank. Velocity is measured using an ultrasonic velocity probe (UVP) positioned above the flow.…”
Section: Current Measurement Techniques Used To Study Geological Flowmentioning
Summary
Geological flows—from mudslides to volcanic eruptions—are often opaque and consist of multiple interacting phases. Scaled laboratory geological experiments using analog materials have often been limited to optical imaging of flow exteriors or
ex situ
measurements. Geological flows often include internal phase transitions and chemical reactions that are difficult to image externally. Thus, many physical mechanisms underlying geological flows remain unknown, hindering model development. We propose using magnetic resonance imaging (MRI) to enhance geosciences via non-invasive,
in situ
measurements of 3D flows. MRI is currently used to characterize the interior dynamics of multiphase flows, distinguishing between different chemical species as well as gas, liquid, and solid phases, while quantitatively measuring concentration, velocity, and diffusion fields. This perspective describes the potential of MRI techniques to image dynamics within scaled geological flow experiments and the potential of technique development for geological samples to be transferred to other disciplines utilizing MRI.
“…Experimental turbidity currents reported by Eggenhuisen et al (2019) in the same flume showed that the same sediment as used in these experiments was bypassed by turbidity currents with a maximum velocity of 1.2 m/s with a slope flume floor of 8°. Pohl et al (2020) evidenced that flows were still bypassing with a slope of 6° slope. This is twice as fast as the maximum velocities measured in the beginning of the experiments in this study.…”
Section: Breach Stabilitymentioning
confidence: 97%
“…Specifically, here the relation between breaching failure evolution, the velocity of the generated turbidity current, and the occurrence of deposition and erosion in front of the failure was analysed. The slope of the floor in front of the failure was varied because this slope is commonly considered a primary control on turbidity current characteristics (Kneller, 2003;Stevenson et al, 2015;Pohl et al, 2020). Flow thickness, volumetric discharge, and rate of deposition were analysed in order to answer the question: How does the strength of the turbidity current relate to an evolving breaching failure?…”
The influence of underwater embankment properties on breaching failures De invloed van de opbouw van onderwatertaluds op taludvervloeiing (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. H.R.B.M. Kummeling, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 28 augustus 2020 des middags te 4.
Deep‐water depositional systems are the ultimate sink for vast quantities of terrigenous sediment, organic carbon and anthropogenic pollutants, forming valuable archives of environmental change. Our understanding of the distribution of these particles and the preservation of environmental signals, in deep‐water systems is limited due to the inaccessibility of modern systems, and the incomplete nature of ancient systems. Here, the deposit of a physically modelled turbidity current was sampled (n = 49) to determine how grain size and grain type vary spatially. The turbidity current had a sediment concentration of 17%. The sediment consisted of, by weight, 65% quartz sand (2.65 g/cm3), 17.5% silt (2.65 g/cm3), 7.5% clay (2.60 g/cm3) and 5% each of sand‐grade garnet (3.90 g/cm3) and microplastic fragments (1.50 g/cm3). The grain size and composition of each sample was determined using laser diffraction and density separation, respectively. The results show that: (a) bulk grain size coarsened axially downstream on the basin floor challenging the notion that basin floor deposits fine radially from an apex upon becoming unconfined; (b) no sample composition matched the input composition of the flow, indicating that allogenic signals can be autogenically shredded and spatially variable in sediment gravity flow deposits; and (c) microplastic fragments were concentrated in levee and lateral basin floor fringe positions; however, microplastic concentrations in these positions were lower than input, suggesting microplastics bypassed the sampled positions. These findings have implications for: (a) the development of ‘finger‐like’ geometries and facies distributions observed in modern and ancient systems; (b) interpreting environmental signals in the stratigraphic record; and (c) predicting the distribution of microplastics on the sea floor.
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