Event-driven sediment flux in Hueneme and Mugu submarine canyons, southern California

Xu, Jingping; Swarzenski, Peter W.; Noble, Marlene A.; Li, Anchun

doi:10.1016/j.margeo.2009.12.007

Cited by 78 publications

(70 citation statements)

References 43 publications

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“…It is likely that the combination between eastward storm-associated longshore drift, the narrowing of the continental shelf and the actual geometry of the coast (Figs. 3, 6, and 11) can favor canyons located very close to headlands in capturing currents and trapping sediment flows in their heads, which may promote downwelling processes and trigger sporadic downslope gravity flows (Xu et al, 2010). Similar processes have been largely documented in the western Mediterranean, for example in the Cap de Creus Canyon in the Gulf of Lion Ulses et al, 2008).…”

Section: Canyon Maintenance Processes Over the Last Glacial Cyclementioning

confidence: 75%

Submarine canyons of north-western Sicily (Southern Tyrrhenian Sea): Variability in morphology, sedimentary processes and evolution on a tectonically active margin

Iacono

Sulli

Agate

2014

Deep Sea Research Part II: Topical Studies in Oceanography

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a b s t r a c tSwath-bathymetry, mono-channel and multi-channel seismic reflection records acquired during the last two decades on the northern Sicilian margin have unveiled a dense network of submarine canyons within the depth range of 80-2100 m. The canyons display a relevant variability in their geometry, morphology and sedimentary processes. The margin shows a young, tectonically active shelf to slope setting, linking the Sicilian-Maghrebian Thrust Belt to the Tyrrhenian oceanic realm, developed during the Neogene-Quaternary time span. The aim of this study is to highlight the main governing factors that contributed to the evolution and differentiation of the northern Sicilian canyons, mainly focusing on the Gulf of Palermo and on the Gulf of Castellammare. Tectonic control is more evident in the canyons of the Gulf of Palermo, with submarine landslides retrograding on a steep slope and mainly controlling their evolution. Otherwise, canyons, tributaries and gullies mapped in the Gulf of Castellammare developed on a less steep substrate and display sinuous to meandering paths, with a relevant role of coastal/shelf sedimentary inputs and downslope turbidity processes in their formation. Results suggest that, despite the geographically close proximity of the two study areas, the different structural settings of the Castellammare and Palermo Basins are mainly responsible for canyon variability. Data indicate likely ongoing uplift and tilting movements along the Sicilian margin, influencing the development of the studied canyons, which have probably been more active during the Quaternary glacial maxima than they are in the present day.

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Section: Canyon Maintenance Processes Over the Last Glacial Cyclementioning

confidence: 75%

Submarine canyons of north-western Sicily (Southern Tyrrhenian Sea): Variability in morphology, sedimentary processes and evolution on a tectonically active margin

Iacono

Sulli

Agate

2014

Deep Sea Research Part II: Topical Studies in Oceanography

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“…They also do not run-out for very long distances and did not exit the lower canyon (Shepard et al, 1969;Piper, 1970). The events in La Jolla and Scripps Canyon may be broadly similar to the stormtriggered events in the upper part of the Monterey Canyon (Paull et al, 2003(Paull et al, , 2010a(Paull et al, , 2010bXu et al, 2004;Xu et al, 2013) and the Hueneme and Mugu Canyons (Xu, 2010;Xu et al, 2010). However, at least one of the events in Scripps Canyon resulted from a slump (with a volume of 0.0001 km 3 ) located in the side of the canyon near its head (Marshall, 1978).…”

Section: Scripps and La Jolla Canyons Offshore Californiamentioning

confidence: 99%

“…Penetration of the ADCP through tens of metres of the flow shows that sediment concentrations were ≪5 vol.% (Hurther et al, 2011). Xu et al, 2010 calculated that a depth averaged sediment volume concentration of 0.04 to 0.06% was needed to obtain the observed flow speeds and thicknesses, using a Chezy-type equation (Bowen et al, 1984) that is discussed in Section 7.2.2.2. The velocity profiles have a similar shape to those of supercritical laboratory flows (Sequeiros et al, 2010), when scaled by flow thickness and depth averaged speed.…”

Section: Monterey Canyon Offshore Californiamentioning

confidence: 99%

“…The bedforms that then develop have gradients of~15°on the down-slope facing scarp, which may favour continued up-slope-migrating retrogressive breaching. Xu et al (2010) and Xu (2010) reported vertical velocity profiles for events in 2007 and 2008 in Hueneme Canyon and Mugu Canyon that are located to the north of the Santa Monica Basin. These measurements were made in 188 m and 179 m water depth near the head of these canyons, where the sea floor gradient is 2°.…”

Section: Scripps and La Jolla Canyons Offshore Californiamentioning

confidence: 99%

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How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows

Talling

Paull

Piper

2013

Earth-Science Reviews

211

184

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Subaqueous sediment density flows are one of the volumetrically most important processes for moving sediment across our planet, and form the largest sediment accumulations on Earth (submarine fans). They are also arguably the most sparely monitored major sediment transport processes on our planet. Significant advances have been made in documenting their timing and triggers, especially within submarine canyons and delta-fronts, and freshwater lakes and reservoirs, but the sediment concentration of flows that run out beyond the continental slope has never been measured directly. This limited amount of monitoring data contrasts sharply with other major types of sediment flow, such as river systems, and ensure that understanding submarine sediment density flows remains a major challenge for Earth science. The available monitoring data define a series of flow types whose character and deposits differ significantly. Large (N 100 km 3 ) failures on the continental slope can generate fast-moving (up to 19 m/s) flows that reach the deep ocean, and deposit thick layers of sand across submarine fans. Even small volume (0.008 km 3 ) canyon head failures can sometimes generate channelised flows that travel at N 5 m/s for several hundred kilometres. A single event off SE Taiwan shows that river floods can generate powerful flows that reach the deep ocean, in this case triggered by failure of recently deposited sediment in the canyon head. Direct monitoring evidence of powerful oceanic flows produced by plunging hyperpycnal flood water is lacking, although this process has produced shorter and weaker oceanic flows. Numerous flows can occur each year on river-fed delta fronts, where they can generate up-slope migrating crescentic bedforms. These flows tend to occur during the flood season, but are not necessarily associated with individual flood discharge peaks, suggesting that they are often triggered by delta-front slope failures. Powerful flows occur several times each year in canyons fed by sand from the shelf, associated with strong wave action. These flows can also generate up-slope migrating crescentic bedforms that most likely originate due to retrogressive breaching associated with a dense near-bed layer of sediment. Expanded dilute flows that are supercritical and fully turbulent are also triggered by wave action in canyons. Sediment density flows in lakes and reservoirs generated by plunging river flood water have been monitored in much greater detail. They are typically very dilute (b 0.01 vol.% sediment) and travel at b 50 cm/s, and are prone to generating interflows within the density stratified freshwater. A key objective for future work is to develop measurement techniques for seeing through overlying dilute clouds of sediment, to determine whether dense near-bed layers are present. There is also a need to combine monitoring of flows with detailed analyses of flow deposits, in order to understand how flows are recorded in the rock record. Finally, a source-to-sink approach is needed because the character of subm...

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“…It is already the location of detailed and technologically sophisticated monitoring efforts (Paull et al 2010a), including the first velocity and density profiles through active flows ( Fig. 2; Xu et al 2004Xu et al , 2010Xu et al , 2013Xu et al , 2014Xu 2010). A major Monterey Bay Aquarium Research Institute (MBARI), US Geological Survey, and UK Natural Environment Research Council monitoring experiment is already funded from 2014-2017, which includes deployment of a seafloor observatory, event detectors along the flow path of the sandy floor of the canyon, and four sets of ADCP moorings at water depths of 300 m to 1850 m. An extensive set of cores (including vibracores taken with a remotely operated vehicle (ROV); Fig.…”

Section: Suggestions For Key Future Research Directionsmentioning

confidence: 99%

Key Future Directions For Research On Turbidity Currents and Their Deposits

Talling

Allin

Armitage

et al. 2015

Journal of Sedimentary Research

165

117

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Turbidity currents, and other types of submarine sediment density flow, redistribute more sediment across the surface of the Earth than any other sediment flow process, yet their sediment concentration has never been measured directly in the deep ocean. The deposits of these flows are of societal importance as imperfect records of past earthquakes and tsunamogenic landslides and as the reservoir rocks for many deep-water petroleum accumulations. Key future research directions on these flows and their deposits were identified at an informal workshop in September 2013. This contribution summarizes conclusions from that workshop, and engages the wider community in this debate. International efforts are needed for an initiative to monitor and understand a series of test sites where flows occur frequently, which needs coordination to optimize sharing of equipment and interpretation of data. Direct monitoring observations should be combined with cores and seismic data to link flow and deposit character, whilst experimental and numerical models play a key role in understanding field observations. Such an initiative may be timely and feasible, due to recent technological advances in monitoring sensors, moorings, and autonomous data recovery. This is illustrated here by recently collected data from the Squamish River delta, Monterey Canyon, Congo Canyon, and offshore SE Taiwan. A series of other key topics are then highlighted. Theoretical considerations suggest that supercritical flows may often occur on gradients of greater than , 0.6u. Trains of up-slope-migrating bedforms have recently been mapped in a wide range of marine and freshwater settings. They may result from repeated hydraulic jumps in supercritical flows, and dense (greater than approximately 10% volume) near-bed layers may need to be invoked to explain transport of heavy (25 to 1,000 kg) blocks. Future work needs to understand how sediment is transported in these bedforms, the internal structure and preservation potential of their deposits, and their use in facies prediction. Turbulence damping may be widespread and commonplace in submarine sediment density flows, particularly as flows decelerate, because it can occur at low (, 0.1%) volume concentrations. This could have important implications for flow evolution and deposit geometries. Better quantitative constraints are needed on what controls flow capacity and competence, together with improved constraints on bed erosion and sediment resuspension. Recent advances in understanding dilute or mainly saline flows in submarine channels should be extended to explore how flow behavior changes as sediment concentrations increase. The petroleum industry requires predictive models of longer-term channel system behavior and resulting deposit architecture, and for these purposes it is important to distinguish between geomorphic and stratigraphic surfaces

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Event-driven sediment flux in Hueneme and Mugu submarine canyons, southern California

Cited by 78 publications

References 43 publications

Submarine canyons of north-western Sicily (Southern Tyrrhenian Sea): Variability in morphology, sedimentary processes and evolution on a tectonically active margin

Submarine canyons of north-western Sicily (Southern Tyrrhenian Sea): Variability in morphology, sedimentary processes and evolution on a tectonically active margin

How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows

Key Future Directions For Research On Turbidity Currents and Their Deposits

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