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Sediment concentration profiles of the turbidity currents E1 and E2 at the mooring site S2 a Profiles of the inverted SSC for E1. The area under the black dashed line was affected by the side lobe interference. The yellow line indicates the local tidal oscillation (positive value is ebb phase). b Plots of the inverted SSC at 7, 12, 22, 42 and 62 MAB for E1, and the calculated SSC from RBR-TU at 72 MAB and RCM-TU at 12 MAB. Different colors represent the SSC in different heights those are indicated by white dashed lines in (a). c Inverted SSC profiles for E1. d Plots of the inverted SSC at 7, 12, 22, 42 and 62 MAB for E2, and the calculated SSC from RBR-TU at 72 MAB. Different colors represent the SSC in different heights those are indicated by white dashed lines in (c). Only the SSC after E1 and E2 happening was shown.
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Sediment gravity flows are the most direct and efficient transport mechanisms for moving terrestrial sediments into deep oceans. Scarcity of firsthand measurements, however, has hindered the quantitative, even qualitative characterization of such flows. Here we present a unique year-long data record from ~4000 m depth in the Manila Trench that capt...
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... In contrast, the intervals S1, T1, and S2 within the UU show an increase in fine sand content and are poorly sorted, markedly different from the overlying clayey intervals, and they lack typical hyperpycnal flow features like plant fragments (Fig. 10). These characteristics suggest the presence of turbidites that evolved from slumps on a subaqueous delta (Sparkes et al., 2015;Liu et al., 2023). Furthermore, failure/collapse/resuspension-related turbidity flows can compact underlying sediments, forming denser layers with increasing bulk density ( Fig. 10; Hubble et al., 2019;Mollison et al., 2020), as evidenced by an increase in bulk density above the erosional surface in core YRD2 ( Fig. 10; from ∼1.30 g/cc to ∼1.36 g/cc). ...
Downslope sediment gravity flows (SGFs) and longitudinal (along-slope) transport regimes play critical roles in shaping subaqueous clinoforms globally, yet their combined impacts on sedimentation in subaqueous deltas, particularly in shallow marine subaqueous deltas, remain less understood compared to those on lower continental slopes. Here, we address this gap by examining the sedimentary and morphological patterns of SGF accumulations at the toe of the modern Huanghe subaqueous delta, using dense, high-resolution seismic data and sediment cores, along with historical bathymetric data. Building on prior research that identified a widespread SGF wedge superimposed on a conventional Gilbert-type clinoform, our seismic data confirm that this wedge exhibits shore-parallel elongated geometry that thickens from northwest to southeast, and aligns with the prevailing southeastward, tidal-driven contour currents. Near the abandoned Diaokou Lobe (upcurrent area), the wedge experiences significant erosion, as evidenced by truncation at its top, which is attributed to postdepositional erosion by contour currents. Downdrift, the wedge transitions from extensive erosion near the Diaokou Lobe to accumulation toward the active Qingshuigou Lobe, which involves the reworking and redistribution of eroded sediments from upcurrent locations to downcurrent areas through longitudinal transport regimes. Sediment cores that fully or partially penetrate the SGF wedge reveal intervals characterized by accumulations reworked by tidal or residual currents (e.g., sand-mud interbedding and/or bioturbation), interspersed with SGF-dominated layers. These findings highlight the important role of interactions between SGFs and contour currents in shaping the subaqueous deltas of both active and abandoned lobes. Variability in the intensity of contour currents and lobe switching events led to two distinct interaction patterns: (1) SGF-dominated sediments reworked by longitudinal transport, which is the predominant interaction pattern, and (2) slower SGF fine-grained plumes directly driven by longitudinal transport. These patterns share similarities with deep-water accumulations shaped by the interplay of SGFs and contour currents in terms of morphology and sedimentary features. These insights could have broader implications for predicting sedimentary and geomorphological evolution in other river deltas experiencing similar long-term SGF and longitudinal transport interactions.
... The second type was much slower (≤0.0.5 ms 1 ) and it is suggested that it had minimal impact on the seabed. These different types of turbidity currents are similar to previously measured ones elsewhere in submarine canyons (Khripounoff et al., 2012;Liu et al., 2023;Normandeau et al., 2020) and have different effects on the sedimentology of the preserved deposits. The faster turbidity currents with a dense head are responsible for the migration of the crescentic bedforms and deposit massive sand on the cyclic steps and on the fjord bottom. ...
Sediment transported to fjords is redistributed by turbidity currents and sometimes fails on steep sidewall slopes, forming marine geohazards that are known to impact infrastructure. Since marine geohazards are poorly understood in Arctic Fjords due to lack of data and monitoring, a comprehensive study of Southwind Fjord, Baffin Island, was undertaken to assess the modern processes leading to marine geohazards and their products on the seabed. Repeat measurements of bathymetric changes and flow measurements from moorings revealed that turbidity currents with measured speeds up to 1.75 ms⁻¹ lead to the migration of cyclic steps in the submarine channel of the prodelta. Fast and dense heads of turbidity currents transport sand kilometers away from the channel‐mouth during larger events and remain confined in the prodelta channel and on the fjord basin floor. Clayey silts are deposited on the sidewalls of the fjord as a result of both overflowing turbidity currents and settling of meltwater plumes. Since sand is confined to the fjord bottom, there is no regional weak layer on the sidewall that is responsible for the large number of submarine landslides observed on the slopes. Low factor of safety of sidewall sediment (1.7 at 2.5 m depth) indicates that limited environmental loading of the sediment can trigger shallow (≤3 m) failures. This is confirmed by repeat bathymetric and core data showing asynchronous failures caused by icebergs and subaerial debris flows. This study provides a comprehensive overview of modern seabed processes and provides new perspectives on the wide variability of causes of marine geohazards in glacierized fjords that will be useful to interpret other similar environments with limited seafloor data.
... However, in the northern SCS, a few studies monitored turbidity currents. For example, Liu et al. recorded two types of turbidity currents that occurred in the Manila Trench, northeastern SCS: slow (~0.4 m/s), long-duration and low-concentration flow, and fast (1.5 m/s), short-lived, and higher-concentration flow [55]. Zhang et al. observed typhoon-triggered frequent turbidity currents in the Gaoping submarine canyon off southwestern Taiwan and measured a velocity of 0.15 m/s at the upper part of the flow on the levee [56]. ...
Seismic data reveal that the shelf edge of the Pearl River Mouth Basin in the northern South China Sea is characterized by slope channels that have consistently migrated in a north-easterly direction over millions of years. Previous research suggests that the channel migration is driven by the interplay between along-slope bottom currents and downslope turbidity currents. Here, we propose an alternative interpretation, suggesting the migrating channels are actually a series of channel–levee systems and the migration is driven by their own evolution of erosion–deposition under the influence of the Coriolis force. A detailed interpretation of high-resolution seismic data reveals seven types of architectural elements, characteristic of channel–levee systems, which are erosional bases, outer levees, inner levees, channel-axis fills, marginal slumps, drapes, and lobes. An analysis of the sequence stratigraphy and stacking pattern of channels suggests that channel migration from the middle Miocene to the present is discontinuous with at least three regional discontinuities within the channel migration sequence marked by regional drapes. Down-dipping reflections along the margin of channels, previously interpreted as bottom-currents deposits, are here reinterpreted as mass-transport processes along steep channel walls. The migration is most prominent in the middle reach, where erosion and deposition coexist and dominate alternately in two different phases. During the long-term canyon-filling turbidity currents prevailing phase, deposition dominates, leading to the development of a prominent asymmetric right-hand (west) inner levee due to the Coriolis force. In contrast, during the canyon-flushing turbidity currents prevailing phase, erosion dominates and the preferred right-hand (west) inner levee enforces the flow to erode eastward, then drives the channel migrating eastward. The alternating effects of erosion and deposition ultimately result in unidirectional channel migration.
... Submarine gravity flows, such as debris flow, mudflow, and turbidity currents, are seafloor density-driven flows that transport large amount of submarine sediment under the influence of gravity. These highdensity currents, frequently resulting from submarine landslides, are widespread globally on various submarine slopes and significantly transport sediments from the continental shelf to the deep ocean floor (Brizuela et al., 2019;Halsey et al., 2017;Heerema et al., 2020;Kneller et al., 2016;Liu et al., 2023a;Shan et al., 2022;Talling, 2013;Wells and Dorrell, 2021). The global distribution of submarine landslide is presented in Fig. 1 below. ...
... Specifically, the impact of submarine gravity flows on offshore pipelines is a significant concern that affects the safe functioning of pipelines (Locat and Lee, 2002) and is presently a much-discussed subject (Boukpeti et al., 2012;Guo et al., 2023aGuo et al., , 2023bLiu et al., 2015). Field observations have documented the occurrence of powerful turbidity currents in the ocean (Hughes Clarke, 2016;Khripounoff et al., 2003;Liu et al., 2023a;Paull et al., 2018;Sequeiros et al., 2019;Talling et al., 2013Talling et al., , 2022, while other studies have employed physical and numerical models to describe detailed evolution, structure, and dynamic characteristics of these gravity currents (Goodarzi et al., 2020;He et al., 2017He et al., , 2018He et al., , 2019He et al., , 2022Okon et al., 2021;Taki and Parker, 2005;Zhu et al., 2022). Although some research articles have provided a detailed review of submarine gravity flows, including their flow dynamics and resulting deposits (Meiburg et al., 2015;Meiburg and Kneller, 2010;Talling et al., 2023), a comprehensive review of recent research advances involving submarine gravity flows interaction with offshore pipelines is necessary to complement the review of Fan et al. (2023). ...
... Engineering Geology 347 (2025) 107914 Fig. 3), as widely documented since the 1950s (Gorsline et al., 2000;Heezen and Ewing, 1952). They commonly occur on both passive and active continental margins, particularly in locations with rugged terrain and complex geological formations (Felix, 2002;Liu et al., 2023a;Meiburg and Kneller, 2010;Paull et al., 2018;Sequeiros et al., 2019). Given that turbidity currents transport suspended particles due to fluid turbulence, understanding the trigger mechanisms of these sedimentdriven currents is important. ...
The increase in offshore exploration for oil and natural gas has raised concerns about the safety of pipelines in the face of submarine slides, debris flow, and high-density turbidity currents. These submarine gravity flows constitute significant marine geohazards as they undermine the structural integrity of offshore pipelines, underscoring the importance of understanding the complexities of the dynamic interaction process. We herein present a comprehensive review of the complex interactions between submarine gravity flows and offshore pipelines. Emphasis is on the influence of pipeline characteristics, environmental factors, and flow properties on the impact force exerted on the offshore pipeline and the overall interaction process. Recent literature indicates that implementing modified pipeline designs, such as streamlined shapes and advanced design materials, can effectively minimize drag and lift forces, thus potentially reducing the risk of damage by submarine gravity flows. This underscores the need to combine sophisticated engineering designs and durable materials to protect offshore pipelines. This paper provides an in-depth understanding of the interaction between submarine gravity flows and pipeline infrastructures, suggesting the implementation of real-time monitoring technologies, novel pipeline materials, and the adoption of innovative designs that can withstand adverse seafloor environments and effectively mitigate the risk of sediment-induced damage in landslide-prone regions. The article summarizes existing knowledge on mitigative technologies and recommends areas for further investigation to improve the safety and durability of submarine pipelines.
... Particle-driven gravity currents have a notable impact on various geological and oceanic processes, including erosion processes, the formation of submarine canyons, and the transportation of sediment to the abyssal plains (Kneller & Buckee, 2000). Sediment deposits resulting from particle-driven gravity currents have been documented both in the presentday ocean floor and in geological records (Liu et al., 2023;Paull et al., 2018;Simpson, 1997). ...
This chapter presents important experimental and numerical findings regarding the dynamics of gravity currents in various stratified environments. First, the macro- and microstructure of gravity currents descending an inclined bed in linearly stratified environments were studied using high-speed camcorders and particle image velocimetry technology. Results indicate that the dynamics of gravity current are complicated by ambient stratification. Two equations with three fitted parameters from experimental data were proposed to predict the velocity profiles of gravity current. Secondly, gravity currents released from two-layer stratified locks were also experimentally studied, with emphasis on the effect of the initial height ratio and lock aspect ratio on the mixing process. Analysis reveals the importance of initial height ratio and lock aspect ratio in determining the front velocity and mixing process within the gravity current. Finally, the dynamics of turbidity currents in linearly stratified environments were numerically simulated with the aim of elucidating the effects of ambient stratification, bed slope, and particle settling velocity on the evolution process of the currents. The study demonstrates that if the relative stratification parameter is greater than unity (i.e., Sr>1), the head of the current would separate from the slope and intrude into the environment at the level of neutral buoyancy. Strong ambient stratification reduces the rate at which potential energy is converted to kinetic energy, while a higher particle settling velocity accelerates the rate at which kinetic energy is dissipated. We conclude that the velocity and fluid structure of gravity currents can be complicated by ambient stratification and present a theoretical model that accurately predicts the separation depth of turbidity currents in density-stratified environments.
... Since greater δ were found in experiments with smaller mean diameter (d 50 ) particles, the turbidity currents with a higher proportion of fine particles should be able to transport MPs over longer distances, i. e., they are deposited farther away from their source. This hypothesis is supported by field studies, which have found that silty turbidity currents in the Manila Trench travel longer distances in ocean waters compared to fast-moving sandy turbidity currents (Liu et al., 2023). Therefore, the grain size composition of turbidity currents influences not only the deposition of natural sediment (Culp et al., 2021;Gladstone and Sparks, 1998;Harris et al., 2002;Soler et al., 2020;Zhou et al., 2022), but also the depositional sequence associated to MP particles. ...
... The SCs with acoustically chaotic fill are less prevalent in seismic profiles, which are more frequently located near the middle part of the delta front. Collapses can trigger turbidity flows that rapidly accumulate various sediments, more likely forming chaotic reflection fills (Liu et al., 2023) (Figure 5). Rapid sediment deposition also prevents effective pore water expulsion, leaving the sediments weak and under-consolidated (Gao, 2011), destabilizing the strata, and significantly contributing to various submarine geological disasters. ...
Background
Gravity-driven depositional processes play a pivotal role in shaping the geomorphology of subaqueous deltas worldwide, particularly by eroding the seafloor, leading to the formation of rugged submarine channels (SCs) and triggering various subaqueous geohazards. A comprehensive understanding of SCs is crucial for elucidating these depositional mechanisms and mitigating the risks associated with submarine geohazards. Although SCs in the Huanghe delta front have been previously identified, often described as seafloor gullies or subsurface “disturbed strata,” most studies have primarily concentrated on their engineering geological properties. However, there has been limited research on the scale, morphology, and development of these SCs, especially those that are buried within the stratigraphy.
Methods
This study integrates high-resolution sub-bottom data, sediment core analyses, and historical bathymetric data to investigate the morphology, distribution, and formation mechanisms of SCs in the Huanghe subaqueous delta.
Results
The SCs, both buried and exposed, are widespread along the middle and upper delta front, predominantly located at or near the landward flank of sediment gravity flow (SGF) -related accumulations. The buried SCs are characterized by cut-and-fill structures with transparent to semi-transparent fills, indicating rapid infilling processes as SGF energy dissipates. These buried channels were preserved within different sets of delta front deposits formed during 1855–1964 CE, 1964–1976 CE, and 1976–2007 CE, with the latter two periods separated by a significant lobe-switching event in 1976 CE. This event, combined with prevailing southeastward sediment transport and erosional regimes, appears to have controlled the preservation of SCs along the delta front: SCs in the Diaokou Lobe's delta front (pre-1976) suffered significant erosion, leaving only one set of channel (erosional remnants) preserved, while the SCs in the Qingshuigou Lobe's delta front (post-1976) are characterized by well-preserved, multi-phase channels at different horizons. The cross-section morphology of the SCs reveal three primary types: symmetrical, asymmetrical, and composite, corresponding respectively to (1) idealized SGF incision, (2) uneven incision intensity on either side of the SCs, and (3) the merging of two or more symmetrical/asymmetrical SCs.
Conclusions
We describe in detail the morphology, distribution and development of SCs in the modern Huanghe subaqueous delta. These findings provide insights into the formation and distribution of SCs in other shallow marine settings, particularly in delta front areas, and potentially offer information for disaster prevention and engineering development in such regions.
... One Petrel-4 000glider was deployed on 14 September 2019 in northeastern SCS (Fig. 1). Its primary goal was to measure temperature and salinity profiles along the upper reach of the Manila Trench coordinated by a different research project (Liu et al., 2023). In 41 d until recovery on October 25, 2019, a total of 35 valid temperature and salinity profiles (from September 28 to October 12), sampled at 1 Hz, were recorded (Figs 1a and b). ...
Typhoons in the western Pacific have a significant impact on the transport of heat, salt and particles through the Luzon Strait. However, there are very limited field observations of this impact because of extreme difficulties and even dangers for ship-based measurements during the rough weather. Here, we present the preliminary results from analyzing a dataset collected by a glider deployed west of the Luzon Strait a few days prior to the arrival of typhoon MITAG. The gilder data revealed an abnormally salinity (>34.8) subsurface water apparently sourced from Kuroshio intrusion during the typhoon. When typhoon MITAG traveled on the east of the Luzon Strait, the positive wind stress curl strengthened the cyclonic eddy and weakened the anti-cyclonic eddy. This led to a slowdown of Kuroshio and made its intrusion easier. The main axis of the Kuroshio at the northern part of the strait shifted westward after the typhoon and did not return to its original position until a week later. The Ekman transport from persistent northerly wind of typhoon MITAG was significant, but its importance in enhancing the Kuroshio intrusion is only secondary relative to the eddies variations.
... This ensures that any simulated deposition patterns are solely influenced by the longitudinal profiles extracted from the observed topography. Considering the duration of observed turbidity currents events ranging from several hours to several days (Azpiroz-Zabala et al., 2017;Simmons et al., 2020;Pope et al., 2022a;Liu et al., 2023), the simulation time for each run was set at 20,000 s to ensure that the simulated flow can generally reach the end of the profile in each simulation. Time-series of the Froude number (Fr) and Shields stress (τ * ), two dimensionless parameters used for describing the hydrodynamic evolution of modelled flows (Shields, 1936;Wei et al., 2014;Vellinga et al., 2018;Ge et al., 2022), were calculated. ...
... The decreasing pattern of TLP with distance from shore follows the attenuation functions FuncI and FuncII. If the bottom water depth of the water column reaches ∼2,000 m before TLP is transported to a distance of 400 km or 800 km, then thereafter, TLP will always be transported to seaward adjacent water columns at a depth of ∼2,000 m according to the attenuation function as suggested by previous observations (Liu et al., 2023;Paull et al., 2018). Detailed descriptions of these forcing fields are listed in Table 1. ...
Lithogenic materials such as terrigenous lithogenic particles (TLP) can efficiently promote the formation and sinking of mineral‐associated marine organic matter, acting as important ballast and potentially playing an important role in the global carbon cycle. To assess the influence of TLP on fluxes of particulate organic carbon (POC) and other biogeochemical cycles, we construct TLP forcing fields based on global riverine suspended sediment data and then apply them to the Community Earth System Model, version 2 (CESM2) modified with the TLP ballasting effect term. Simulations forced by different concentrations of TLP transported in the surface ocean or along the bottom of continental shelves and slopes are conducted. When the TLP transports seaward along the bottom, simulated POC fluxes at 100 and 2,000 m decrease about 11% and 19%, respectively, for the global ocean, and about 9% and 12%, respectively, for the oceanic regions of continental margins. The initial abiotic ballast processes triggered by TLP input increase POC fluxes, causing additional removal and burial of dissolved iron in continental margins. This further enhances the accumulation of macronutrients in the upwelling regions and their advection transport to neighboring subtropical gyres, thus altering regional productivity when simulations reach quasi‐equilibrium. When consider the impacts of TLP in simulations, the simulated POC flux exhibits an increase in subtropical gyres but a decrease in tropical Pacific and mid‐high latitude regions. The present work highlights the importance of TLP in global biogeochemical cycles, suggesting that the amount of carbon sequestration might be overestimated without TLP in models.
