Formation and transport of fluid mud triggered by typhoon events in front of the subaqueous Changjiang Delta

Tang, Jieping; Wu, Hao; Xing, Fei; Zhang, Fan; Tang, Bixuan; Li, Gaochong; Wang, Ya Ping

doi:10.1016/j.margeo.2023.107052

Cited by 7 publications

(2 citation statements)

References 45 publications

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“…However, if high shear stresses during energetic tides or strong storms are present, the fluid mud could have been trapped in the wave boundary layer, allowing it to slide downslope onto the foreset (Walsh & Nittrouer, 2003; Jaramillo et al, 2009). The fluid mud flow would have terminated on the slope when its shear strength exceeded the shear stress, which is anticipated to decrease rapidly as the wave and tide energy dissipated in deeper water (Cacchione et al, 1995;Traykovski et al, 2000;Jaramillo et al, 2009;Tang et al, 2023). The squishy and often deformed nature of the thick fluid mud may be a result of dewatering of highwater-content and high-pore-pressure fluid Facies Association 2 (FA2): Subaqueous platform deposits Observations: The subaqueous platform deposits reach only 4 m in thickness and consist of two component facies associations: FA2a, and FA2b (Table 2; Figs 3 and 9).…”

Section: Facies Associationsmentioning

confidence: 99%

Impact of wave, tides and fluid mud on fluvial discharge across a compound clinoform (Pliocene Orinoco Delta)

Osman,

Steel,

Ramsook

et al. 2024

Sedimentology

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Compound clinoforms are well‐recognized in modern large muddy deltas and in some ancient deltas, but there is still a lack of understanding regarding their lithology variations and the process by which sand from the shoreline clinothem reaches the subaqueous clinothem foresets that are sometimes 100 km away. Net‐to‐gross, thickness and facies association evaluation show overall coarsening‐upward through a 191 m thick exposure of the late Pliocene Orinoco, Lower Morne L'Enfer Formation, with a distinct tripartite lithology distribution. The subaqueous clinothem records a lower, relatively muddy coarsening‐upward interval, 112 m thick, with net‐to‐gross increasing from zero to 60%. On the lower delta front, zero net sand units show graded beds of silt and mud with occasional spring–neap rhythmites, strongly suggesting gravity flows influenced by tidal currents. These foreset beds are overlain by structureless very fine sand, interbedded with deformed wavy to lenticular, grey fluid mud layers that rapidly accumulated near the subaqueous clinoform rollover point. The tidally dominated subaqueous platform (subaqueous delta topset), 1 to 4 m thick, shows zero net sand units with anomalously high mud content, >70%, due to the high near‐bed suspended sediment concentration of externally derived fluid mud that migrated littorally alongshore from the Amazon Delta. The interaction of freshwater river flood discharge with fluid‐mud banks gave rise to density stratification with fine sand hypopycnally dispersing as a turbulent layer above the denser fluid‐mud carpet. The shoreline clinothem (<8 m thick) has high net‐to‐gross, >85%, attributed to winnowing of sediment by waves and tides. Utilizing net‐to‐gross trends and facies changes provide useful criteria to identify compound clinoforms in the rock record. The Orinoco Delta deposits, however, are unusual, since fluid mud hinders sand deposition on the platform, allowing for easy identification of platform facies and a clear distinction between the subaqueous and shoreline clinothem in outcrop.

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Section: Facies Associationsmentioning

confidence: 99%

Impact of wave, tides and fluid mud on fluvial discharge across a compound clinoform (Pliocene Orinoco Delta)

Osman,

Steel,

Ramsook

et al. 2024

Sedimentology

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“…During storm events, the combined forces of strong waves and tidal currents can erode the bed, resuspend and retain sediment near the bed, ultimately resulting in the formation of a fluid sediment layer. This particular form of fluid mud is commonly known as wavesupported fluid mud and is frequently observed on the continental shelf and in estuarine subaqueous deltas (e.g., Hale and Ogston, 2015;Liu et al, 2022;Tang et al, 2023). Prolonged wave action can lead to an increase in excess pore pressure within the bed, resulting in a decrease in bed strength and localized liquefaction (Jeng, 2013;Anderson et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Fluid mud induced by periodic tidal advection and fine-grained sediment settling in the Yangtze estuary

Wu,

Tang,

et al. 2023

Front. Mar. Sci.

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This study presents in-situ observations of fluid mud in the Yangtze Estuary via a bottom tripod. Six occurrences of periodic fluid muds (F1-F6) were observed at high slack water, with suspended sediment concentration (SSC) exceeding 10 kg/m3. The thickness of the fluid mud varied across the six occurrences, reaching a maximum of 0.32m. Notably, temperature and salinity anomalies were observed within the fluid mud. The formation of fluid mud was found to be influenced by turbulence, with turbulence kinetic energy (TKE) below 5×10-4 m2/s2 favoring settling as the primary cause of formation. The critical shear stress (τcw) for fluid mud formation was estimated to be approximately 0.09 Pa. The formation of fluid muds during early tidal cycles was attributed to liquefaction and bed erosion resulting from strong waves. However, in most cases, the wave energy was insufficient for erosion, suggesting that advection played a role in sediment supply during the subsequent tide cycles. The increased cross-channel current velocity during flood facilitated the lateral transport of a significant amount of eroded sediment from shallow water into the channel. Due to its short duration, the fluid mud layer was entrained by the current before consolidation. Enhanced turbulence led to the breakdown of fluid mud at the early ebb. The critical τcw for fluid mud breakdown depended on the density and duration of the fluid mud, with a maximum value of up to 0.70 Pa. The absence of the fluid mud layer during low slack water and neap tide was associated with a reduction in advection and tidal pumping, disrupting the original sediment balance between supply and demand. These data provide valuable insights into the formation and breakdown of fluid mud, contributing to estuarine hydrodynamic modeling studies and enhancing the understanding of estuary dynamics.

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Subaqueous deltas in the stratigraphic record: Catching up with the marine geologists

Steel,

Osman,

Rossi

et al. 2024

Earth-Science Reviews

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Formation and transport of fluid mud triggered by typhoon events in front of the subaqueous Changjiang Delta

Cited by 7 publications

References 45 publications

Impact of wave, tides and fluid mud on fluvial discharge across a compound clinoform (Pliocene Orinoco Delta)

Impact of wave, tides and fluid mud on fluvial discharge across a compound clinoform (Pliocene Orinoco Delta)

Fluid mud induced by periodic tidal advection and fine-grained sediment settling in the Yangtze estuary

Subaqueous deltas in the stratigraphic record: Catching up with the marine geologists

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