Channel‐lobe transition zone development in tectonically active settings: Implications for hybrid bed development

Brooks, Hannah L.; Itô, Makoto; Zuchuat, Valentin; Peakall, Jeff; Hodgson, David M.

doi:10.1002/dep2.180

Cited by 14 publications

(15 citation statements)

References 167 publications

(429 reference statements)

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“…The preservation of a thicker stratigraphic record for CLTZs has been explained by high aggradation rates (e.g., Pemberton et al, 2016; Figure 10), tectonically-active settings (Ito, 2008;Mansor and Amir Hassan, 2021;Brooks et al, 2022), rapid abandonment or avulsion of feeder channels before erosion into the CLTZ (e.g., Hofstra et al, 2015;Brooks et al, 2018), or a large-scale passive margin setting allowing more net aggradation (Navarro and Arnott, 2020). Nonetheless, these studies also interpret lobes and channel-fills as part of the stratigraphic succession, which points to an aggrading and interfingering succession where the CLTZ is relatively fixed, and preserved as surfaces and thinner stratigraphic units as part of a thicker succession.…”

Section: Exhumed Thin Cltzs (< 10 M Thick)mentioning

confidence: 99%

“…The transfer of CLTZs into the stratigraphic record has been interpreted in several outcrop studies. Based on these examples, recognition criteria for CLTZs in the rock record include: a typically thin stratigraphic expression; amalgamated erosional features; coarse-grained lag deposits; aggradational bedforms (i.e., subcritical sediment waves); soft-sediment deformation; interfingered or juxtaposed erosional and depositional elements; and sand-rich hybrid beds in proximal lobes (e.g., Bravo and Robles, 1995;Ito, 2008;Pyles et al, 2014;Van der Merwe et al, 2014;Hofstra et al, 2015;Brooks et al, 2018;Hofstra et al, 2018;Brooks et al, 2022). However, recognition criteria for distinguishing CLTZs and CMEZs in the rock record have not been established.…”

Section: Dynamic Settings and Building A Stratigraphic Recordmentioning

confidence: 99%

“…Detailed outcrop research on CLTZs has primarily focused on large, relatively tectonically-quiescent basins associated with mature passive margins or thermal sag basins, and influenced by glacial-interglacial cycles, such as the Karoo Basin in South Africa (e.g., Van der Merwe et al, 2014;Hofstra et al, 2015;Brooks et al, 2018). Therefore, it is important to understand if these same models can be applied to tectonically-active basins (e.g., Mansor and Amir Hassan, 2021;Brooks et al, 2022), such as forearc or retroarc foreland basins, formed in different climatic conditions in both modern environments and in the rock record. Indeed, tectonically-active basin-fills are likely to host CMEZs given the steeper slopes.…”

Section: Future Opportunities For Channel Mouth and Cltz Researchmentioning

confidence: 99%

“…There is a growing literature on CLTZs interpreted from ancient outcrops (see compilation by Navarro and Arnott, 2020), with recognition criteria proposed to support links between sedimentary processes and deposits (e.g., Bravo and Robles, 1995;Ito, 2008;Pyles et al, 2014;Hofstra et al, 2015;Pemberton et al, 2016;Postma et al, 2016;Brooks et al, 2018;Hofstra et al, 2018;Postma et al, 2021). Preserved stratigraphic successions of interpreted CLTZs range from thick successions of aggradational beds in close association with scour-fill features (e.g., Pemberton et al, 2016;Brooks et al, 2018;Mansor and Amir Hassan, 2021;Brooks et al, 2022) to single surfaces that separate lobes from overlying channel-levee systems (e.g., Gardner et al, 2003;Hodgson et al, 2016). The wide range of expressions and dimensions (Navarro and Arnott, 2020) point to a number of parameters and configurations that control the transfer, and preservation, of channel mouth settings into the rock record.…”

Section: Introductionmentioning

confidence: 99%

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Submarine Channel Mouth Settings: Processes, Geomorphology, and Deposits

2022

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Observations from the modern seafloor that suggest turbidity currents tend to erode as they lose channel-levee confinement, rather than decelerating and depositing their sediment load, has driven investigations into sediment gravity flow behaviour at the mouth of submarine channels. Commonly, channel mouth settings coincide with areas of gradient change and play a vital role in the transfer of sediment through deep-water systems. Channel mouth settings are widely referred to as the submarine channel-lobe transition zone (CLTZ) where well-defined channel-levees are separated from well-defined lobes, and are associated with an assemblage of erosional and depositional bedforms (e.g., scours and scour fields, sediment waves, incipient channels). Motivated by recently published datasets, we reviewed modern seafloor studies, which suggest that a wide range of channel mouth configurations exist. These include traditional CLTZs, plunge pools, and distinctive long and flared tracts between channels and lobes, which we recognise with the new term channel mouth expansion zones (CMEZs). In order to understand the morphodynamic differences between types of channel mouth settings, we review insights from physical experiments that have focussed on understanding changes in process behaviour as flows exit channels. We integrate field observations and numerical modelling that offer insight into flow behaviours in channel mouth settings. From this analysis, we propose four types of channel mouth setting: 1) supercritical CMEZs on slopes; 2) plunge pools at steep slope breaks with high incoming supercritical Froude numbers; 3) CLTZs with arrays of hydraulic jumps at slope breaks with incoming supercritical Froude numbers closer to unity; and, 4) subcritical CLTZs associated with slope breaks and/or flow expansion. Identification of the stratigraphic record of channel mouth settings is complicated by the propagation, and avulsion, of channels. Nonetheless, recent studies from ancient outcrop and subsurface systems have highlighted the dynamic evolution of interpreted CLTZs, which range from composite erosion surfaces, to tens of metres thick stratigraphic records. We propose that some examples be reconsidered as exhumed CMEZs.

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Section: Exhumed Thin Cltzs (< 10 M Thick)mentioning

confidence: 99%

Section: Dynamic Settings and Building A Stratigraphic Recordmentioning

confidence: 99%

Section: Future Opportunities For Channel Mouth and Cltz Researchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Submarine Channel Mouth Settings: Processes, Geomorphology, and Deposits

2022

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“…Increasing CLTZs have been found in ancient stratigraphic records (e.g. Baas et al, 2021;Brooks et al, 2022;Brooks, Hodgson, Brunt, Peakall, Hofstra, & Flint, 2018;Brooks, Hodgson, Brunt, Peakall, Poyatos-Moré, & Flint, 2018;Chen et al, 2021;Hansen et al, 2021;Hofstra et al, 2015Hofstra et al, , 2018Pohl et al, 2022;Yang et al, 2022) and in modern environments (e.g. Luo et al, 2021;Zhou et al, 2021).…”

Section: Introductionmentioning

confidence: 98%

Architecture, formation and implication of active structure‐controlled intraslope channel system southeast offshore Sendai, Tohoku, Japan

et al. 2022

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Located off the Pacific coast of central Tohoku (NE Japan), the Ishinomaki slope channel (ISC) provides an excellent opportunity to study a structure‐controlled intraslope channel and downslope sedimentation along the active margin. The seismic reflection data across ISC show an extensive basal surface and overlying channel complexes between the basement structures of the Abukuma ridge to the south and Kitakami massif to the north, indicating that the formation of the intraslope basin, channelization of ISC and sedimentation of the downstream channel‐lobe transition zone (CLTZ) are very likely to be structure‐controlled. The oblique channel stacking pattern, faulting of the seafloor and subsurface Abukuma ridge in the upper and lower domains of ISC, collectively suggest that ISC has migrated northward and is currently under the influence of active compression. Differences in styles of accommodation space between the upper and lower domains of ISC suggest that differential subsidence occurred along the strike‐slip tectonic line. Based on the regional strike‐slip tectonic line, we propose that a Kitakami‐Abukuma ridge existed before the formation of ISC. The strike‐slip faulting divided the Kitakami‐Abukuma ridge into the Kitakami massif to the north and the Abukuma ridge to the south, and an intervening fault trough as the precursor of the intraslope basin and ISC. As the subduction of the Pacific Plate and associated compressional events continued, the Abukuma ridge was reactivated to narrow the intraslope basin into a confined channel. Located near the epicentre of the devastating 2011 Tohoku earthquake event, the ISC, downstream CLTZ and underlying intraslope basin provide information on active basement structure and the evolving sediment routing system on the tectonically active margin.

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Flow dynamics as Froude‐supercritical turbidity currents encounter metre‐scale slope minibasin topography

Englert,

Hubbard,

Romans

et al. 2023

The Depositional Record

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Seafloor topography can affect turbidity current dynamics on deep‐water slopes, significantly influencing the dispersal of sediment. Despite the common occurrence of topographic complexity, there are few detailed investigations of topographic interactions and their effect on downslope flow evolution in intraslope environments. In this study, the sedimentology and architecture of an Upper Cretaceous intraslope fan succession deposited within an extensional, fault‐bound minibasin are described from a rare, well‐exposed, near‐continuous, oblique depositional‐dip outcrop of the Tres Pasos Formation, Chile. The 2 to 8 m thick studied interval transitions downslope from high‐energy heterolithic strata, including metre‐scale steep‐faced scours, to non‐amalgamated thick‐bedded sandstones. Abrupt increases in sandstone percentage, sandstone bed thickness and grain size occur on the hangingwall blocks of south‐east and north‐east‐dipping normal faults that bound the minibasin. Sandstone beds are dominated by backset or wavy low‐angle stratification proximally, contain compositional banding near faults, and are characterised by increased proportions of planar laminated and structureless turbidite divisions downslope along the transect. Experimental observations of turbidity current interactions with topography are synthesised into a qualitative framework, which is used to interpret flow processes and characteristics from deposit trends. The results reconstruct the response of Froude‐supercritical, stratified turbidity currents with denser basal layers when encountering metre‐scale fault scarps. The analysis shows that metre‐scale topographic features can substantially alter the flow properties of stratified turbidity currents, and their downslope flow evolution to include the development of transitional, depositional and flow‐stripped sediment gravity currents. However, in comparison to base‐of‐slope settings, overall flow conditions are interpreted to be more uniform over slope breaks and zones of flow expansion in a partially confined intraslope environment. These findings have considerable implications for understanding flow response to similar scale morphological features on the seafloor and the potential for flow transformations in intraslope settings.

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Channel‐lobe transition zone development in tectonically active settings: Implications for hybrid bed development

Cited by 14 publications

References 167 publications

Submarine Channel Mouth Settings: Processes, Geomorphology, and Deposits

Submarine Channel Mouth Settings: Processes, Geomorphology, and Deposits

Architecture, formation and implication of active structure‐controlled intraslope channel system southeast offshore Sendai, Tohoku, Japan

Flow dynamics as Froude‐supercritical turbidity currents encounter metre‐scale slope minibasin topography

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