Climate-Induced Turbidity Current Activity in NW-African Canyon Systems

Henrich, Rüdiger; Hanebuth, Till J J; Cherubini, Yvonne; Krastel, Sebastian; Pierau, Roberto; Zühlsdorff, Christine

doi:10.1007/978-90-481-3071-9_37

Cited by 4 publications

(5 citation statements)

References 19 publications

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“…Coarse‐grained sediments with a good porosity and permeability tend to be deposited on the levees on both sides of the canyon. This has also been discovered through gas hydrate drilling and sampling in the Gulf of Mexico, the Krishna‐Godavari (KG) Basin, and the Nankai Trough (Boswell et al, 2012; Boswell, Collett, et al, 2012; Fujii et al, 2015; Henrich, Hanebuth, Cherubini, Krastel, & Lee, 2010; Waite, Jang, Collett, & Kumar, 2019). The identified gas hydrate accumulation in the study area is close to Hainan Island, so it has a sufficient provenance and a short transport distance, and thus, relatively coarser‐grained sediments tend to be deposited in the channel‐levee system.…”

Section: Discussionmentioning

confidence: 91%

Gas hydrate accumulation in shelf break setting: Example from the Qiongdongnan Basin in the northern slope of the South China Sea

Zhang

Deng

et al. 2021

Geological Journal

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Based on interpretation and inversion of high‐resolution seismic data, a previously undocumented occurrence of pore‐filled gas hydrates that are associated with a submarine canyon system was discovered in the shelf break of the north‐east Qiongdongnan Basin (QDNB) in the northern South China Sea (SCS). Continuous bottom simulating reflections (BSRs) were recognized in the submarine striking NW‐SE ridges along the shelf break. The two‐way travel times (TWTs) of the BSRs are about 200–250 ms below the sea floor and the burial depths are mapped at ~180–225 mbsf after time‐depth conversion. The distribution of the enhanced reflections (ERs) and acoustic blanking zone overlying the BSRs indicate possible pore‐filled gas hydrate enrichment. ERs have been commonly observed immediately below the BSRs, indicating the accumulation of free gas, which exhibits distinct amplitude versus offset (AVO) anomalies. The acoustic impedance inversion results show that the gas hydrate saturation is 20–50%, and the thickness of the gas hydrate‐bearing layers is usually ~10–40 m, with a maximum thickness of up to ~90 m in local regions. Large‐scale listric faults originating from the deep sag connect the hydrocarbon source region and the shallow gas hydrate stability zone (GHSZ) and act as migration pathways for biogenic gas and potentially thermogenic gas. In addition, hydrocarbons may also be transported into the GHSZ along the sidewalls of the canyon. Canyon incision is believed to cause the increase in the burial depth of the BSRs on the flank of the ridge toward the base of the channel and thereby to trap the hydrocarbons migrating along the sidewall in permeable beds due to the decrease in permeability caused by the gas hydrate accumulation, resulting in the occurrence of ERs immediately below the BSRs. It is speculated that in the channel‐levee system, the coarse‐grained sediments should be deposited within the GHSZ, and the reservoir's physical properties are conducive to the wide distribution and enrichment of pore‐filled gas hydrates in the shelf break of the northern QDNB.

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Section: Discussionmentioning

confidence: 91%

Gas hydrate accumulation in shelf break setting: Example from the Qiongdongnan Basin in the northern slope of the South China Sea

Zhang

Deng

et al. 2021

Geological Journal

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“…The main study area of this contribution is the distal Timiris Canyon (Fig. 2b, Henrich et al, 2009). In the upper course of this sector the canyon runs SE-NW incising 90 m deep into the seafloor, whereas in the lower course the canyon turns westward and becomes much shallower towards its end with an incision depth of less than 20 m. Locations of cores comprise (1) a NE-SW core traverse in the upper sector: Core GeoB 9624 recovered in a northeastern levee position (3894 m water depth), Core GeoB 9623 recovered from a 40-50 m high elevated terrace inside the canyon (3940 m water depth), and Core GeoB 9626 taken from a shallow depression incising the southwestern levee (3926 m water depth).…”

Section: Regional Settingsmentioning

confidence: 99%

Climate and sea level induced turbidite activity in a canyon system offshore the hyperarid Western Sahara (Mauritania): The Timiris Canyon

2010

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“…At mid-and lower latitudes the glacial influence is less evident and the database less substantial, but here also there is evidence of a climate control on SMF (e.g. Gee et al 1999;Henrich et al 2009). …”

Section: Submarine Mass Failuresmentioning

confidence: 60%

“…Both are associated with changes in eustatic sea level, when this was either rising or falling rapidly. Farther south, off Mauritania, turbidite complexes are also clearly climate controlled (Henrich et al 2009). There is a high frequency of failure during deglaciation, when sea level was rising, through remobilization of large-scale aeolian dune fields that had expanded to the shelf edge during glacial sea-level lows.…”

Section: (Iii) Non-glaciated Marginsmentioning

confidence: 99%

Submarine mass failures as tsunami sources: their climate control

Tappin

2010

Phil. Trans. R. Soc. A.

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Recent research on submarine mass failures (SMFs) shows that they are a source of hazardous tsunamis, with the tsunami magnitude mainly dependent on water depth of failure, SMF volume and failure mechanism, cohesive slump or fragmental landslide. A major control on the mechanism of SMFs is the sediment type, together with its post-depositional alteration. The type of sediment, fine- or coarse-grained, its rate of deposition together with post-depositional processes may all be influenced by climate. Post-depositional processes, termed sediment ‘preconditioning’, are known to promote instability and failure. Climate may also control the triggering of SMFs, for example through earthquake loading or cyclic loading from storm waves or tides. Instantaneous triggering by other mechanisms such as fluid overpressuring and hydrate instability is controversial, but is here considered unlikely. However, these mechanisms are known to promote sediment instability. SMFs occur in numerous environments, including the open continental shelf, submarine canyon/fan systems, fjords, active river deltas and convergent margins. In all these environments there is a latitudinal variation in the scale of SMFs. The database is limited, but the greatest climate influence appears to be in high latitudes where glacial/interglacial cyclicity has considerable control on sedimentation, preconditioning and triggering. Consideration of the different types of SMFs in the context of their climate controls provides additional insight into their potential hazard in sourcing tsunamis. For example, in the Atlantic, where SMFs are common, the tsunami hazard under the present-day climate may not be as great as their common occurrence suggests.

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Climate-Induced Turbidity Current Activity in NW-African Canyon Systems

Cited by 4 publications

References 19 publications

Gas hydrate accumulation in shelf break setting: Example from the Qiongdongnan Basin in the northern slope of the South China Sea

Gas hydrate accumulation in shelf break setting: Example from the Qiongdongnan Basin in the northern slope of the South China Sea

Climate and sea level induced turbidite activity in a canyon system offshore the hyperarid Western Sahara (Mauritania): The Timiris Canyon

Submarine mass failures as tsunami sources: their climate control

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