Geotechnical characteristics and slope stability analysis of Beaufort Sea marine sediments, offshore Yukon and Northwest Territories: methodology and results

MacKillop, K; Ouellette, D.; King, E.L.; Blasco, Steve

doi:10.4095/329427

Cited by 1 publication

(5 citation statements)

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“…Bulk density information is sparse in the Beaufort continental slope area (Blasco et al, 2013). According to the recent result by MacKillop et al (2022), the estimated bulk density is even slightly smaller than 1.72 g/cm 3 of surficial sedimentary core 2010804-0069 (~4 m in core length) retrieved close to MV420. At water depths ranging from 75 m to 600 m, surficial sedimentary core (2-7 m in core length) retrieved at five sites closed to MV282 shows 1.59-1.71 g/cm 3 in bulk The estimated bulk density of sediments by the cable release by controlled amount in Observation C2 are represented as a bar (thick line for average value and box for ± standard deviation) with depth (thickness of a bar) (Table 2).…”

Section: Sediment Bulk Densitymentioning

confidence: 94%

“…At water depths ranging from 75 m to 600 m, surficial sedimentary core (2-7 m in core length) retrieved at five sites closed to MV282 shows 1.59-1.71 g/cm 3 in bulk The estimated bulk density of sediments by the cable release by controlled amount in Observation C2 are represented as a bar (thick line for average value and box for ± standard deviation) with depth (thickness of a bar) (Table 2). Compilation of Deep Sea Drilling Project data (black dots with blue line for average) is also shown (Tenzer and Gladkikh, 2014) Surficial data (red line) from areas close to MV420 are depicted (Blasco et al, 2013;MacKillop et al, 2022). The estimated bulk density is slightly lower than the global data with depth.…”

Section: Sediment Bulk Densitymentioning

confidence: 97%

“…The inset exhibits regional bathymetry of the Canadian Beaufort Sea and the location of three mud volcanoes (red circles): MV282, MV420 (closed), and MV740 (Paull et al, 2015). The comparison site for sediment bulk density is 2010804-0069 (orange square) (MacKillop et al, 2022). The subsea permafrost limit is considered to follow an isobath of water depth ~100 m below sea level (dashed green line) (Taylor et al, 2013).…”

Section: Geological Settingmentioning

confidence: 99%

“…All parameters except ρ are observed at Site A served as a control site having the same water depth as MV420, where the sediment core was retrieved. The bulk density of 1.72 g/cm 3 is adopted from Station 2010804-0069, away from Site A by ~20 km (Figure 1 inset) (MacKillop et al, 2022) because no direct measurement of the bulk density for the sediment core at Site A was conducted.…”

Section: Thermal Conductivitymentioning

confidence: 99%

“…Reading thermal conductivity was possible only in the lower part of the core, possibly because sediment with high porosity and water content on the seafloor may hinder contact with the needle probe with the sediment. The water content of Core 2010804-0069 decreases with depth from ~120% at the seafloor to ~100% at 100 cmbsf (MacKillop et al, 2022). Finally, the thermal conductivity of 0.985 W/m/K was estimated using laboratory measurements from Site A.…”

Section: Thermal Conductivity and Marine Heat Flow At The Control Sitementioning

confidence: 99%

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Thermal structure and sediment bulk density of the MV420 mud volcano on the continental slope of the Canadian Beaufort Sea and its implications for the plumbing system

et al. 2022

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The shallow migration path of mudflow of the mud volcano MV420 on the continental slope of the Canadian Beaufort Sea is investigated in terms of thermal and geotechnical characteristics. MV420 is a nearly flat topped active mud volcano that emits methane and fluidized mud. Its top is at a depth of water of 420 m, within the gas hydrate stability zone. During the summer 2017 IBRV Araon expedition, several measurements of marine heat flow were conducted in the area of juvenile mud mound/pond morphologies identified by multibeam bathymetry and backscatter intensity images obtained by the Monterey Bay Aquarium Research Institute’s autonomous underwater vehicle. The heat probe (a gravity corer with temperature, pressure, and tilt sensors) appeared to penetrate to a depth of >70 m below the seafloor. The sediment bulk density in the mudflow migration path of MV420, estimated by pressure change with controlled stretches of a winch cable, was 1.56 g/cm3. The subsurface temperature reaches up to 18°C and profiles show that the maximum local temperature occurs from 20 to 40 m below the seafloor, implying substantial vertical variability of geothermal gradients. Our finding of large positive and small negative geothermal gradients above and below the depth of the local temperature maximum may represent stagnant hot mud along the mudflow migration path, indicating a pulsative eruption of the mudflow. Gas hydrate is stable only within a few meter thick layer near the seafloor above the path because of the cold bottom water (0.4°C) covering the top of the mud volcano. Furthermore, the thermal conductivity of 0.939 W/m/K and the marine heat flow of 22.5 mW/m2 at a control site outside MV420 is estimated as the background heat flow in the slope, for which little data exists.

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Section: Sediment Bulk Densitymentioning

confidence: 94%