Gas migration pathways and slope failures in the Danube Fan, Black Sea

Hillman, Jess; Klaucke, Ingo; Bialas, J.; Feldman, Howard R.; Drexler, Tina M.; Awwiller, David N.; Atgin, O.; Çifçi, Günay; Badhani, Shray

doi:10.1016/j.marpetgeo.2018.03.025

Cited by 29 publications

(34 citation statements)

References 83 publications

(171 reference statements)

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“…One could infer that the MTDs are therefore less permeable than hemipelagic sediments (as e.g. described by Hillman et al, 2018a). These MTDs almost all originate at erosional headscarps at the slope edge in water depths ∼120-200 m. The MTDs cover deeper sediment-wave topography but their own rough surface still impacts gas migration.…”

Section: Mass-transport Depositsmentioning

confidence: 90%

“…Over the course of the past 20 years of research on gas hydrates conducted in the Black Sea, numerous active gas expulsion sites, mud volcanoes, and indicators for gas and hydrate distribution have been found (e.g., Ergün et al, 2002;Vassilev and Dimitrov 2002;Greinert et al, 2006;Klaucke et al, 2006;Naudts et al, 2006;Popescu et al, 2007;Sahling et al, 2009;Greinert et al, 2010;Pape et al, 2010;Starostenko et al, 2010;Römer et al, 2012;Römer et al, 2019;Körber et al, 2014;Hillman et al, 2018a;Wu et al, 2019;Zander et al, 2019).…”

Section: Studies On Gas Hydrates and Gas Venting In The Black Seamentioning

confidence: 99%

“…The S1 to S5 channels are linked to the Danube river, whereas the N1 to N4 channels have been linked to the Dnepr river (Wong et al, 1994;Wong et al, 1997;Winguth et al, 2000). The sediments found in the two associated deep-sea fans consist of mainly fine-grained turbidites and form stacks of alternating channel and levees deposits interspersed with mass-transport deposits (Popescu et al, 2001;Popescu et al, 2004;Hillman et al, 2018a). The deep-sea fans began to develop ∼900 ka BP (Winguth et al, 2000) and the Viteaz Channel is the most recently active channel.…”

Section: Geological Backgroundmentioning

confidence: 99%

“…A high-resolution subset of 2-D MCS lines was acquired but with a smaller-sized GI gun (1.5 L, 90 in 3 ) and shorter streamer (237.5 m active length, 76 channels). Additional high-resolution 3-D seismic data were acquired with the P-cable system in two regions linked to the SUGAR program activities (details see e.g., Zander et al, 2017;Hillman et al, 2018a;Hillman et al, 2018b;Bialas et al, 2020). Processing of the 2-D regional and high-res MCS data included geometry definition and sorting to common-mid-point locations, band-pass filtering (10-180 Hz), followed by velocity analysis with normal move-out (NMO) correction, and stacking.…”

Section: Multichannel Seismic Datamentioning

confidence: 99%

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Controls on Gas Emission Distribution on the Continental Slope of the Western Black Sea

et al. 2021

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The continental slopes of the Black Sea show abundant manifestations of gas seepage in water depth of <720 m, but underlying controls are still not fully understood. Here, we investigate gas seepage along the Bulgarian and Romanian Black Sea margin using acoustic multibeam water column, bathymetry, backscatter, and sub-bottom profiler data to determine linkages between sub-seafloor structures, seafloor gas seeps, and gas discharge into the water column. More than 10,000 seepage sites over an area of ∼3,000 km2 were identified. The maximum water depth of gas seepage is controlled by the onset of the structure I gas hydrate stability zone in ∼720 m depth. However, gas seepage is not randomly distributed elsewhere. We classify three factors controlling on gas seepage locations into depositional, erosional, and tectonic factors. Depositional factors are associated with regionally occurring sediment waves forming focusing effects and mass-transport deposits (MTDs) with limited sediment drape. Elongated seafloor depressions linked to faulting and gas seepage develop at the base between adjacent sediment waves. The elongated depressions become progressively wider and deeper toward shallow water depths and culminate in some locations into clusters of pockmarks. MTDs cover larger regions and level out paleo-topography. Their surface morphology results in fault-like deformation patterns of the sediment drape on top of the MTDs that is locally utilized for gas migration. Erosional factors are seen along channels and canyons as well as slope failures, where gas discharge occurs along head-scarps and ridges. Sediment that was removed by slope failures cover larger regions down-slope. Those regions are devoid of gas seepage either by forming impermeable barriers to gas migration or by removal of the formerly gas-rich sediments. Deep-rooted tectonic control on gas migration is seen in the eastern study region with wide-spread normal faulting promoting gas migration. Overall, gas seepage is widespread along the margin. Gas migration appears more vigorous in shallow waters below ∼160 m water depth, but the number of flare sites is not necessarily an indicator of the total volume of gas released.

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Section: Mass-transport Depositsmentioning

confidence: 90%

Section: Studies On Gas Hydrates and Gas Venting In The Black Seamentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Multichannel Seismic Datamentioning

confidence: 99%

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Controls on Gas Emission Distribution on the Continental Slope of the Western Black Sea

et al. 2021

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“…The Chile Triple Junction (CTJ) area is a spectacular example of tectonic erosion (e.g., [39]). Even though many investigations are associated with seepage identification and gas expulsion quantification (gas bubbles) (e.g., [29,38,[40][41][42]), there are few cases where the objective was to estimate the size of the gas source, as concentrations of gas hydrate and free gas [43].…”

Section: Introductionmentioning

confidence: 99%

Gas Hydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction

et al. 2019

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Large amounts of gas hydrate are present in marine sediments offshore Taitao Peninsula, near the Chile Triple Junction. Here, marine sediments on the forearc contain carbon that is converted to methane in a regime of very high heat flow and intense rock deformation above the downgoing oceanic spreading ridge separating the Nazca and Antarctic plates. This regime enables vigorous fluid migration. Here, we present an analysis of the spatial distribution, concentration, estimate of gas-phases (gas hydrate and free gas) and geothermal gradients in the accretionary prism, and forearc sediments offshore Taitao (45.5°–47° S). Velocity analysis of Seismic Profile RC2901-751 indicates gas hydrate concentration values <10% of the total rock volume and extremely high geothermal gradients (<190 °C·km−1). Gas hydrates are located in shallow sediments (90–280 m below the seafloor). The large amount of hydrate and free gas estimated (7.21 × 1011 m3 and 4.1 × 1010 m3; respectively), the high seismicity, the mechanically unstable nature of the sediments, and the anomalous conditions of the geothermal gradient set the stage for potentially massive releases of methane to the ocean, mainly through hydrate dissociation and/or migration directly to the seabed through faults. We conclude that the Chile Triple Junction is an important methane seepage area and should be the focus of novel geological, oceanographic, and ecological research.

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Gas hydrate/free gas migration pathways in submarine slope failures: East Indian Margin

2021

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Gas migration pathways and slope failures in the Danube Fan, Black Sea

Cited by 29 publications

References 83 publications

Controls on Gas Emission Distribution on the Continental Slope of the Western Black Sea

Controls on Gas Emission Distribution on the Continental Slope of the Western Black Sea

Gas Hydrate Estimate in an Area of Deformation and High Heat Flow at the Chile Triple Junction

Gas hydrate/free gas migration pathways in submarine slope failures: East Indian Margin

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