Gerd G. Kopper 60

Bohrmann, Hans

doi:10.1007/s11616-001-0123-1

Cited by 2 publications

(4 citation statements)

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“…The study area is located on the continental slope offshore Georgia in the eastern Black Sea [ Bohrmann et al , 2007]. This region is subject to active compressional deformation resulting from the northward movement of the Arabian plate and westward movement of the Anatolian Block [ Meredith and Egan , 2002].…”

Section: Study Areamentioning

confidence: 99%

“… Klaucke et al [2005, 2006] described in detail the two studied seep areas Batumi and Kobuleti, which are located between 840 and 870 m water depth on the Kobuleti Ridge. The seeps are characterized by gas hydrate deposits and authigenic carbonates in the sediments which cause high backscatter in side scan data [ Bohrmann et al , 2007]. In addition, 40 to 50 gas flares are seen as high backscatter spots in the processed side scan mosaics.…”

Section: Study Areamentioning

confidence: 99%

“…Merian as well as the ROV Quest . The study was carried out during cruise M 72/3a in 2007 at the Batumi and Kobuleti Seep located at about 860 m water depth offshore Georgia in the eastern Black Sea [ Bohrmann et al , 2007]. At these sites, evidence for gas seepage was found during earlier deep‐towed side scan sonar surveys [ Klaucke et al , 2005, 2006].…”

Section: Introductionmentioning

confidence: 99%

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Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Nikolovska

Sahling

Bohrmann

2008

Geochem Geophys Geosyst

113

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[1] Detailed acoustic investigation of bubble streams rising from the seafloor were conducted during R/V Meteor cruise M72/3a at a deep submarine hydrocarbon seep environment. The area is located offshore Georgia (eastern part of the Black Sea) at a water depth between 840 m and 870 m. The sediment echosounder Parasound DS-3/P70 was used for detecting bubbles in the water column that causes strong backscatter in the echographs (''flares''). Employing the swath echsounder Kongsberg EM710 flares in the water column were mapped along the entire swath width of approximately 1000 m at high spatial resolution. The exact location of the flares could be extracted manually. Subsequently, the horizontally looking sonar Kongsberg digital telemetry MS1000 mounted on a remotely operated vehicle (ROV) was utilized to quantify the flux of bubbles. A model was developed that is based on the principle of finding the ''acoustic mass'' in order to quantify the bubble flux at various seeps. The acoustic approach from the backscatter data of the ROV sonar resulted in bubble fluxes in the range of 0.01 to 5.5 L/min (corresponding to 0.037 to 20.5 mol CH 4 /min) at in situ conditions ($850 m water depth, $9°C). Independent flux estimations using a funnel-shaped device showed that the acoustic model consistently produced lower values but the offset is less than 12%. Furthermore, the deviation decreased with increasing flux rates. A field of bubble streams was scanned three times from different directions in order to reveal the reproducibility of the method. Flux estimations yielded consistent fluxes of about 2 l/min (7.4 mol CH 4 /min) with variations of less than 10%. Although gas emissions have been found at many sites at the seafloor in a range of geological settings, the amount of escaping gas is still largely unknown. With this study presenting a novel method of quantifying bubble fluxes employing a horizontally looking sonar system, it is intended to contribute to the global effort of better constraining bubble fluxes at deep-sea settings.

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Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Nikolovska

Sahling

Bohrmann

2008

Geochem Geophys Geosyst

113

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“… (a) Location of the Fåvne vent field and other confirmed and inferred hydrothermal vent fields within the Norwegian and Greenland Seas (Beaulieu & Szafrański, 2020; Bohrmann, 2022). (b) Regional setting of the ridge segment hosting the Fåvne vent field on the Mohns Ridge.…”

Section: Introductionmentioning

confidence: 99%

Iron Oxyhydroxide‐Rich Hydrothermal Deposits at the High‐Temperature Fåvne Vent Field, Mohns Ridge

Gini,

Jamieson,

Reeves

et al. 2024

Geochem Geophys Geosyst

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The recently discovered Fåvne vent field, located at 3,040 m depth on the slow‐spreading Mohns mid‐ocean ridge between Greenland and Norway, is a high‐temperature (≥250°C) vent field that is characterized by Fe oxyhydroxide‐rich and S‐poor chimneys and mounds. The vent field is located on both the hanging wall and footwall of a normal fault with a ∼1.5 km throw that forms the western edge of the ∼20 km wide ridge axial valley. Data collected during exploration of the site using a remotely operated vehicle as well as mineralogical and geochemical analyses of rock samples and sediments are used to characterize the geological setting of the vent field and composition of the hydrothermal deposits. The chimney walls are highly porous and lack defined chalcopyrite lined conduits, typical of high‐temperature chimneys. Overall, abundant Fe oxyhydroxide precipitation at high‐temperature vents at Fåvne reflects an excess of Fe over reduced S in the fluid, leading to precipitation of Fe oxide and oxyhydroxide minerals at high to moderate temperature vents (>100°C), and as microbially mediated and abiotic precipitation of Fe oxyhydroxide minerals at low‐temperature diffuse vents (<100°C). The mounds and chimneys exhibit low base metal and reduced S concentrations relative to globally averaged seafloor deposits and suggest subseafloor mixing of hydrothermal fluid with seawater, causing metal sulfide precipitation. Cobalt enrichment at Fåvne may reflect a subsurface influence of an ultramafic substrate on circulating fluids, although ultramafic rocks are absent on the seafloor and no other elements typical of ultramafic deposits are present.

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Gerd G. Kopper 60

Cited by 2 publications

References 0 publications

Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Hydroacoustic methodology for detection, localization, and quantification of gas bubbles rising from the seafloor at gas seeps from the eastern Black Sea

Iron Oxyhydroxide‐Rich Hydrothermal Deposits at the High‐Temperature Fåvne Vent Field, Mohns Ridge

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