Active methane venting observed at giant pockmarks along the U.S. mid-Atlantic shelf break

Newman, K. R.; Cormier, Marie-Hélène; Weissel, Jeffrey K.; Driscoll, Neal W.; Kastner, Miriam; Solomon, E. A.; Robertson, Gretchen; Hill, J. C.; Singh, Hanumant; Camilli, Richard; Eustice, Ryan M.

doi:10.1016/j.epsl.2007.11.053

Cited by 61 publications

(54 citation statements)

References 46 publications

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“…Modern seep activity can be detected through seabed observations, pore water analysis, methane anomaly detection, and many other methods (Borowski et al, 1996(Borowski et al, , 1999Borowski, 2004;Newman et al, 2008;Bayon et al, 2009bBayon et al, , 2011Mazumdar et al, 2012aMazumdar et al, , 2014Brothers et al, 2013Brothers et al, , 2014Lemaitre et al, 2014;Skarke et al, 2014), but temporal variations in methane flux in the past are not well constrained because it is difficult to select the appropriate indicators in quantifying and age determining the occurrence of seep activity. Consequently, little is known about the impact of methane seepage on the surrounding sediment environment in seep settings.…”

Section: Introductionmentioning

confidence: 99%

Using sediment geochemistry to infer temporal variation of methane flux at a cold seep in the South China Sea

Niu

Dong

Chen

et al. 2016

Marine and Petroleum Geology

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Section: Introductionmentioning

confidence: 99%

Using sediment geochemistry to infer temporal variation of methane flux at a cold seep in the South China Sea

Niu

Dong

Chen

et al. 2016

Marine and Petroleum Geology

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“…Any seep may be composed of a single gas stream or several ones very close to each other such that they clearly define its perimeter. Submarine seeps, at cold seeps, occur worldwide along the continental margins and are usually related to geological structures with either positive reliefs such as submarine pingoes [1][2][3][4][5][6][7], carbonate concretions and pavements [8][9][10][11], and mud volcanoes [9,[12][13][14][15][16][17][18] or negative reliefs like pockmarks [13,[19][20][21][22][23]. They also occur in seafloor-reaching fault areas at tectonically active regions without being associated with a specific relief [24][25][26][27][28].…”

Section: Introductionmentioning

confidence: 99%

Gas Seepage along the Edge of the Aquitaine Shelf (France): Origin and Local Fluxes

et al. 2017

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During the scientific expedition GAZCOGNE2 at the Bay of Biscay nine gas seeps were sampled for the first time and their flux was measured using an in situ pressure-preservation sampler (PEGAZ, © IFREMER). Overall, three sites were investigated to determine the nature and the origin of the gases bubbling at the seafloor and forming acoustic plumes into the water column, as this was the question raised from the first geologic study of the area. This has guided our study and accordingly corresponds to the main purpose of the present article. Thus, the molecular and isotopic ( D and 13 C) analyses revealed that the gas seeps were primarily composed of methane. Both methane and ethane are of microbial origin, and the former has been generated by microbial reduction of carbon dioxide. Heavier hydrocarbons accounted for less than 0.06% mol of the total amount. Despite the microbial origin of methane, the samples exhibit subtle differences with respect to the 13 C CH 4 values, which varied between −72.7 and −66.1‰. It has been suggested that such a discrepancy was predominantly governed by the occurrence of anaerobic methane oxidation. The PEGAZ sampler also enabled us to estimate the local gas fluxes from the sampled streams. The resulting values are extremely heterogeneous between seeps, ranging from 35 to 368 mLn⋅min −1 . Assuming a steady discharge, the mean calculated methane emission for the nine seeps is of 38 kmol⋅yr −1 . Considering the extent of the seep area, this very local estimate suggests that the Aquitaine Shelf is a very appropriate place to study methane discharge and its fate on continental shelves.

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“…La filtración de gas de los sedimentos suele ser muy localizada y sería difícil de detectar mediante el muestreo de estaciones fijas en la columna de agua. Sondeos ultrasónicos (e.g., Canet et al 2010) y/o el uso de vehículos submarinos autónomos o remolcados con sensores de metano CTD y METS (e.g., Merewether et al 1985, Newman et al 2008) serían medios más eficaces para detectar el metano y las plumas hidrotermales en una región amplia como el norte del GC, y serían útiles para ubicar las filtraciones individuales, incluyendo la filtración inferida en el umbral de CB.…”

Section: Discusión Y Conclusionesunclassified

“…Gas seepage from the sediments is likely to be highly localized and would be difficult to detect by fixed station water column sampling. Underway echo sounding (e.g., Canet et al 2010) and/or deploying a towed or autonomous underwater vehicle with CTD and METS methane sensors (e.g., Merewether et al 1985, Newman et al 2008 would be a more efficient means of detecting methane and hydrothermal plumes over a wide area, such as the NGC, and would be helpful in pinpointing the locations of individual seeps, including the inferred seep near the BC sill. que han perforado el fondo marino muy cerca de nuestras estaciones 5 y 7 (Persaud et al 2003).…”

Section: Discusión Y Conclusionesmentioning

confidence: 99%

Dissolved methane in the sills region of the Gulf of California

et al. 2013

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ABSTRACT. An unusual combination of features makes the Midriff Islands region of the northern Gulf of California (NGC) a strong atmospheric methane source. Oceanographic isolation by a series of sills and islands along with upward transport of nutrient-rich water enhanced by tidal currents, upwelling, and overflows results in high productivity. The resulting high phytoplankton biomass likely stimulates biogeochemical cycling that, in turn, may stimulate biological methane production in the water column and sediments. Additionally, venting of abiogenic methane-rich hydrothermal fluids in this tectonically active area and seepage of biogenic or thermogenic methane gas from the sediments may also be important sources. We found elevated methane concentrations throughout our study area, the highest within the Ballenas Channel, which was supersaturated with respect to atmospheric methane at all depths. Our vertical methane profiles show that elevated dissolved methane concentrations in the NGC are mainly associated with Gulf of California Water (GCW). Data from 22 stations suggest southward advection of methane via the methane-rich GCW, and lower methane concentrations south of the sills area. Our observations of supersaturated methane concentrations at all stations and all depths in the Ballenas Channel suggest that it is a strong source of methane to the atmosphere and to other parts of the NGC. In particular, station 7 at 50, 20, and 0 m depths had methane (CH 4 . These values are higher than those measured at many other high productivity sites worldwide including upwelling sites, and suggest input of methane via hydrothermal fluids or seepage from the sediments.Key words: dissolved methane, gas chromatography, potential methane sources and origin.RESUMEN. Una combinación inusual de rasgos oceanográficos hacen de la región de las grandes islas del norte del golfo de California (NGC) una importante fuente de metano hacia la atmósfera. El aislamiento oceanográfico por umbrales e islas y el transporte vertical de agua rica en nutrientes, aumentado por mareas, surgencias y desbordes, resultan en alta productividad. La alta biomasa fitoplanctónica probablemente estimula el reciclado biogeoquímico, que a su vez estimula la producción biológica de metano en el agua y sedimento. Adicionalmente, el venteo de fluidos hidrotermales ricos en metano en esta zona tectónicamente activa y las filtraciones de gas metano, termogénico o biogénico, del sedimento también pueden ser fuentes importantes. Se encontraron concentraciones elevadas de metano a lo largo del área de estudio, principalmente dentro del canal de Ballenas, con supersaturación respecto al metano atmosférico en todas las profundidades. Nuestros perfiles verticales de metano muestran que las elevadas concentraciones de metano en el NGC están asociadas al Agua del Golfo de California (AGC). Datos de 22 estaciones sugieren una advección de metano al sur vía AGC rica en metano, y concentraciones menores de metano al sur de los umbrales. La supersaturación en el canal d...

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Active methane venting observed at giant pockmarks along the U.S. mid-Atlantic shelf break

Cited by 61 publications

References 46 publications

Using sediment geochemistry to infer temporal variation of methane flux at a cold seep in the South China Sea

Using sediment geochemistry to infer temporal variation of methane flux at a cold seep in the South China Sea

Gas Seepage along the Edge of the Aquitaine Shelf (France): Origin and Local Fluxes

Dissolved methane in the sills region of the Gulf of California

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