Fluid and chemical fluxes in and out of sediments hosting methane hydrate deposits on Hydrate Ridge, OR, I: Hydrological provinces

Torres, Marta E; McManus, James; Hammond, Douglas E.; Angelis, Marie A. de; Heeschen, Katja; Colbert, Steven L.; Tryon, M. D.; Brown, Kevin M.; Suess, Erwin

doi:10.1016/s0012-821x(02)00733-1

Cited by 280 publications

(248 citation statements)

References 30 publications

Supporting

Mentioning

228

Contrasting

Unclassified

Order By: Relevance

“…Vigorous streams of gas bubbles have been observed emanating from the seafloor, and the average gas flux from southern Hydrate Ridge is estimated to be ~1.9 kg m 2 yr 1 [11,27,28]. Based on the measured water flux and the occurrence of benthic communities in this area, Torres et al [19] identified three distinct active fluid provinces: the gas discharge sites, bacterial mat sites, and clam sites (Figure 1(a), 2). The gas discharge sites are discrete seep points with average diameter of 1 cm.…”

Section: Geological Setting At Southern Hydrate Ridgementioning

confidence: 99%

“…Methane gas and pore water emanate rapidly from the seafloor with an average flux of 5800 kg m 2 yr 1 (1 kg m 2 yr 1 =171 mmol m 2 d 1 ) and 10 10 kg m 2 yr 1 (1 kg m 2 yr 1 =0.1 cm yr 1 ), respectively [19]. Dense bacterial mats cover the bacterial mat sites and a lower fluid flux of 0.18-0.53 kg m 2 yr 1 for methane gas and 100-2500 kg m 2 yr 1 for pore water [18,19] exist at these sites. Clams cover the seafloor at the clam sites with weakest fluid flow at these sites.…”

Section: Geological Setting At Southern Hydrate Ridgementioning

confidence: 99%

“…Clams cover the seafloor at the clam sites with weakest fluid flow at these sites. The methane gas flux is < 0.006 kg m 2 yr 1 and the pore water flux is 100-20 kg m 2 yr 1 [18,19], indicating that seawater could flow intermittently into the sediment.…”

Section: Geological Setting At Southern Hydrate Ridgementioning

confidence: 99%

“…sites [3,[18][19][20]. The water flux measured at the Bush Hill cold vent is 5-7000 kg m 2 yr 1 ("" represents down flow) [21] and 100-4000 kg m 2 yr 1 at Hydrate Ridge [19].…”

mentioning

confidence: 99%

“…The water flux measured at the Bush Hill cold vent is 5-7000 kg m 2 yr 1 ("" represents down flow) [21] and 100-4000 kg m 2 yr 1 at Hydrate Ridge [19]. The upward movement of the fluid from the deep high temperature to shallow low temperature zone could increase subsurface temperatures, and in turn inhibit the formation of gas hydrate [22,23].…”

mentioning

confidence: 99%

See 4 more Smart Citations

Influence of water flow on gas hydrate accumulation at cold vents

Cao

Zheng

Chen

2013

Sci. China Earth Sci.

View full text Add to dashboard Cite

A cold vent is an area where methane-rich fluid seepage occurs. This seepage may alter the local temperature, salinity, and subsequent accumulation of the gas hydrate. Using a kinetic gas hydrate formation model and in situ measurement of temperature, salinity and fluid flux at the southern summit of Hydrate Ridge, we simulate the gas hydrate accumulation at three distinct fluid sites: clam, bacterial mat, and gas discharge sites. At the clam sites (pore water flux < 20 kg m 2 yr 1 ), pore water advection has little influence on temperature and salinity. However, the salinity and temperature are increased (peak salinity > 0.8 mol kg 1 ) by the formation of gas hydrate causing the base of the hydrate stability zone to move gradually from ~115 to ~70 meters below seafloor (mbsf). The gas hydrate saturation at the clam sites is relatively high. The water flux at the bacterial mat sites ranges from 100 to 2500 kg m 2 yr 1 . The water flow suppresses the increase in salinity resulting in a salinity close to or slightly higher than that of seawater (< 0.65 mol kg 1 ). Heat advection by water flow increases temperature significantly, shifting the base of the hydrate stability zone to above 50 or even 3 mbsf. The gas hydrate saturation is relatively low at the bacterial mat site. At the gas discharge sites, the pore water flux could reach 10 10 kg m 2 yr 1 , and the temperature could reach that of the source area in 9 min. There is no gas hydrate formation at the gas discharge sites. Our simulative analysis therefore reveals that a lower pore water flux would result in lower salinity, higher temperature, and a shallower base of the hydrate stability zone. This in turn induces a lower gas hydrate formation rate, lower hydrate saturation, and eventually less gas hydrate resources.cold vent, fluid seepage, temperature, salinity, gas hydrate, numerical simulation Citation:

show abstract

Section: Geological Setting At Southern Hydrate Ridgementioning

confidence: 99%

Section: Geological Setting At Southern Hydrate Ridgementioning

confidence: 99%

Section: Geological Setting At Southern Hydrate Ridgementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Influence of water flow on gas hydrate accumulation at cold vents

Cao

Zheng

Chen

2013

Sci. China Earth Sci.

View full text Add to dashboard Cite

show abstract

Character of seismic motion at a location of a gas hydrate‐bearing mud volcano on the SW Barents Sea margin

et al. 2014

View full text Add to dashboard Cite

The Håkon Mosby mud volcano (HMMV) at 1270 m water depth on the SW Barents Sea slope has been intensively studied since its discovery in 1989. A variety of sensors monitored morphological, hydrological, geochemical, and biological parameters in the HMMV area. An ocean bottom seismometer deployment allowed us to register seismic motion for 2 years, from October 2008 to October 2010. The analysis of seismic records documents two types of seismic signals. The first type are harmonic tremors with frequency peaks around 4-5 and 8-10 Hz that occur in swarms. Their origin could be from fluid flow circulation or resonant vibrations of gas bubbles or from delayed movement of fluid-rich sediments in the conduit or in a deeper pseudo-mud chamber of the HMMV. Because swarms occur with a periodicity of~6 h, tide-related effects are suspected to influence the mechanism originating the tremors. The second type of signals are regional earthquakes that were in 15 cases recognized in seismic records. The activity of harmonic tremors was not significantly affected by earthquakes.

show abstract

Time‐series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

Philip

Denny

Solomon

et al. 2016

Geochem Geophys Geosyst

View full text Add to dashboard Cite

An estimated 500–2500 gigatons of methane carbon is sequestered in gas hydrate at continental margins and some of these deposits are associated with overlying methane seeps. To constrain the impact that seeps have on methane concentrations in overlying ocean waters and to characterize the bubble plumes that transport methane vertically into the ocean, water samples and time‐series acoustic images were collected above Southern Hydrate Ridge (SHR), a well‐studied hydrate‐bearing seep site ∼90 km west of Newport, Oregon. These data were coregistered with robotic vehicle observations to determine the origin of the seeps, the plume rise heights above the seafloor, and the temporal variability in bubble emissions. Results show that the locations of seep activity and bubble release remained unchanged over the 3 year time‐series investigation, however, the magnitude of gas release was highly variable on hourly time scales. Bubble plumes were detected to depths of 320–620 m below sea level (mbsl), in several cases exceeding the upper limit of hydrate stability by ∼190 m. For the first time, sustained gas release was imaged at the Pinnacle site and in‐between the Pinnacle and the Summit area of venting, indicating that the subseafloor transport of fluid and gas is not restricted to the Summit at SHR, requiring a revision of fluid‐flow models. Dissolved methane concentrations above background levels from 100 to 300 mbsl are consistent with long‐term seep gas transport into the upper water column, which may lead to the build‐up of seep‐derived carbon in regional subsurface waters and to increases in associated biological activity.

show abstract

Fluid and chemical fluxes in and out of sediments hosting methane hydrate deposits on Hydrate Ridge, OR, I: Hydrological provinces

Cited by 280 publications

References 30 publications

Influence of water flow on gas hydrate accumulation at cold vents

Influence of water flow on gas hydrate accumulation at cold vents

Character of seismic motion at a location of a gas hydrate‐bearing mud volcano on the SW Barents Sea margin

Time‐series measurements of bubble plume variability and water column methane distribution above Southern Hydrate Ridge, Oregon

Contact Info

Product

Resources

About