Distribution of free gas in marine sediments: a global overview

Fleischer, Peter; Orsi, Thomas H.; Richardson, Michael D.; Anderson, A.

doi:10.1007/s003670100072

Cited by 206 publications

(27 citation statements)

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“…Methane in marine sediments can either be dissolved in pore waters or-in a case where in situ saturation is exceeded-exist as a free gas (Fleischer et al, 2001). The saturation level is controlled by pressure, temperature, and salinity (Yamamoto et al, 1976).…”

Section: Results and Discussion Methane In The Sedimentmentioning

confidence: 99%

Source, Origin, and Spatial Distribution of Shallow Sediment Methane in the Chukchi Sea

Matveeva¹,

Savvichev²,

Семенова³

et al. 2015

Oceanog

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Section: Results and Discussion Methane In The Sedimentmentioning

confidence: 99%

Source, Origin, and Spatial Distribution of Shallow Sediment Methane in the Chukchi Sea

Matveeva¹,

Savvichev²,

Семенова³

et al. 2015

Oceanog

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“…Gas bearing sediments occur worldwide (e.g., Emeis et al 2004, Laier and Jensen 2007, Mazumdar et al 2009, Chun et al 2012, typically in shallow environments with a depth of less than 50 m (Fleischer et al 2001). As derived from low-temperature chemical and biochemical processes at or near the sea-floor, methane (CH4) is the most common and abundant hydrocarbon gas in near-surface sediments from offshore areas (Judd et al 2002).…”

Section: Introductionmentioning

confidence: 99%

High-Resolution Seismic Characterization of Shallow Gas Accumulations in the Southern Shelf of Marmara Sea, Turkey

Vardar

Alpar

2016

Acta Geophys.

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A b s t r a c tHigh-resolution seismic survey was conducted to investigate acoustic characteristics of gassy sediments along the southern shelf of the Sea of Marmara. The acoustic turbidity zones outlined within the study area are generally below 2-9 m (2-10 ms TWT) the seafloor whilst this vertical distance varies between 9 and 21 m (10-25 ms TWT) for acoustic blanket type reflections. The gassy sediments cover an area of sea floor of about 45, 110, and 75 km 2 in front of Gönen River, Kocasu River, and Gemlik Bay, respectively. The gassy sediments in the center of Gemlik Bay exhibited an elliptical geometry similar to its basin while the others have deltaic forms in front of the rivers. The sea bottom and near surface sedimentary units are made-up of organic-rich sediments, mostly transported by the southern rivers. The gas observed in sediments is thought to be of biogenic origin, which may be caused by degradation of organic matter in the sediment.

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“…Constrained to fine-grained substrates and typically associated with subsurface gas (Judd and Hovland, 2007), the factors that determine why pockmarks scar some gassy seafloors while other muddy embayments remain relatively flat are unknown. In eastern North America pockmark fields are not reported south of Long Island Sound (Fleisher et al, 2001;Poppe et al, 2006), despite the abundance of well-studied, gassy, muddy estuaries (e.g., Reeburgh, 1969;Schubel, 1974;Hagen and Vogt, 1998;Martens et al, 1998). The absence of pockmarks south of the glacial terminus suggests that local and regional heterogeneities, possibly related to glacial or sea-level history or bedrock geology, influence pockmark field distribution (e.g., Rogers et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Shallow stratigraphic control on pockmark distribution in north temperate estuaries

et al. 2012

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Pockmark fields occur throughout northern North American temperate estuaries despite the absence of extensive thermogenic hydrocarbon deposits typically associated with pockmarks. In such settings, the origins of the gas and triggering mechanism(s) responsible for pockmark formation are not obvious. Nor is it known why pockmarks proliferate in this region but do not occur south of the glacial terminus in eastern North America. This paper tests two hypotheses addressing these knowledge gaps: 1) the region's unique sea-level history provided a terrestrial deposit that sourced the gas responsible for pockmark formation; and 2) the region's physiography controls pockmarks distribution. This study integrates over 2500 km of high-resolution swath bathymetry, Chirp seismic reflection profiles and vibracore data acquired in three estuarine pockmark fields in the Gulf of Maine and Bay of Fundy. Vibracores sampled a hydric paleosol lacking the organic-rich upper horizons, indicating that an organic-rich terrestrial deposit was eroded prior to pockmark formation. This observation suggests that the gas, which is presumably responsible for the formation of the pockmarks, originated in Holocene estuarine sediments (loss on ignition 3.5-10%), not terrestrial deposits that were subsequently drowned and buried by mud. The 7470 pockmarks identified in this study are non-randomly clustered. Pockmark size and distribution relate to Holocene sediment thickness (r 2 =0.60), basin morphology and glacial deposits. The irregular underlying topography that dictates Holocene sediment thickness may ultimately play a more important role in temperate estuarine pockmark distribution than drowned terrestrial deposits. These results give insight into the conditions necessary for pockmark formation in nearshore coastal environments.Published by Elsevier B.V.

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Distribution of free gas in marine sediments: a global overview

Cited by 206 publications

References 0 publications

Source, Origin, and Spatial Distribution of Shallow Sediment Methane in the Chukchi Sea

Source, Origin, and Spatial Distribution of Shallow Sediment Methane in the Chukchi Sea

High-Resolution Seismic Characterization of Shallow Gas Accumulations in the Southern Shelf of Marmara Sea, Turkey

Shallow stratigraphic control on pockmark distribution in north temperate estuaries

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