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L.A. Barnard

Bio: L.A. Barnard is an academic researcher. The author has contributed to research in topics: Ridge (meteorology). The author has an hindex of 1, co-authored 1 publications receiving 94 citations.

Papers
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Book ChapterDOI
01 Nov 1983
TL;DR: A recent DSDP Leg 11 report indicated the presence of gas hydrates in sediments of the Blake Outer Ridge as mentioned in this paper, and Leg 76 coring and sampling confirms that they are present there.
Abstract: Natural gas hydrates are clathrates in which water molecules form a crystalline framework that includes and is stabilized by natural gas (mainly methane) at appropriate conditions of high pressures and low temperatures. The conditions for the formation of gas hydrates are met within continental margin sediments below water depths greater than about 500 m where the supply of methane is sufficient to stabilize the gas hydrate. Observations on DSDP Leg 11 suggested the presence of gas hydrates in sediments of the Blake Outer Ridge. Leg 76 coring and sampling confirms that, indeed, gas hydrates are present there. Geochemical evidence for gas hydrates in sediment of the Blake Outer Ridge includes (1) high concentrations of methane, (2) a sediment sample with thin, matlike layers of white crystals that released a volume of gas twenty times greater than its volume of pore fluid, (3) a molecular distribution of hydrocarbon gases that excluded hydrocarbons larger than isobutane, (4) results from pressure core barrel experiments, and (5) pore-fluid chemistry. The molecular composition of the hydrocarbons in these gas hydrates and the isotopic composition of the methane indicate that the gas is derived mainly from microbiological processes operating on the organic matter within the sediment. Although gas hydrates apparently are widespread on the Blake Outer Ridge, they probably are not of great economic significance as a potential, unconventional, energy resource or as an impermeable cap for trapping upwardly migrating gas at Site 533.

94 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors discuss three important aspects of gas hydrates: their potential as a fossil fuel resource, their role as a submarine geohazard, and their effects on global climate change.
Abstract: Gas hydrates are naturally ocurring solids consisting of water molecules forming a lattice of cages, most of which contain a molecule of natural gas, usually methane. The present article discusses three important aspects of gas hydrates: their potential as a fossil fuel resource, their role as a submarine geohazard, and their effects on global climate change. 70 refs., 16 figs., 1 tab.

1,364 citations

Journal ArticleDOI
TL;DR: The estimated amount of organic carbon in the methane-hydrate reservoir greatly exceeds that in many other reservoirs of the global carbon cycle as discussed by the authors, such as the atmosphere (3.6 Gt), terrestrial biota (830 Gt); terrestrial soil, detritus and peat (1960 Gt).

1,074 citations

Journal ArticleDOI
TL;DR: The largest accumulations on Earth of natural gas are in the form of gas hydrate, found mainly offshore in outer continental margin sediment and, to a lesser extent, in polar regions commonly associated with permafrost as mentioned in this paper.

404 citations

Journal ArticleDOI
TL;DR: In this article, the authors test a hypothesis relating large pore water sulfate gradients to upward methane flux and the presence of underlying methane gas hydrate on continental rises by examining: (1) Pore water geochemical data available from the global data set of Deep Sea Drilling Project-Ocean Drilling Program (DSDP-ODP) sites; (2) sulfate data from 51 coring sites located at the Carolina Rise and Blake Ridge (offshore southeastern United States); and (3) the relationship between the distribution of bottom-simulating reflectors (BS

355 citations

Journal ArticleDOI
TL;DR: The total amount of methane in gas hydrates probably exceeds 1019 g of methane carbon as mentioned in this paper, which may enhance global warming and be a contributing factor in global climate change.
Abstract: Abstract Natural gas hydrates occur world-wide in polar regions, usually associated with onshore and offshore permafrost, and in sediment of outer continental and insular margins. The total amount of methane in gas hydrates probably exceeds 1019 g of methane carbon. Three aspects of gas hydrates are important: their fossil fuel resource potential; their role as a submarine geohazard; and their effects on global climate change. Because gas hydrates represent a large amount of methane within 2000 m of the Earth’s surface, they are considered to be an unconventional, unproven source of fossil fuel. Because gas hydrates are metastable, changes of pressure and temperature affect their stability. Destabilized gas hydrates beneath the sea floor lead to geological hazards such as submarine slumps and slides, examples of which are found world-wide. Destabilized gas hydrates may also affect climate through the release of methane, a ‘greenhouse’ gas, which may enhance global warming and be a factor in global climate change.

341 citations