OCEANIC METHANE HYDRATE: THE CHARACTER OF THE BLAKE RIDGE HYDRATE STABILITY ZONE AND THE POTENTIAL FOR METHANE EXTRACTION

Marine sediments of the Blake Ridge province exhibit clearly defined geophysical indications for the presence of gas hydrates and a free gas phase. Despite being one of the world’s best-studied gas hydrate provinces and having been drilled during Ocean Drilling Program (ODP) Leg 164, discrepancies between previous model predictions and reported chemical profiles as well as hydrate concentrations result in uncertainty regarding methane sources and a possible co-existence between hydrates and free gas near the base of the gas hydrate stability zone (GHSZ). Here, by using a new multi-phase finite element (FE) numerical model, we investigate different scenarios of gas hydrate formation from both single and mixed methane sources (in-situ biogenic formation and a deep methane flux). Moreover, we explore the evolution of the GHSZ base for the past 10 Myr using reconstructed sedimentation rates and non-steady-state P-T solutions. We conclude that (1) the present-day base of the GHSZ predicted by our model is located at the depth of ~450 mbsf, thereby resolving a previously reported inconsistency between the location of the BSR at ODP Site 997 and the theoretical base of the GHSZ in the Blake Ridge region, (2) a single in-situ methane source results in a good fit between the simulated and measured geochemical profiles including the anaerobic oxidation of methane (AOM) zone, and (3) previously suggested 4 vol.%–7 vol.% gas hydrate concentrations would require a deep methane flux of ~170 mM (corresponds to the mass of methane flux of 1.6 × 10−11 kg s−1 m−2) in addition to methane generated in-situ by organic carbon (POC) degradation at the cost of deteriorating the fit between observed and modelled geochemical profiles.

Download Full-text

Pore size controls on the base of the methane hydrate stability zone in the Kumano Basin, offshore Japan

Geophysical Research Letters ◽

10.1002/2014gl062135 ◽

2014 ◽

Vol 41 (22) ◽

pp. 8021-8028 ◽

Cited By ~ 6

Author(s):

Hugh Daigle ◽

Brandon Dugan

Keyword(s):

Pore Size ◽

Methane Hydrate ◽

Stability Zone ◽

Kumano Basin ◽

Hydrate Stability

Download Full-text

Interface instability of methane hydrate stability zone in permafrost deposits

Theoretical and Computational Fluid Dynamics ◽

10.1007/s00162-012-0277-7 ◽

2012 ◽

Vol 27 (5) ◽

pp. 637-650 ◽

Cited By ~ 3

Author(s):

Ekaterina Kolchanova ◽

Tatyana Lyubimova ◽

Dmitry Lyubimov ◽

Oleg Zikanov

Keyword(s):

Methane Hydrate ◽

Stability Zone ◽

Interface Instability ◽

Hydrate Stability

Download Full-text

Climatically driven instability of marine methane hydrate along a canyon-incised continental margin

Geology ◽

10.1130/g48638.1 ◽

2021 ◽

Author(s):

Richard J. Davies ◽

Miguel Ángel Morales Maqueda ◽

Ang Li ◽

Mark Ireland

Keyword(s):

Methane Hydrate ◽

Ocean Warming ◽

Stability Field ◽

Continental Margins ◽

Stability Zone ◽

Show Evidence ◽

Past Climate Change ◽

The Stability ◽

The Impact ◽

Hydrate Stability

Establishing how past climate change affected the stability of marine methane hydrate is important for our understanding of the impact of a future warmer world. As oceans shallow toward continental margins, the base of the hydrate stability zone also shallows, and this delineates the feather edge of marine methane hydrate. It is in these rarely documented settings that the base of the hydrate stability zone intersects the seabed and hydrate can crop out where it is close to being unstable and most susceptible to dissociation due to ocean warming. We show evidence for a seismically defined outcrop zone intersecting canyons on a canyon-incised margin offshore of Mauritania. We propose that climatic, and hence ocean, warming since the Last Glacial Maximum as well as lateral canyon migration, cutting, and filling caused multiple shifts of the hydrate stability field, and therefore hydrate instability and likely methane release into the ocean. This is particularly significant because the outcrop zone is longer on canyon-incised margins than on less bathymetrically complex submarine slopes. We propose considerably more hydrate will dissociate in these settings during future ocean warming, releasing methane into the world’s oceans.

Download Full-text

Adaptations ofAtribacteriato life in methane hydrates: hot traits for cold life

10.1101/536078 ◽

2019 ◽

Cited By ~ 4

Author(s):

Jennifer B. Glass ◽

Piyush Ranjan ◽

Cecilia B. Kretz ◽

Brook L. Nunn ◽

Abigail M. Johnson ◽

...

Keyword(s):

Carboxylic Acids ◽

Gas Hydrate ◽

Methane Hydrate ◽

Inositol Phosphate ◽

Hyperthermophilic Archaea ◽

Rrna Gene ◽

Stability Zone ◽

Cold Temperatures ◽

Hydrate Bearing Sediments ◽

Hydrate Stability

SummaryGas hydrates harbor gigatons of natural gas, yet their microbiomes remain mysterious. We bioprospected methane hydrate-bearing sediments from under Hydrate Ridge (offshore Oregon, USA, ODP Site 1244) using 16S rRNA gene amplicon, metagenomic, and metaproteomic analysis.Atribacteria(JS-1 Genus 1) sequences rose in abundance with increasing sediment depth. We characterized the most complete JS-1 Genus 1 metagenome-assembled genomic bin (B2) from the deepest sample, 69 meters below the seafloor (E10-H5), within the gas hydrate stability zone. B2 harbors functions not previously reported forAtribacteria, including a primitive respiratory complex and myriad capabilities to survive extreme conditions (e.g. high salt brines, high pressure, and cold temperatures). SeveralAtribacteriatraits, such as a hydrogenase-Na+/H+antiporter supercomplex (Hun) and di-myo-inositol-phosphate (DIP) synthesis, were similar to those from hyperthermophilic archaea. ExpressedAtribacteriaproteins were involved in transport of branched chain amino acids and carboxylic acids. Transporter genes were downstream from a novel helix-turn-helix transcriptional regulator, AtiR, which was not present inAtribacteriafrom other sites. Overall,Atribacteriaappear to be endowed with unique strategies that may contribute to its dominance in methane-hydrate bearing sediments. Active microbial transport of amino and carboxylic acids in the gas hydrate stability zone may influence gas hydrate stability.Originality-Significance StatementThis work provides insights into the metabolism and adaptations of elusiveAtribacteria(JS-1 clade) that are ubiquitous and abundant in methane-rich ecosystems. We show that JS-1 (Genus 1) from methane hydrate stability zones contain metabolisms and stress survival strategies similar to hyperthermophilic archaea.

Download Full-text

INFLUENCE OF SALT DIFFUSION ON THE STABILITY OF METHANE GAS HYDRATE IN THE ARCTIC SHELF

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2020-4-1-91-97 ◽

2020 ◽

Vol 4 (1) ◽

pp. 91-97

Author(s):

Valentina V. Malakhova

Keyword(s):

Bottom Sediments ◽

Methane Hydrate ◽

Arctic Shelf ◽

The Arctic ◽

Stability Zone ◽

Hydrate Dissociation ◽

Dissociation Temperature ◽

The Stability ◽

Salt Diffusion ◽

Hydrate Stability

Suitable conditions for the formation of methane hydrates exist in the bottom sediments of shallow Arctic shelves in the presence of permafrost. Salt diffusion into hydrated bottom sediments can help accelerate hydrate degradation. An analysis of the influence of salinity of the bottom sediments of the Arctic shelf on the thickness of the methane hydrate stability zone was based on mathematical modeling. Estimates of the thickness of the stability zone were obtained in experiments with various correlations which relate the hydrate dissociation temperature in the presence of aqueous solutions containing salts.

Download Full-text