scholarly journals Timing and origin of natural gas accumulation in the Siljan impact structure, Sweden

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Henrik Drake ◽  
Nick M. W. Roberts ◽  
Christine Heim ◽  
Martin J. Whitehouse ◽  
Sandra Siljeström ◽  
...  
Keyword(s):  
Microbial Activity ◽  
Source Rocks ◽  
Anaerobic Oxidation Of Methane ◽  
Isotopic Signatures ◽  
Gas Accumulation ◽  
Oxidation Of Methane ◽  
Cap Rock ◽  
A Minor ◽  
The Impact ◽  
Origin Of Natural Gas

Abstract Fractured rocks of impact craters may be suitable hosts for deep microbial communities on Earth and potentially other terrestrial planets, yet direct evidence remains elusive. Here, we present a study of the largest crater of Europe, the Devonian Siljan structure, showing that impact structures can be important unexplored hosts for long-term deep microbial activity. Secondary carbonate minerals dated to 80 ± 5 to 22 ± 3 million years, and thus postdating the impact by more than 300 million years, have isotopic signatures revealing both microbial methanogenesis and anaerobic oxidation of methane in the bedrock. Hydrocarbons mobilized from matured shale source rocks were utilized by subsurface microorganisms, leading to accumulation of microbial methane mixed with a thermogenic and possibly a minor abiotic gas fraction beneath a sedimentary cap rock at the crater rim. These new insights into crater hosted gas accumulation and microbial activity have implications for understanding the astrobiological consequences of impacts.

scholarly journals Miniaturized biosignature analysis reveals implications for the formation of cold seep carbonates at Hydrate Ridge (off Oregon, USA)

2007 ◽  
Vol 4 (6) ◽  
pp. 4443-4458 ◽  
Author(s):  
T. Leefmann ◽  
J. Bauermeister ◽  
A. Kronz ◽  
V. Liebetrau ◽  
J. Reitner ◽  
...  
Keyword(s):  
Microprobe Analysis ◽  
Cold Seep ◽  
Chemical Compositions ◽  
Anaerobic Oxidation Of Methane ◽  
Oxidation Of Methane ◽  
Hydrate Ridge ◽  
The Individual ◽  
A Minor ◽  
Relationship Of ◽  
The Relationship

Abstract. Methane-related carbonates from Hydrate Ridge typically show several macroscopically distinguishable phases, namely whitish aragonite, lucent aragonite, and gray micrite. The relationship of these phases to particular microorganisms or biogeochemical processes is as yet unclear. We used a miniaturized biomarker technique on mg samples, combined with factor analysis and subsequent electron microprobe analysis, to study lipid biomarkers and chemical compositions of the individual phases. This allows us to identify particular mechanisms involved in the formation of the different carbonate precipitates. Our combined analysis of biomarkers and petrographic traits shows that most of the lipids related to the anaerobic oxidation of methane (>90% by weight) are concentrated within only a minor compartment (~20% by volume) of the Hydrate Ridge carbonates (whitish aragonite). The patterns indicate that the whitish aragonite represents fossilized biofilms of methanotrophic consortia, whereas the precipitation of the lucent aragonite does not seem to be directly controlled by microorganisms. The gray micrite shows a partly Mg-calcitic mineralogy, higher pyrite contents, and a much higher proportion of allochthonous biomarkers. The formation of these precipitates is interpreted to reflect periodic methane-rich fluid pulses that disrupted the sediments and promoted the growth of the respective methanotrophic consortia along fluid pathways.

A novel 1D thermo-hydro-biogeochemical hydrate model to assess the full benthic environmental impact of methane gas hydrate dissociation

2021 ◽  
Author(s):  
Maria De La Fuente ◽  
Sandra Arndt ◽  
Tim Minshul ◽  
Héctor Marín-Moreno
Keyword(s):  
Environmental Impact ◽  
Gas Hydrate ◽  
Transport Processes ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Microbial Oxidation ◽  
Saturation State ◽  
Hydrate Dissociation ◽  
Oxidation Of Methane ◽  
The Impact

<p>Large quantities of methane (CH<sub>4</sub>) are stored in gas hydrates at shallow depths within marine sediments. These reservoirs are highly sensitive to ocean warming and if destabilized could lead to significant CH<sub>4</sub> release and global environmental impacts. However, the existence of such a positive feedback loop has recently been questioned as efficient CH<sub>4 </sub>sinks within the sediment-ocean continuum likely mitigate the impact of gas hydrate-derived CH<sub>4</sub> emissions on global climate. In particular, benthic anaerobic oxidation of methane (AOM) represents an important CH<sub>4 </sub>sink capable of completely consuming CH<sub>4</sub> fluxes before they reach the seafloor. However, the efficiency of this benthic biofilter is controlled by a complex interplay of multiphase methane transport and microbial oxidation processes and is thus highly variable (0-100%). In addition, AOM potentially enhances benthic alkalinity fluxes with important, yet largely overlooked implications for ocean pH, saturation state and CO<sub>2</sub> emissions. As a consequence, the full environmental impact of hydrate-derived CH<sub>4</sub> release to the ocean-atmosphere system and its feedbacks on global biogeochemical cycles and climate still remain poorly quantified. To the best our knowledge, currently available modelling tools to assess the benthic CH<sub>4</sub> sink and its environmental impact during hydrate dissociation do not account for the full complexity of the problem. Available codes generally do not explicitly resolve the dynamics of the microbial community and thus fail to represent transient changes in AOM biofilter efficiency and windows of opportunity for CH<sub>4</sub> escape. They also highly simplify the representation of  multiphase CH<sub>4 </sub>transport processes and gas hydrate dynamics and rarely assess the influence of hydrate-derived CH<sub>4</sub> fluxes on benthic-pelagic alkalinity and dissolved inorganic carbon fluxes. To overcome these limitations, we have developed a novel 1D thermo-hydro-biogeochemical hydrate model that improve the quantitative understanding of the benthic CH<sub>4</sub> sink and benthic carbon cycle-climate feedbacks in response to methane hydrate dissociation caused by temperature and sea-level perturbations. Our mathematical model builds on previous thermo-hydraulic hydrate simulators, expanding them to include the dominant microbial processes affecting CH<sub>4</sub> fluxes in a consistent and coupled mathematical formulation. The micro-biogeochemical reaction network accounts for the main redox reactions (i.e., aerobic degradation, organoclastic sulphate reduction (OSR), methanogenesis and aerobic-anaerobic oxidation of methane (AeOM-AOM)), carbonate dissolution/precipitation and equilibrium reactions that drive biogeochemical dynamics in marine hydrate-bearing sediments . In particular, the AOM rate is expressed as a bioenergetic rate law that explicitly accounts for biomass dynamics. Finally, the model allows tracking the carbon isotope signatures of all dissolved and solid carbon species. In this talk we will present the model structure for the multiphase-multicomponent hydrate system, describe the specific constitutive and reaction equations used in the formulation, discuss the numerical strategy implemented and illustrate the potential capabilities of the model.</p>

scholarly journals Coupled Dynamics of Iron and Phosphorus in Sediments of an Oligotrophic Coastal Basin and the Impact of Anaerobic Oxidation of Methane

PLoS ONE ◽  
2013 ◽  
Vol 8 (4) ◽  
pp. e62386 ◽  
Author(s):  
Caroline P. Slomp ◽  
Haydon P. Mort ◽  
Tom Jilbert ◽  
Daniel C. Reed ◽  
Bo G. Gustafsson ◽  
...  
Keyword(s):  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Coupled Dynamics ◽  
Oxidation Of Methane ◽  
The Impact ◽  
Coastal Basin

scholarly journals Anaerobic Oxidation of Methane in Freshwater Sediments of Rzeszów Reservoir

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 398
Author(s):  
Dorota Szal ◽  
Renata Gruca-Rokosz
Keyword(s):  
Electron Acceptors ◽  
Small Scale ◽  
Anaerobic Oxidation Of Methane ◽  
Sediment Layer ◽  
Anaerobic Oxidation ◽  
Freshwater Sediments ◽  
Oxidation Rates ◽  
Oxidation Of Methane ◽  
Dam Reservoirs ◽  
The Impact

The anaerobic oxidation of methane (AOM) is an important sink of methane that plays a significant role in global warming. However, evidence for the AOM in freshwater habitats is rare, especially in dam and weir (small-scale dam) reservoirs. Here, the AOM process was examined in freshwater sediments of a small-scale dam reservoir located in Rzeszów, SE Poland. The AOM rate was determined in the main experiment with the addition of the 13CH4 isotope marker (He+13CH4). Sediments were collected three times: in spring (in May, 15 °C), in summer (in July, 20 °C) and in autumn (in September, 10 °C). Further analysis considers the impact on AOM rate of potential electron acceptors present in pore-water (NO2−, NO3−, SO42−, and Fe3+ ions). The work suggests that an AOM process does take place in the studied reservoir sediments, with this evidenced by the presence in the headspace of an increased 13CO2 concentration deemed to derive from 13CH4 oxidation. Rates of AOM noted were of 0.36–1.42 nmol·g−1·h−1, with the most intensive oxidation in each sediment layer occurring at 20 °C. While none of the potential electron acceptors considered individually were found to have had a statistically significant influence on the AOM rate, their significance to the dynamics of the AOM process was not precluded.

scholarly journals Miniaturized biosignature analysis reveals implications for the formation of cold seep carbonates at Hydrate Ridge (off Oregon, USA)

2008 ◽  
Vol 5 (3) ◽  
pp. 731-738 ◽  
Author(s):  
T. Leefmann ◽  
J. Bauermeister ◽  
A. Kronz ◽  
V. Liebetrau ◽  
J. Reitner ◽  
...  
Keyword(s):  
Cold Seep ◽  
Chemical Compositions ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Sulfate Reducing ◽  
Oxidation Of Methane ◽  
Hydrate Ridge ◽  
Inorganic Matter ◽  
The Individual ◽  
A Minor

Abstract. Methane-related carbonates from Hydrate Ridge typically show several macroscopically distinguishable mineral phases, namely whitish aragonite, lucent aragonite, and gray micrite. The relationship of these phases to particular microorganisms or biogeochemical processes is as yet unclear. We used a miniaturized biomarker technique on mg samples, combined with factor analysis and subsequent electron microprobe analysis, to study lipid biomarkers and chemical compositions of the individual phases. This allows us to identify particular mechanisms involved in the formation of the different carbonate precipitates. Our combined analysis of biomarkers and petrographic traits shows that most of the lipids related to the anaerobic oxidation of methane (>90% by weight) are concentrated within only a minor compartment (~20% by volume) of the Hydrate Ridge carbonates, the whitish aragonite. The patterns indicate that the whitish aragonite represents fossilized biofilms of methanotrophic consortia containing mainly archaea of the ANME-2 group and sulfate reducing bacteria, whereas the precipitation of the lucent aragonite may have lacked the immediate proximity of microorganisms during formation. By contrast, the gray micrite formed by incorporation of allochthonous organic and inorganic matter during carbonate precipitation induced by the anaerobic oxidation of methane involving ANME-1 archaea.

scholarly journals Microbial activity and carbonate isotope signatures as a tool for identification of spatial differences in methane advection: a case study at the Pacific Costa Rican margin

2014 ◽  
Vol 11 (2) ◽  
pp. 507-523 ◽  
Author(s):  
S. Krause ◽  
P. Steeb ◽  
C. Hensen ◽  
V. Liebetrau ◽  
A. W. Dale ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Microbial Activity ◽  
Methane Flux ◽  
Anaerobic Oxidation Of Methane ◽  
Cold Seeps ◽  
Authigenic Carbonates ◽  
Biogenic Methane ◽  
Oxygen And Carbon Isotope ◽  
Oxidation Of Methane ◽  
Methane Fluxes

Abstract. The forearc of the convergent margin offshore Costa Rica is a region characterized by strong advection of methane-charged fluids causing the formation of ubiquitous cold seeps (mounds). Presented here are the first measurements of microbial anaerobic oxidation of methane (AOM) and sulfate reduction (SR) rates in sediments from two mounds (11 and 12), applying radiotracer techniques in combination with numerical modelling. In addition, analysis of microbial, methane-dependent carbonate δ18O, δ13C, and 87Sr / 86Sr signatures constrained the origin of the carbonate-precipitating fluid. Average rates of microbial activities differed by a factor of ~5 to 6 between Mound 11 (AOM 140.71 (±40.84 SD) mmol m−2 d−1, SR 117.25 (±82.06 SD) mmol m−2 d−1) and Mound 12 (AOM 22.37 (±0.85 SD) mmol m−2 d−1, SR 23.99 (±5.79 SD) mmol m−2 d−1). Modelling results yielded upward fluid advection velocities of 200 cm yr−1 at Mound 11 and 15 cm yr−1 at Mound 12. Analysis of oxygen and carbon isotope variations of authigenic carbonates from the two locations revealed more enriched values for Mound 11 (δ18O : 3.18 to 6.15‰; δ13C: −14.14 to −29.56‰) compared to Mound 12 (δ18O : 3.09 to 4.48‰; δ13C : −39.53 to −48.98‰). The variation of carbonate 87Sr / 86Sr indicated considerable admixture of deep-source fluid at Mound 11, while seawater 87Sr / 86Sr characteristics prevailed at Mound 12 during precipitation. The present study is in accordance with previous work supporting considerable differences of methane flux between the two mounds. It also strengthens the hypothesis of a dominant deep fluid source with thermogenic methane at Mound 11 versus a shallow source of biogenic methane at Mound 12. The results demonstrate that measurements of methane-driven microbial activity in combination with numerical modelling are a valid tool for constraining recent methane fluxes in the study area. In addition, the analysis of methane-derived authigenic carbonates provides an independent line of evidence for long-term fluid contribution to the porewater chemistry of shallow sediments in the study area.

scholarly journals Thermal Effects at Continent-Ocean Transform Margins: A 3D Perspective

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 193
Author(s):  
Daniel W. Schmid ◽  
Karthik Iyer ◽  
Ebbe H. Hartz
Keyword(s):  
Thermal Evolution ◽  
Numerical Models ◽  
Source Rocks ◽  
3D Fem ◽  
Boundary Segment ◽  
Continental Area ◽  
Transform Margin ◽  
Spreading Rates ◽  
A Minor ◽  
The Impact

Continental breakup along transform margins produces a sequence of (1) continent-continent, (2) continent-oceanic, (3) continent-ridge, and (4) continent-oceanic juxtapositions. Spreading ridges are the main sources of heat, which is then distributed by diffusion and advection. Previous work focused on the thermal evolution of transform margins built on 2D numerical models. Here we use a 3D FEM model to obtain the first order evolution of temperature, uplift/subsidence, and thermal maturity of potential source rocks. Snapshots for all four transform phases are provided by 2D sections across the margin. Our 3D approach yields thermal values that lie in between the previously established 2D end-member models. Additionally, the 3D model shows heat transfer into the continental lithosphere across the transform margin during the continental-continental transform stage ignored in previous studies. The largest values for all investigated quantities in the continental area are found along the transform segment between the two ridges, with the maximum values occurring near the transform-ridge corner of the trailing continental edge. This boundary segment records the maximum thermal effect up to 100 km distance from the transform. We also compare the impact of spreading rates on the thermal distribution within the lithosphere. The extent of the perturbation into the continental areas is reduced in the faster models due to the reduced exposure times. The overall pattern is similar and the maximum values next to the transform margin is essentially unchanged. Varying material properties in the upper crust of the continental areas has only a minor influence.

scholarly journals Modelling the impact of Siboglinids on the biogeochemistry of the Captain Arutyunov mud volcano (Gulf of Cadiz)

2012 ◽  
Vol 9 (6) ◽  
pp. 6683-6714
Author(s):  
K. Soetaert ◽  
D. van Oevelen ◽  
S. Sommer
Keyword(s):  
Transport Model ◽  
Sulfide Oxidation ◽  
Mud Volcano ◽  
Biogeochemical Model ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Oxidation Of Methane ◽  
Sediment Biogeochemistry ◽  
Reaction Transport ◽  
The Impact

Abstract. A 2-Dimensional mathematical reaction-transport model was developed to study the impact of the mud-dwelling frenulate tubeworm Siboglinum sp. on the biogeochemistry of a sediment (MUC15) at the Captain Arutyunov mud volcano (CAMV). By explicitly describing the worm in its surrounding sediment, we are able to make budgets of processes occurring in- or outside of the worm, and to quantify how different worm densities and biomasses affect the anaerobic oxidation of methane (AOM) and sulfide reoxidation (HSox). The model shows that, at the observed densities, the presence of a thin worm body is sufficient to keep the upper 10 cm of sediment well homogenized with respect to dissolved substances, in agreement with observations. By this "bio-ventilation" activity, the worm pushes the sulfate-methane transition (SMT) zone downward to the posterior end of its body, and simultaneously physically separates the sulfide produced during the anaerobic oxidation of methane from oxygen. While there is little scope for the AOM to take place in the tubeworm's body, 70% of the sulfide that is produced by sulfate reduction processes or that is advected in the sediment is preferentially shunted via the organism where it is oxidised by endosymbionts providing the energy for the worm's growth. The process of sulfide reoxidation, occurring predominantly in the worm's body is thus very distinct from the anaerobic oxidation of methane, which is a diffuse process that takes place in the sediments in the methane-sulfate transition zone. We show how the sulfide oxidation process is affected by increasing densities and length of the frenulates, and by upward advection velocity. Our biogeochemical model is one of the first to describe tubeworms explicitly. It can be used to directly link biological and biogeochemical observations at seep sites, and to study the impacts of mud-dwelling frenulates on the sediment biogeochemistry under varying environmental conditions. Also, it provides a tool to explore the competition between bacteria and fauna for available energy resources.

scholarly journals Variations in Archaeal and Bacterial Diversity Associated with the Sulfate-Methane Transition Zone in Continental Margin Sediments (Santa Barbara Basin, California)

2009 ◽  
Vol 75 (6) ◽  
pp. 1487-1499 ◽  
Author(s):  
Benjamin K. Harrison ◽  
Husen Zhang ◽  
Will Berelson ◽  
Victoria J. Orphan
Keyword(s):  
Microbial Diversity ◽  
Microbial Activity ◽  
Transition Zone ◽  
Gene Diversity ◽  
Anaerobic Oxidation Of Methane ◽  
Santa Barbara ◽  
Santa Barbara Basin ◽  
Sulfate Reducing ◽  
Oxidation Of Methane ◽  
Microbial Assemblage

ABSTRACT The sulfate-methane transition zone (SMTZ) is a widespread feature of continental margins, representing a diffusion-controlled interface where there is enhanced microbial activity. SMTZ microbial activity is commonly associated with the anaerobic oxidation of methane (AOM), which is carried out by syntrophic associations between sulfate-reducing bacteria and methane-oxidizing archaea. While our understanding of the microorganisms catalyzing AOM has advanced, the diversity and ecological role of the greater microbial assemblage associated with the SMTZ have not been well characterized. In this study, the microbial diversity above, within, and beneath the Santa Barbara Basin SMTZ was described. ANME-1-related archaeal phylotypes appear to be the primary methane oxidizers in the Santa Barbara Basin SMTZ, which was independently supported by exclusive recovery of related methyl coenzyme M reductase genes (mcrA). Sulfate-reducing Deltaproteobacteria phylotypes affiliated with the Desulfobacterales and Desulfosarcina-Desulfococcus clades were also enriched in the SMTZ, as confirmed by analysis of dissimilatory sulfite reductase (dsr) gene diversity. Statistical methods demonstrated that there was a close relationship between the microbial assemblages recovered from the two horizons associated with the geochemically defined SMTZ, which could be distinguished from microbial diversity recovered from the sulfate-replete overlying horizons and methane-rich sediment beneath the transition zone. Comparison of the Santa Barbara Basin SMTZ microbial assemblage to microbial assemblages of methane seeps and other organic matter-rich sedimentary environments suggests that bacterial groups not typically associated with AOM, such as Planctomycetes and candidate division JS1, are additionally enriched within the SMTZ and may represent a common bacterial signature of many SMTZ environments worldwide.

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