Methane occurrences in the Canadian Shield

Sherwood, Betty; Fritz, P.; Frape, Shaun K.; Macko, Stephen A.; Weise, Stephan M.; Welhan, J. A.

doi:10.1016/0009-2541(88)90117-9

Cited by 63 publications

(23 citation statements)

References 26 publications

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“…α o/w for other low temperature (<100°C) microbial/abiogenic LMW n-alkanes from crystalline rock aquifers in the Witwatersrand Basin, S. Africa (WARD et al, 2004;LIN et al, 2006;ONSTOTT et al, 2006;SHERWOOD LOLLAR et al, 2008) andFennoscandian Shield (NURMI et al, 1988;SHERWOOD LOLLAR et al, 1993a,b) are also much lower than equilibrium predictions at the temperatures likely experienced by these systems. As previously suggested by SHERWOOD et al (1988) and SHERWOOD LOLLAR et al (1993b), the most likely explanation for the extremely negative δ 2 H values of these hydrocarbons is that they formed by abiogenic or microbial reductive processes (likely at low temperatures) involving extremely 2 H-depleted H 2(aq) (δ 2 H H2 values as low as -695‰) that is present in these systems (SHERWOOD et al, 1988;SHERWOOD LOLLAR et al, 1993b;LIN et al, 2006). Though some isotopic exchange cannot be discounted, the apparent lack of isotopic equilibrium between water and alkane H in these gases is reasonable given that the alkane-alkene mechanism may not be able to effectively promote H exchange in C 2+ hydrocarbons at the low temperatures of the these systems (~35-60°C, SHERWOOD LOLLAR et al, 2008).…”

Section: H / 1 H Ratios and Abiogenesis In Igneous Environmentssupporting

confidence: 65%

“…The abiogenic formation of aliphatic hydrocarbons during hydrothermal alteration of ultramafic crust has been extensively discussed SHERWOOD et al, 1988;PROSKUROWSKI et al, 2006;KONN et al, 2009). Though the exact mechanism for production of n-alkanes in highly-reducing crustal fluids is uncertain, it is assumed to be analogous to the industrial Fischer-Tropsch reaction and involves both reduction of inorganic carbon (CO 2 or CO) to methyl/methylene moieties and subsequent polymerization on a catalytic mineral surface (see review in .…”

Section: H / 1 H Ratios and Abiogenesis In Igneous Environmentsmentioning

confidence: 99%

“…GLEIN et al, 2008;GLEIN et al, 2009;MUMMA et al, 2009). Methane production has long been associated with serpentinization of ultramafic rock SHERWOOD et al, 1988;CHARLOU and DONVAL, 1993;CHARLOU et al, 1998;KELLEY et al, 2001; and the origin of methane in black smoker fluids has been the subject of considerable discussion ever since seafloor hydrothermal activity was first discovered in 1977 KELLEY and FRUH-GREEN, 1999;. In the absence of a thermogenic (i.e.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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This thesis presents the results of four discrete investigations into processes governing the organic and inorganic chemical composition of seafloor hydrothermal fluids in a variety of geologic settings. Though Chapters 2 through 5 of this thesis are disparate in focus, each represents a novel investigation aimed at furthering our understanding of subsurface geochemical processes affecting hydrothermal fluid compositions. Chapters 2 and 3 concern the abiotic (nonbiological) formation of organic compounds in high temperature vent fluids, a process which has direct implications for the emergence of life in early Earth settings and sustainment of present day microbial populations in hydrothermal environments. Chapter 2 represents an experimental investigation of methane (CH 4 ) formation under hydrothermal conditions. The overall reduction of carbon dioxide (CO 2 ) to CH 4 , previously assumed to be kinetically inhibited in the absence of mineral catalysts, is shown to proceed on timescales pertinent to crustal residence times of hydrothermal fluids. In Chapter 3, the abundance of methanethiol (CH 3 SH), considered to be a crucial precursor for the emergence of primitive chemoautotrophic life, is characterized in vent fluids from ultramafic-, basalt-and sediment-hosted hydrothermal systems. Previous assumptions that CH 3 SH forms by reduction of CO 2 are not supported by the observed distribution in natural systems. Chapter 4 investigates factors regulating the hydrogen isotope composition of hydrocarbons under hydrothermal conditions. Isotopic exchange between low molecular weight n-alkanes and water is shown to be facilitated by metastable equilibrium reactions between alkanes and their corresponding alkenes, which are feasible in natural systems. In Chapter 5, the controls on vent fluid composition in a backarc hydrothermal system are investigated. A comprehensive survey of the inorganic geochemistry of fluids from sites of hydrothermal activity in the eastern Manus Basin indicates that fluids there are influenced by input of acidic magmatic solutions at depth, and subsequently modified by variable extents of seawater entrainment and mixing-related secondary acidity production. CHAPTER 1 IntroductionSeafloor hydrothermal systems associated with the generation of oceanic crust represent a dramatic expression of heat and mass transfer from the interior of the Earth. In addition to profound effects on ocean chemistry, convective circulation of seawater through volcanically active oceanic crust leads to the formation of metal sulfide deposits. In addition, seafloor hot springs are often invoked as ideal settings from which early microbial life could have emerged.Since the initial discovery of low temperature venting at the Galápagos Spreading Center in 1977 (CORLISS et al., 1979), our understanding of the composition and diversity of hydrothermal solutions has expanded greatly. During convection through oceanic crust of basaltic composition, O 2 -replete seawater reacts with crustal rock, typically producin...

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Section: H / 1 H Ratios and Abiogenesis In Igneous Environmentssupporting

confidence: 65%

Section: H / 1 H Ratios and Abiogenesis In Igneous Environmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Reeves¹

2010

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“…Areas where intrusions have evidence of hydrogen gas generation are at Sudbury Mine, Ontario, Canada (Sherwood et al 1988), which produced 96 litres per day of hydrogen (= 3.4 cfd, in normally quoted hydrocarbon test figures) and Juuka Mine, Finland (Sherwood Lollar et al 1993).…”

Section: Large Layered Crustal Intrusionsmentioning

confidence: 99%

Hydrogen exploration: a review of global hydrogen accumulations and implications for prospective areas in NW Europe

Smith

Shepherd

Styles

et al. 2005

PGC

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From a geological perspective, hydrogen has been neglected. It is not as common as biogenic or thermogenic methane, which are ubiquitous in hydrocarbon basins, or carbon dioxide, which is common in geologically-active areas of the world. Nevertheless, small flows of hydrogen naturally reach the Earth's surface, occur in some metal mines and emerge beneath the oceans in a number of places worldwide. These occurrences of hydrogen are associated with abiogenic and biogenic methane, Further research should aim to identify the extent of the hydrogen flux and its probable dominant role in the abiogenic production of hydrocarbons in Precambrian times, a natural process now largely replaced by biogenic participation. A similar industrial process replicates serpentinization, producing hydrogen and ultimately liquid hydrocarbons on a commercial scale in some countries. It remains to be proved whether a contribution from exploration can be made to any future Hydrogen Economy.

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“…In subsurface mines in the Canadian Shield, exploration boreholes intersecting extensive fracture networks release waters rich in reduced gases (H 2 , CH 4 , C 2+ ) and noble gases, which exsolve upon depressurization. Sampling and characterization of fracture fluids from Kidd Creek have been described in previous studies (Sherwood et al, 1988;Sherwood Lollar et al, 2002;Sherwood Lollar et al, 2007;Sherwood Lollar et al, 2008;Holland et al, 2013). We analyzed methane sampled from boreholes at the 7850 ′ -and 9500 ′ -levels (Table 2.1).…”

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confidence: 99%

The geochemistry of methane isotopologues

Wang¹

2017

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This thesis documents the origin, distribution, and fate of methane and several of its isotopic forms on Earth. Using observational, experimental, and theoretical approaches, I illustrate how the relative abundances of 12 CH 4 , 13 CH 4 , 12 CH 3 D, and 13 CH 3 D record the formation, transport, and breakdown of methane in selected settings.Chapter 2 reports precise determinations of 13 CH 3 D, a "clumped" isotopologue of methane, in samples collected from various settings representing many of the major sources and reservoirs of methane on Earth. The results show that the information encoded by the abundance of 13 CH 3 D enables differentiation of methane generated by microbial, thermogenic, and abiogenic processes. A strong correlation between clumped-and hydrogen-isotope signatures in microbial methane is identified and quantitatively linked to the availability of H 2 and the reversibility of microbially-mediated methanogenesis in the environment. Determination of 13 CH 3 D in combination with hydrogen-isotope ratios of methane and water provides a sensitive indicator of the extent of C-H bond equilibration, enables fingerprinting of methane-generating mechanisms, and in some cases, supplies direct constraints for locating the waters from which migrated gases were sourced. Chapter 3 applies this concept to constrain the origin of methane in hydrothermal fluids from sediment-poor vent fields hosted in mafic and ultramafic rocks on slow-and ultraslow-spreading mid-ocean ridges. The data support a hypogene model whereby methane forms abiotically within plutonic rocks of the oceanic crust at temperatures above ca. 300• C during respeciation of magmatic volatiles, and is subsequently extracted during active, convective hydrothermal circulation. Chapter 4 presents the results of culture experiments in which methane is oxidized in the presence of O 2 by the bacterium Methylococcus capsulatus strain Bath. The results show that the clumped isotopologue abundances of partially-oxidized methane can be predicted from knowledge of 13 C/ 12 C and D/H isotope fractionation factors alone.: Shuhei Ono, Ph.D. Acknowledgments I fear that this section will not do justice to the people I have not the space to thank individually. Alas, here goes. To those whose names are not specifically listed here, thank you too. I wish first to thank Shuhei Ono. The work this thesis represents could not have happened without his bold vision and the license to explore and question that working in his lab afforded. His unbridled optimism, breadth of scientific curiosity, personal integrity, and accessibility to his personnel are traits I one day hope to emulate. I thank him for his nonjudgmental yet appropriately measured support of many of my ideas-even those that led nowhere-, for believing in me even when I found it difficult to do so myself, and for teaching me to change pump oil, build vacuum lines, and drink Icelandic vodka.I also wish to thank my thesis committee members Jeff Seewald, Roger Summons, and John Pohlman, for their in...

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Methane occurrences in the Canadian Shield

Cited by 63 publications

References 26 publications

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Laboratory and field-based investigations of subsurface geochemical processes in seafloor hydrothermal systems

Hydrogen exploration: a review of global hydrogen accumulations and implications for prospective areas in NW Europe

The geochemistry of methane isotopologues

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