Evidence of polygenetic carbon trapping in the Oman Ophiolite: Petro-structural, geochemical, and carbon and oxygen isotope study of the Wadi Dima harzburgite-hosted carbonates (Wadi Tayin massif, Sultanate of Oman)

Noël, Julie; Godard, Marguerite; Oliot, Émilien; Martínez, Isabelle; Williams, Morgan; Boudier, Françoise; Rodriguez, O.; Chaduteau, Carine; Escario, S.; Gouze, Philippe

doi:10.1016/j.lithos.2018.08.020

Cited by 35 publications

(51 citation statements)

References 85 publications

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“…In the Oman ophiolite, for example, H 2 -rich gases have the same exit points as alkaline spring waters, which are located along fault and shear zones (Neal and Stanger, 1983). In such a case, water and gases react immediately with the atmosphere resulting in carbonate deposits such as in Oman (Noel et al, 2018) and in New Caledonia (Deville and Prinzhofer, 2016). In case of water accumulation (river or lake), H 2 being poorly soluble in water at low pressure (Lopez-Lazaro et al, 2019 and reference therein), continuous degassing can be observed in the form of bubbles.…”

Section: H 2 Transfer In Subsurfacementioning

confidence: 99%

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Myagkiy

Moretti

Brunet

2020

BSGF - Earth Sci. Bull.

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Natural H2 emissions from the ground have now been measured in many places worldwide. These emissions can be localized on faults or be more diffuse in some sedimentary basins, usually of Proterozoic age. In such a case, emanation zones are often visible from aerial images or on high-resolution topographic maps since they correspond to slight depressions of circular to elliptic shape. Furthermore, the rounded depressions are covered with a scrubby vegetation which often contrasts with the surrounding vegetation. Although the emission structure displays a very regular shape, the distribution of H2 concentration in the first meter of soil in such a structure does show a clear pattern. For example, the maximum concentration is almost never measured in the center of the structure and the few time-resolved data show that the soil H2 concentration is variable with time. Here, the time and space evolution of H2 concentration is simulated using a 2-D advective-diffusive model of H2 transport in porous media. Several parameters have been tested as the depth and periodicity of the H2 point source (pulsed), bacterial H2 consumption and permeability heterogeneities of the soil. The radius of the structure is linked to the time spent by the H2 in the soil that depends on the soil permeability, the depth of the gas leakage point and the pressure of the bubble. To account for field observations, the case of a shaly, less permeable, heterogeneity in the center of the structures has been modeled. It resulted in an increase of the concentration toward the rim of the structure and a close to zero signal in its center. If the deep signal is periodic with a frequency smaller than a few hours, H2 concentration within the soil is almost constant; in other cases, the near surface concentration wave reflects the concentration periodicity of the source with a delay (in the range of 12 h for 30 m of soil) and so the near surface H2 concentration values will be highly dependent on the time at which the measurement is performed. H2 monitoring through a sensor network is thus mandatory to characterize the H2 dynamics in the soil of fairy circles.

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Section: H 2 Transfer In Subsurfacementioning

confidence: 99%

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Myagkiy

Moretti

Brunet

2020

BSGF - Earth Sci. Bull.

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“…Extensive outcrops of weathered peridotites show different forms and degrees of CO 2 mineralization based on local geological contexts i.e. on small scale variations in the chemistry and hydrodynamic rock properties: carbonates may form large chimneys in deep-sea hydrothermal sites (e.g., Ludwig et al, 2006), travertine deposits from springs in peridotite catchments (Kelemen and Matter, 2008), but also geometrical veins through partially hydrated (Noël et al, 2018) to fully carbonated peridotites, such as ophicalcite (Bernoulli and Weissert, 1985;Schwarzenbach et al, 2013) and listvenite (Hansen et al, 2005;Nasir et al, 2007).…”

Section: Olivine (Fo 90 ) Mg-carbonates Quartzmentioning

confidence: 99%

“…Carbonation of mafic and ultramafic rocks (mainly basalts and peridotites) is a widespread process in nature for example, in the past and present oceanic crust and mantle exposed on the seafloor (e.g., Nakamura and Kato, 2004;Ludwig et al, 2006) and within ophiolites (Matter and Kelemen, 2009;Noël et al, 2018). It occurs through the interaction of carbon dioxide (CO ) with divalent metal ions (Mg 2+ , Fe 2+ , Ca 2+ ) contained in mafic silicates (e.g., olivine) to precipitate solid carbonate minerals and quartz (e.g., Oelkers et al, 2008):…”

Section: Introductionmentioning

confidence: 99%

Control of CO2 on flow and reaction paths in olivine-dominated basements: An experimental study

Peuble

Godard

Gouze

et al. 2019

Geochimica et Cosmochimica Acta

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The objective of this paper is to quantify the mass transfers involved in the hydrothermal alteration of olivine-rich peridotites in the presence of CO 2-enriched waters, and to determine their effects on the rock hydrodynamic properties. Three flow-through experiments were performed at a temperature of 185 °C and a total pressure of 22.5 ± 2.5 MPa. They consisted in injecting a hydrothermal fluid with different concentrations of carbon dioxide (CO 2 = 6.26, 62.6 and 659.7 mmol.L-1 i.e. pCO 2 = 0.1, 1 and 10 MPa, respectively) into cylinders of sintered San Carlos (Arizona, USA) olivine grains. The results show that for low pCO 2 conditions (from 0.1 to 1 MPa), olivine is mainly altered into hematite and Mg(Fe)-rich phyllosilicates. Such iddingsitic-type assemblages may clog most of the rock flow paths, resulting in a strong decrease in permeability. Rare CaFe -carbonate minerals also precipitated under these conditions despite the initial Mg-rich system. For higher pCO 2 conditions (~10 MPa), olivine is more efficiently altered. A greater amount of poorly crystallized Fe(Mg)-rich phyllosilicates and magnesite is produced, and the carbonation rate of olivine is 3 to 11 times higher than when the pCO 2 is 10 to 100 times lower. Interestingly, the changes in porosity caused by the formation of carbonated and hydrous minerals are small while a strong decrease in permeability is measured during the experiments. The formation of reduced carbon is also observed. It is located preferentially at the inlet, where pH is the lowest. This testifies to a competition between reduction (probably associated with the oxidation of ferrous iron) and carbonation; two processes involved in the fixation of CO 2 in a mineral form. One may speculate that the formation of reduced carbon can also be a significant mechanism of CO 2 sequestration in olivine-dominated basements.

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“…The mantle section of the Samail ophiolite shows evidence of at least three distinct hydrothermal events that occurred over a wide range of conditions and are likely to be recorded in the same sample (e.g., Noël et al . 2018). In situ measurement of oxygen isotopes in serpentine minerals has therefore the potential to unravel (i) the relative contribution of these episodes of water/rock interaction to the formation of serpentine, (ii) the physical and chemical conditions that favour low‐ T serpentinisation and (iii) the coupling between hydration and carbonation of peridotite in ophiolitic terrains.…”

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confidence: 99%

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

Scicchitano

Spicuzza

Ellison

et al. 2020

Geostandard Geoanalytic Res

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The ability to constrain the petrogenesis of multiple serpentine generations recorded at the microscale is crucial for estimating the extent and conditions of modern versus fossil serpentinisation in ophiolites. To address matrix bias effects during oxygen isotope analysis by SIMS, we present the first investigation analysing antigorite in the compositional range Mg# = 77.5–99.5 mole %, using a CAMECA IMS‐1280 secondary ion mass spectrometer. Spot‐to‐spot homogeneity is ≤ 0.5‰ (2s) for the new antigorite reference materials. The relative bias between antigorite reference materials with different Mg/Fe ratios is described by a second‐order polynomial, and a maximum difference in bias of ~ 1.8‰ was measured for Mg# ~ 78 to 100. We observed a bias up to ~ 1.0‰ between lizardite and antigorite attributed to their different crystal structures. Orientation effects up to ~ 1‰ were observed in chrysotile. The new analytical protocol allowed the identification of oxygen isotope zoning up to ~ 7‰ in serpentine minerals from two serpentinites recovered from an area of active serpentinisation in the Samail ophiolite. Thus, in situ analysis is capable of resolving isotopic heterogeneity that may directly reflect changes in the physical and chemical conditions of multiple serpentinisation events in the Samail ophiolite.

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Evidence of polygenetic carbon trapping in the Oman Ophiolite: Petro-structural, geochemical, and carbon and oxygen isotope study of the Wadi Dima harzburgite-hosted carbonates (Wadi Tayin massif, Sultanate of Oman)

Cited by 35 publications

References 85 publications

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Control of CO2 on flow and reaction paths in olivine-dominated basements: An experimental study

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

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Evidence of polygenetic carbon trapping in the Oman Ophiolite: Petro-structural, geochemical, and carbon and oxygen isotope study of the Wadi Dima harzburgite-hosted carbonates (Wadi Tayin massif, Sultanate of Oman)

Cited by 35 publications

References 85 publications

Space and time distribution of subsurface H2concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Space and time distribution of subsurface H2concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Control of CO2 on flow and reaction paths in olivine-dominated basements: An experimental study

In Situ Oxygen Isotope Determination in Serpentine Minerals by SIMS: Addressing Matrix Effects and Providing New Insights on Serpentinisation at Hole BA1B (Samail ophiolite, Oman)

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Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model

Space and time distribution of subsurface H₂concentration in so-called “fairy circles”: Insight from a conceptual 2-D transport model