Crack geometry of serpentinized peridotites inferred from onboard ultrasonic data from the Oman Drilling Project

Katayama, Ikuo; Abe, Natsue; Okazaki, Keishi; Hatakeyama, Kenichi; Akamatsu, Yuya; Michibayashi, Katsuyoshi; Godard, Marguerite; Kelemen, P. B.

doi:10.1016/j.tecto.2021.228978

Cited by 8 publications

(9 citation statements)

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“…Based on a variety of different lines of reasoning, catchment-scale-, Hole-to-Hole scale-, single Hole scaleand core-sample scale-studies have found that permeability in peridotite hosted aquifers in the Samail ophiolite is >10 −14 m 2 near the surface, and ∼10 −14 to 10 −15 below ∼100 m, with considerable Hole to Hole variability in the depth of this transition within the MBO (Dewandel et al, 2004(Dewandel et al, , 2005Katayama et al, 2020Katayama et al, , 2021Lods et al, 2020).…”

Section: Past Studies Of Groundwater Composition and Hydrology In The...mentioning

confidence: 99%

“…Studies addressing this issue via study of low temperature peridotite weathering in the Samail ophiolite includes Kelemen and Hirth (2012), Malvoisin et al (2020), andYoshida et al (2020). More generally, fracture-related frequency, porosity, and permeability in serpentinized peridotites has been studied in OmanDP drill core samples by Katayama et al (2020Katayama et al ( , 2021.…”

Section: Post-emplacement Alteration Of the Mbo And Vicinitymentioning

confidence: 99%

“…More generally, fracture‐related frequency, porosity, and permeability in serpentinized peridotites has been studied in OmanDP drill core samples by Katayama et al. (2020, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Initial Results From the Oman Drilling Project Multi‐Borehole Observatory: Petrogenesis and Ongoing Alteration of Mantle Peridotite in the Weathering Horizon

et al. 2021

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The Oman Drilling Project “Multi‐Borehole Observatory” (MBO) samples an area of active weathering of tectonically exposed peridotite. This article reviews the geology of the MBO region, summarizes recent research, and provides new data constraining ongoing alteration. Host rocks are partially to completely serpentinized, residual mantle harzburgites, and replacive. Dunites show evidence for “reactive fractionation,” in which cooling, crystallizing magmas reacted with older residues of melting. Harzburgites and dunites are 65%–100% hydrated. Ferric to total iron ratios vary from 50% to 90%. In Hole BA1B, alteration extent decreases with depth. Gradients in water and core composition are correlated. Serpentine veins are intergrown with, and cut, carbonate veins with measurable 14C. Ongoing hydration is accompanied by SiO2 addition. Sulfur enrichment in Hole BA1B may result from oxidative leaching of sulfur from the upper 30 m, coupled with sulfate reduction and sulfide precipitation at 30–150 m. Oxygen fugacity deep in Holes BA3A, NSHQ14, and BA2A is fixed by the reaction 2H2O = 2H2 + O2 combined with oxidation of ferrous iron in serpentine, brucite, and olivine. fO2 deep in Holes BA1A, BA1D, and BA4A is 3–4 log units above the H2O‐H2 limit, controlled by equilibria involving serpentine and brucite. Variations in alteration are correlated with texture, with reduced, low SiO2 assemblages in mesh cores recording very low water/rock ratios, juxtaposed with adjacent veins recording much higher ratios. The proportion of reduced mesh cores versus oxidized veins increases with depth, and the difference in fO2 recorded in cores and veins decreases with depth.

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Section: Past Studies Of Groundwater Composition and Hydrology In The...mentioning

confidence: 99%

Section: Post-emplacement Alteration Of the Mbo And Vicinitymentioning

confidence: 99%

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Initial Results From the Oman Drilling Project Multi‐Borehole Observatory: Petrogenesis and Ongoing Alteration of Mantle Peridotite in the Weathering Horizon

et al. 2021

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“…The serpentinization and carbonation processes can lead to the development of cracks due to reaction‐induced dilation, which can affect the seismic velocity of the mantle. Although this effect depends on the crack shape, serpentinites contain cracks with relatively large aspect ratios, which have little effect on the seismic velocity (e.g., Hatakeyama & Katayama, 2020; Katayama et al, 2021).…”

Section: Seismic Velocity During Mantle Hydration and Carbonationmentioning

confidence: 99%

Role of mantle carbonation in trench outer‐rise region in the global carbon cycle

Katayama,

Okazaki,

Okamoto

2023

Island Arc

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A nearly balanced carbon budget between subduction input and degassing output has likely controlled the long‐term surface environment and habitability of Earth throughout geological history. However, the ongoing extensive hydration and carbonation of the mantle in trench outer‐rise regions may affect the global carbon budget. In this study, we show that the carbon content of the lithospheric mantle can be inferred from geophysical data and thermodynamic modeling. Based on the seismic velocity anomaly in trench outer‐rise regions, we estimated that the total carbon flux due to mantle carbonation is 7–31 Mt C/year, with possible fluid‐to‐rock mass ratios of 250–1000. These values are similar to the carbon uptake by altered oceanic crust, indicating that mantle carbonation has a significant effect on the subduction carbon budget. Although there are large uncertainties on the estimates of the subduction and degassing carbon fluxes, secular cooling of the mantle leads to the development of outer‐rise faults associated with bending of the oceanic lithosphere and increased mantle carbonation, which may disrupt the self‐regulating system of the global carbon cycle on geological timescales.

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“…The recovered cores were systematically described and analyzed onboard in the laboratory of drilling vessel Chikyu , with preliminary data, including fundamental physical properties, having been reported recently (Kelemen, Matter, Teagle, Coggon, & the Oman Drilling Project Science Team, 2020). Recent studies have investigated the roles of pore space in the oceanic lithosphere using physical property data obtained onboard, such as electrical resistivity and elastic wave velocity (Katayama et al., 2020, 2021). However, although P‐wave velocity (

{V}_{\mathrm{P}}

) passing through the core samples was obtained during the shipboard measurements, S‐wave velocity (

{V}_{\mathrm{S}}

) was not measured because of the lack of a measurement system, despite the fact that a combination of P‐ and S‐wave velocities can give information about crack geometry and fluid contribution.…”

Section: Introductionmentioning

confidence: 99%

Cross‐Property Relationship Between Electrical Resistivity and Elastic Wave Velocity of Crustal Rocks From the Oman Drilling Project Hole GT3A: Implications for in Situ Geophysical Properties of Oceanic Crust

et al. 2023

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Geophysical properties of oceanic crust are strongly influenced by the presence of cracks. We studied the effects of cracks on the physical properties of oceanic crustal rocks collected from the ICDP Oman Drilling Project Hole GT3A. Electrical resistivity and P‐ and S‐wave velocities were measured under dry and brine‐water‐saturated conditions for each sample. The experimental results reveal that electrical resistivity and elastic wave velocities are differently correlated with porosity. We performed joint inversion of the measured electrical and elastic properties combining an effective medium model by Kachanov and a statistical crack fluid flow model by Guéguen and Dienes with percolation theory. As a result, the variations in electrical and elastic properties can be related to the crack microstructural parameters: crack density and aspect ratio, as well as connectivity of cracks evaluated from crack density. To understand the influence of in situ conditions of oceanic crust, the joint inversion using the proposed cross‐property relationship was performed for geophysical properties obtained by logging measurements at IODP Hole 1256D. Results show the depth variations of resistivity and sonic velocities can be successfully interpreted by decreasing crack porosity and connectivity. Our data and analysis can provide new insights into the interpretation of geophysical data from the oceanic crust at which pore‐fluid plays key roles in various geodynamic activities.

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Crack geometry of serpentinized peridotites inferred from onboard ultrasonic data from the Oman Drilling Project

Cited by 8 publications

References 51 publications

Initial Results From the Oman Drilling Project Multi‐Borehole Observatory: Petrogenesis and Ongoing Alteration of Mantle Peridotite in the Weathering Horizon

Initial Results From the Oman Drilling Project Multi‐Borehole Observatory: Petrogenesis and Ongoing Alteration of Mantle Peridotite in the Weathering Horizon

Role of mantle carbonation in trench outer‐rise region in the global carbon cycle

Cross‐Property Relationship Between Electrical Resistivity and Elastic Wave Velocity of Crustal Rocks From the Oman Drilling Project Hole GT3A: Implications for in Situ Geophysical Properties of Oceanic Crust

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