Fluid rock interactions on residual mantle peridotites overlain by shallow oceanic limestones: Insights from Wadi Fins, Sultanate of Oman

Obeso, Juan Carlos de; Kelemen, P. B.

doi:10.1016/j.chemgeo.2018.09.022

Cited by 47 publications

(96 citation statements)

References 76 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The clumped isotope temperatures complement earlier thermometry work in the Samail ophiolite that described relatively low formation temperatures (clumped isotope temperatures between 23–43 °C) for young carbonate veins in peridotite forming during present‐day weathering (Streit et al, 2012), slightly higher temperatures for calcite veins in peridotite beneath a Cretaceous unconformity (25–60 °C, de Obeso & Kelemen, 2018), and yet higher temperatures for carbonate from outcrop samples of listvenite and the metamorphic sole within a few kilometers of Hole BT1B (listvenite 61–114 °C, n = 15; metamorphic sole 64–171 °C, n = 4) (Falk & Kelemen, 2015). Also, Falk and Kelemen (2015) documented the presence of intergrown quartz and antigorite, with and without talc and magnesite, in several samples from a gradational contact between listvenite and serpentinite about 2 km north of Hole BT1B.…”

Section: Discussionsupporting

confidence: 84%

Ultramafic Rock Carbonation: Constraints From Listvenite Core BT1B, Oman Drilling Project

et al. 2020

View full text Add to dashboard Cite

The occurrence of the quartz-carbonate alteration assemblage (listvenite) in ophiolites indicates that ultramafic rock represents an effective sink for dissolved CO 2. However, the majority of earlier studies of ultramafic rock carbonation had to rely on the surface exposure of reaction textures and field relationships. Here we present the first observations on ultramafic rock alteration obtained from the 300 m deep BT1B drill hole, ICDP Oman Drilling Project, allowing for a continuous and high-resolution investigation. Hole BT1B recovered continuous drill core intersecting surface alluvium, 200 m of altered ultramafic rock comprising mainly listvenite and minor serpentinite bands at 90 and 180 m depth, and 100 m of the underlying metamorphic sole. Textural evidence suggests that the carbonation of fully serpentinized harzburgite commenced by non-equilibrium growth of spheroidal carbonate characterized by sectorial zoning resulting from radially oriented low-angle boundaries. In the serpentinite, carbonate spheroids are composed of alternating magnesite cores and dolomite rims, whereas texturally similar carbonate in the listvenite is composed of Fe-rich magnesite cores and CaFe rich magnesite rims. The distinct compositions and mineral inclusions indicate that the carbonation extent was controlled by fluid accessibility resulting in the simultaneous formation of limited carbonate in the serpentinite bands and complete carbonation in the listvenite parts of BT1B. The presence of euhedral magnesite overgrowing spheroidal carbonate in the listvenite suggests near-equilibrium conditions during the final stage of carbonation. The carbonate clumped isotope thermometry constrains carbonate crystallization between 50°C and 250°C, implying repeated infiltration of reactive fluids during ophiolite uplift and cooling.

show abstract

Section: Discussionsupporting

confidence: 84%

Ultramafic Rock Carbonation: Constraints From Listvenite Core BT1B, Oman Drilling Project

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Veins of carbonate ± serpentine are a striking feature of the outcrops (figure 2). These are similar to the veins described by de Obeso & Kelemen [30], from outcrops a few hundred metres east (downstream) from the sample locality described in this paper. The wider carbonate veins (approx.…”

Section: (D) Carbonate and Serpentine Veinssupporting

confidence: 89%

“…[22][23][24]), together with 5-15% dunite [25][26][27], and refertilized lherzolites near the basal thrust [28]. These peridotites are pervasively serpentinized, with serpentine (± brucite) composing approximately 30 wt% in 'fresh' rock to nearly 100% [29,30]. The alteration occurred throughout the history of the ophiolite, beginning near the axis of the oceanic spreading ridges where the Samail ophiolite crust formed (e.g.…”

Section: Geological Settingmentioning

confidence: 99%

“…Using the petrological and mineralogical constraints described above, we used a modified version of the de Obeso & Kelemen [30] EQ3/6 model [46] of hydrous fluids reacting with peridotite. The model is run at 50 MPa and 60°C, the maximum alteration temperature estimated for Wadi Fins based on clumped isotope data [30]. In addition to major oxides, we included Ni, S and Cu in the model system.…”

Section: Thermodynamic Modelling (A) Model Set-upmentioning

confidence: 99%

See 1 more Smart Citation

Major element mobility during serpentinization, oxidation and weathering of mantle peridotite at low temperatures

Obeso

Kelemen

2020

Phil. Trans. R. Soc. A.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In section the model was further explored by adding a nonadvective flux term representing the diffusion of water in cracks (driven by gradients in chemical potentials), which leads to a dramatic increase in the maximum extent and areal distribution of reaction, and the formation of multiple generations of cracks. The continued development of this feedback could eventually reproduce the orthogonal crack textures that are often seen in peridotite outcrops (see e.g., de Obeso and Kelemen, ; Iyer et al, ; Kelemen et al, ).…”

Section: Discussionmentioning

confidence: 96%

Phase‐Field Modeling of Reaction‐Driven Cracking: Determining Conditions for Extensive Olivine Serpentinization

2020

Self Cite

View full text Add to dashboard Cite

The motion of plates leads to cycling of chemically bound water and volatiles through the Earth's interior, having consequences for arc magmatism and seismic activity at subduction zones. Tectonically exhumed peridotite at the Earth's surface provides a substantial sink for water and carbon. The natural chemical disequilibrium that exists between exposed mantle peridotite and the surface waters/atmosphere could potentially be harnessed as a negative carbon emission technology. Understanding this process is therefore critical from both a petrological and environmental perspective. Retrograde metamorphism is physically complex, potentially involving an interplay between positive (cracking) and negative (clogging) feedbacks that may limit, or promote, fluid supply to unreacted minerals. Modeling studies are important in helping to constrain the conditions that control the extent of reaction in ultramafic rocks. This study builds on a previously reported model that describes olivine hydration/carbonation in a poroelastic medium, coupling fluid flow, elastic deformation, and mass transfer between chemically active phases. Here we extend this model to include brittle failure, which is crucial given the widely held hypothesis that reaction-driven cracking is the dominant positive feedback in these processes. Here we explore the use of phase-field methods to simulate brittle failure in a poroelastic medium, in the context of hydration (serpentinization) of peridotite. We show that reaction-driven cracking in this model can generate a positive feedback that, under certain conditions, can lead to 100% transformation of olivine to serpentine.

show abstract

Fluid rock interactions on residual mantle peridotites overlain by shallow oceanic limestones: Insights from Wadi Fins, Sultanate of Oman

Cited by 47 publications

References 76 publications

Ultramafic Rock Carbonation: Constraints From Listvenite Core BT1B, Oman Drilling Project

Ultramafic Rock Carbonation: Constraints From Listvenite Core BT1B, Oman Drilling Project

Major element mobility during serpentinization, oxidation and weathering of mantle peridotite at low temperatures

Phase‐Field Modeling of Reaction‐Driven Cracking: Determining Conditions for Extensive Olivine Serpentinization

Contact Info

Product

Resources

About