Deep sourced fluids for peridotite carbonation in the shallow mantle wedge of a fossil subduction zone: Sr and C isotope profiles of OmanDP Hole BT1B

ObesoiD, Juan Carlos de; Kelemen, P. B.; Leong, James Andrew; MenzeliD, Manuel D; ManningiD, Craig; GodardiD, Marguerite; Cai, Yue; Bolge, Louise

doi:10.1002/essoar.10507483.1

Cited by 2 publications

(15 citation statements)

References 69 publications

(73 reference statements)

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“…However, this is not consistent with the Sr isotope data on the sole in core from Hole BT1B. Measured and age‐corrected Sr isotope ratios in the metamorphic sole are consistently lower than corresponding ratios in the listvenites (de Obeso, Kelemen, et al., 2022).…”

Section: Discussionmentioning

confidence: 72%

“…On the other hand, it is clear that most listvenites have higher Sr concentrations than typical Samail ophiolite peridotites and the Banded Unit (de Obeso, Kelemen, et al., 2022). This observation suggests that both Sr and Ca were added during low temperature alteration, along with H 2 O and CO 2 .…”

Section: Discussionmentioning

confidence: 99%

“…Present day Sr isotope ratios in listvenites and serpentinites from MoD Mtn range from ∼0.708 to 0.715 (de Obeso, Kelemen, et al., 2022; Falk & Kelemen, 2015). Using current Rb/Sr contents in these samples, age corrected 87Sr/86Sr ratios at 96 Ma range from ∼0.708 to 0.714, much higher than the range of Sr ratios in Samail ophiolite peridotites (0.703–0.707, Benoit et al., 1999; Gerbert‐Gaillard, 2002; Gregory & Taylor, 1981; Lanphere et al., 1981; McCulloch et al., 1980, 1981), the range in Late Cretaceous to modern seawater (∼0.7075 to 0.7081), or the range in peridotite‐hosted ground water in the Samail ophiolite (∼0.7065 to 0.7092, Weyhenmeyer, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…Instead, pelagic, clastic units of the underlying Hawasina sedimentary rocks have measured and age‐corrected Sr isotope ratios that span the same range as those in the listvenites (de Obeso, Kelemen, et al., 2022). Thus, these sedimentary units in the Hawasina may be analogous to subducted sedimentary rocks that produced CO 2 ‐bearing fluids which, in turn, formed the MoD Mountain listvenites.…”

Section: Discussionmentioning

confidence: 99%

“…The compositions of 5 wt% aqueous fluid in equilibrium with pelitic and carbonate‐bearing lithologies from the Hawasina Formation at 400°C–700°C and 0.5–2.0 GPa were calculated. For example, a dilute fluid was equilibrated with the rock composition of sample OM20‐17 (de Obeso, Kelemen, et al., 2022), containing 0.06 wt% total carbon (Table S2 in Supporting Information S1). The CaO content of OM20‐17 was below detection.…”

Section: Methodsmentioning

confidence: 99%

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Listvenite Formation During Mass Transfer into the Leading Edge of the Mantle Wedge: Initial Results from Oman Drilling Project Hole BT1B

et al. 2022

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This paper provides an overview of research on core from Oman Drilling Project Hole BT1B and the surrounding area, plus new data and calculations, constraining processes in the Tethyan subduction zone beneath the Samail ophiolite. The area is underlain by gently dipping, broadly folded layers of allochthonous Hawasina pelagic sediments, the metamorphic sole of the Samail ophiolite, and Banded Unit peridotites at the base of the Samail mantle section. Despite reactivation of some faults during uplift of the Jebel Akdar and Saih Hatat domes, the area preserves the tectonic “stratigraphy” of the Cretaceous subduction zone. Gently dipping listvenite bands, parallel to peridotite banding and to contacts between the peridotite and the metamorphic sole, replace peridotite at and near the basal thrust. Listvenites formed at less than 200°C and (poorly constrained) depths of 25–40 km by reaction with CO2‐rich, aqueous fluids migrating from greater depths, derived from devolatilization of subducting sediments analogous to clastic sediments in the Hawasina Formation, at 400°–500°. Such processes could form important reservoirs for subducted CO2. Listvenite formation was accompanied by ductile deformation of serpentinites and listvenites—perhaps facilitated by fluid‐rock reaction—in a process that could lead to aseismic subduction in some regions. Addition of H2O and CO2 to the mantle wedge, forming serpentinites and listvenites, caused large increases in the solid mass and volume of the rocks. This may have been accommodated by fractures formed as a result of volume changes, mainly at a serpentinization front.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Listvenite Formation During Mass Transfer into the Leading Edge of the Mantle Wedge: Initial Results from Oman Drilling Project Hole BT1B

et al. 2022

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Geochemical Profiles Across the Listvenite‐Metamorphic Transition in the Basal Megathrust of the Semail Ophiolite: Results From Drilling at OmanDP Hole BT1B

et al. 2021

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Listvenites (or listwaenites) are produced by CO 2 -metasomatism of mantle-derived ultramafic rocks (Falk & Kelemen, 2015;Halls & Zhao, 1995). They are composed mainly of quartz and carbonate (magnesite and/or dolomite, ±Cr-or Mg-rich micas ± chlorite) and are often associated with serpentinites, ophicarbonates and/ or talc. Since their first description in the literature (Rose, 1837), they have been investigated for one of their main characteristics: the occurrence of mineralizations concentrating economically valuable metals, such as

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Deep sourced fluids for peridotite carbonation in the shallow mantle wedge of a fossil subduction zone: Sr and C isotope profiles of OmanDP Hole BT1B

Cited by 2 publications

References 69 publications

Listvenite Formation During Mass Transfer into the Leading Edge of the Mantle Wedge: Initial Results from Oman Drilling Project Hole BT1B

Listvenite Formation During Mass Transfer into the Leading Edge of the Mantle Wedge: Initial Results from Oman Drilling Project Hole BT1B

Geochemical Profiles Across the Listvenite‐Metamorphic Transition in the Basal Megathrust of the Semail Ophiolite: Results From Drilling at OmanDP Hole BT1B

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