Halogens and noble gases in serpentinites and secondary peridotites: Implications for seawater subduction and the origin of mantle neon

Kendrick, Mark A.; Scambelluri, Marco; Hermann, Jörg; Padrón‐Navarta, José Alberto

doi:10.1016/j.gca.2018.03.024

Cited by 53 publications

(44 citation statements)

References 100 publications

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“…If halogens are retained during this phase transformation, substantial amounts of I‐rich halogens can be transported into the deep mantle. Kendrick et al () reported that even secondary peridotites formed by the final breakdown of serpentine retain halogens with concentrations up to 1 order of magnitude higher than the depleted mantle. The hydrated oceanic lithospheric mantle is often invoked to account for subduction of volatiles and fluid‐mobile elements into the deep mantle.…”

Section: Discussionmentioning

confidence: 99%

Halogen Heterogeneity in the Lithosphere and Evolution of Mantle Halogen Abundances Inferred From Intraplate Mantle Xenoliths

Kobayashi

Sumino

Burgess

et al. 2019

Geochem Geophys Geosyst

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We present halogen, noble gas, and major and trace element compositions of mantle xenoliths from intraplate settings (Eifel, Kilbourne Hole, San Carlos, and Hawaii). The xenoliths show a wide range of halogen elemental ratios, which form two arrays centered on the halogen composition of mid-ocean ridge basalts. The samples on the array toward high I/Cl value have relatively low Cl concentration and low ratios of highly incompatible elements relative to heavy rare earth elements, whereas the samples on the array toward low Br/Cl value have higher Cl concentration and trace elements ratios. The detailed mechanisms to account for these signatures are equivocal at present. However, they are most likely to be related to secondary processes of volatile loss during partial melting and secondary phase formation during interaction with melts. The common primary mid-ocean ridge basalt-like halogen ratios in mantle xenoliths from different parts of the globe indicate that the mantle itself must have a relatively uniform composition over a wide scale. The mantle has maintained its halogen composition over billion year timescales without being affected by I-rich halogens being transported into the mantle. Mass balance calculations suggest that, in order to maintain the I/Cl ratio of the convecting mantle over 2 Gyr, the I/Cl ratio of the subducted halogens must be no more than several times higher than the present-day mantle value. Plain Language Summary Elemental and isotopic compositions of volatile species such ashalogens, noble gases, hydrogen, and carbon can be used to trace the evolution of these species in the Earth. Halogens are important tracers of subduction recycling of surface volatiles into the mantle: however, there is only limited understanding of halogens in the mantle. Here we provide new halogen data of mantle xenoliths from intraplate settings. The mantle xenoliths show a wide range of halogen elemental ratios, which are expected to be related to later processes after the xenoliths formed. A similar primary halogen component is present in the xenoliths sampled from different localities. This suggests that the mantle has the uniform halogen composition over a wide scale. The halogen composition in the convecting mantle is expected to have remained constant over more than 2 billion years, despite subduction of iodine-rich halogens. We used mass balance calculations to gain understanding into evolution rate of I/Cl ratio in the mantle. Calculations suggest that, in order to maintain the I/Cl ratio of the mantle over 2 Gyr, the I/Cl ratio of the subducted halogens must be no more than several times higher than the present-day mantle value.

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Section: Discussionmentioning

confidence: 99%

Halogen Heterogeneity in the Lithosphere and Evolution of Mantle Halogen Abundances Inferred From Intraplate Mantle Xenoliths

Kobayashi

Sumino

Burgess

et al. 2019

Geochem Geophys Geosyst

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“…The F/Cl, Br/Cl and I/Cl ratios of the depleted mantle (grey fields) [6] and seawater (dashed lines) [54] are shown, along with the average concentrations of F, Cl, Br and I in the depleted mantle (black stars) [6]. Figures modified after [55]. (a) Bromine and Cl concentrations in all serpentinites are elevated with respect to the average depleted mantle but are strongly correlated along a linear trend defined by the Br/Cl ratio of the mantle and seawater, suggesting their coherent behaviour during serpentinization (hydration) and subduction (dehydration).…”

Section: Incorporation Of Halogens By Abyssal Serpentinitesmentioning

confidence: 99%

“…Available data of FME for subducted abyssal serpentinites are mostly from oceanic lithosphere produced at slow-spreading ridges, such as serpentinites of the Greater Antilles extinct arc in Dominican Republic [48], ophiolitic massifs of the Western Alpine-Northern Apennine chain in Italy [41,43,44,47,53] and the Cerro del Almirez massif in Spain [55]. Buoyant oceanic lithosphere formed at such slow-spreading ridges subducts at shallow angles and forms accretionary prisms, where the upper portion of the incoming oceanic lithosphere with sediments is scraped off and obducted [62].…”

Section: Halogen Behaviour During Serpentinite Subductionmentioning

confidence: 99%

“…As the slab descends, the lizardite +/− chrysotile transition to antigorite occurs at~300-400 • C [28] and is considered to be accompanied by the release of additional water [32] and certain FME [65]. This is supported by much higher concentrations of Cl, Br and I in seafloor and obducted abyssal lizardite serpentinites than subducted abyssal antigorite serpentinites [41,48,53,55]. This is also in agreement with lower Cl contents in other subducted lithologies (i.e., metasediments and metabasites) compared to their pre-subduction equivalents [60,[66][67][68].…”

Section: Lizardite-antigorite Transitionmentioning

confidence: 99%

“…Some antigorite serpentinites display lower Br/Cl and I/Cl ratios compared to their lizardite-bearing counterparts ( Figure 4A), suggesting a preferential loss of Br and I relative to Cl during the serpentine phase transition [44,53,55], whereas others have slightly higher ratios ( Figure 4A) [48]. Given the limited data available for HP serpentinites and the uncertainty regarding the exact composition of their protoliths, it is difficult to fully assess these subtle differences in halogen behaviour.…”

Section: Lizardite-antigorite Transitionmentioning

confidence: 99%

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Abyssal Serpentinites: Transporting Halogens from Earth’s Surface to the Deep Mantle

Pagé

Hattori

2019

Minerals

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Serpentinized oceanic mantle lithosphere is considered an important carrier of water and fluid-mobile elements, including halogens, into subduction zones. Seafloor serpentinite compositions indicate Cl, Br and I are sourced from seawater and sedimentary pore fluids, while F may be derived from hydrothermal fluids. Overall, the heavy halogens are expelled from serpentinites during the lizardite–antigorite transition. Fluorine, on the other hand, appears to be retained or may be introduced from dehydrating sediments and/or igneous rocks during early subduction. Mass balance calculations indicate nearly all subducted F is kept in the subducting slab to ultrahigh-pressure conditions. Despite a loss of Cl, Br and I from serpentinites (and other lithologies) during early subduction, up to 15% of these elements are also retained in the deep slab. Based on a conservative estimate for serpentinite thickness of the metamorphosed slab (500 m), antigorite serpentinites comprise 37% of this residual Cl, 56% of Br and 50% of I, therefore making an important contribution to the transport of these elements to the deep mantle.

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Tectonic Settings of Potassic Igneous Rocks

Müller¹,

Groves²

2018

Potassic Igneous Rocks and Associated Gold-Copper Mineralization

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Halogens and noble gases in serpentinites and secondary peridotites: Implications for seawater subduction and the origin of mantle neon

Cited by 53 publications

References 100 publications

Halogen Heterogeneity in the Lithosphere and Evolution of Mantle Halogen Abundances Inferred From Intraplate Mantle Xenoliths

Halogen Heterogeneity in the Lithosphere and Evolution of Mantle Halogen Abundances Inferred From Intraplate Mantle Xenoliths

Abyssal Serpentinites: Transporting Halogens from Earth’s Surface to the Deep Mantle

Tectonic Settings of Potassic Igneous Rocks

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