Metamorphic Record of High-pressure Dehydration of Antigorite Serpentinite to Chlorite Harzburgite in a Subduction Setting (Cerro del Almirez, Nevado-Filabride Complex, Southern Spain)

Padrón‐Navarta, José Alberto; Sánchez‐Vizcaíno, Vicente López; Garrido, Carlos J.; Gómez-Pugnaire, María Teresa

doi:10.1093/petrology/egr039

Cited by 156 publications

(103 citation statements)

References 86 publications

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“…Oxidation of sulfur is accompanied by a modest reduction of ferric iron (50 to 30% Fe 3+ /Fe tot ) as reported in chemical analyses on exhumed serpentinites (Padron-Navarta et al, 2011). Sulfur is subsequently transferred to arc-volcanoes where it is degassed as SO 2 .…”

Section: Accepted Manuscriptmentioning

confidence: 75%

“…Sulfidation at various lithospheric depths is also recognized to occur, and except at the seafloor surface, deposits of sulfate minerals seem unimportant (Padron-Navarta et al, 2011;Alt et al, 2012). The fate of these species in subduction zones is documented by petrological and geochemical studies, although the details of the reaction paths involved are unkown (Wallace, 2005;Evans, 2012).…”

mentioning

confidence: 99%

“…Based on modern subduction rates (see also Li and Lee, 2006), assuming subduction of serpentinite having Fe 3+ /Fetot ratio of 0.35 (Padron-Navarta et al, 2011) and considering an average degree of serpentinization of the oceanic lithosphere as given in Schmidt and Poli (1998) and Li and Lee (2006), it can be calculated that ca. 0.5-210 15 g/year of Fe 2 O 3 is buried in the mantle by serpentinite subduction.…”

mentioning

confidence: 99%

“…The deep burial of these rocks must increase the mantle fO 2 by increasing its oxygen / cation ratio (see Evans (2012) FMQ-3 to FMQ). This estimate takes into account the fact that a part of the ferric iron buried in subduction zones is returned via arc-volcanoes (following Lecuyer and Ricard, 1999) but it does not consider the amount of ferric iron stored in the cold mantle wedge, which contains serpentine and chlorite minerals (Guillot et al, 2001), both being known to store large amount of ferric iron (Evans, 2008;Padron-Navarta et al, 2011).…”

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The redox geodynamics linking basalts and their mantle sources through space and time

et al. 2015

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International audienceThe Earth's mantle redox state regulates the fate and transfer of metals by magmatism, buffers the igneous inputs of volcanic gases in the atmosphere and controls the depth of mantle melting. It therefore strongly affects ore forming processes, biogeochemical cycles and deep geodynamic processes. This paper reviews the current knowledge on the redox state of the upper mantle and of magmas produced by mantle melting. The geochemical processes likely to control and modify it through space and time are discussed.We analyze the link between the redox state of magma and that of their mantle source and we conclude that melts produced in the mantle may well all equilibrate in a narrow range of oxidation state, where the speciation of sulfur in basalts shifts from sulfide to sulfate, that is, FMQ+1 ± 1 (1 log unit below and above the oxygen fugacity buffered by the assemblage fayalite–magnetite–quartz). Subsequently, degassing and partial crystallization of melts can affect their redox states, producing most of the range of redox states observed on magmas reaching Earth's surface. The asthenosphere sourcing basaltic magmas may therefore be more oxidized than the FMQ−1 value generally assumed.We also discuss redox transfers from the mantle to the atmosphere via volcanic degassing and the backward fluxes via subduction processes of the hydrothermalized oceanic lithosphere. Arc-magmas are oxidized (up to FMQ+4) but it is unclear when this feature is acquired since strongly oxidized primary arc-basalts have yet to be found. The oxidizing event may be the assimilation of slab-derived SO3-rich fluids by primary basalt generated by decompression melting in the mantle-wedge.Overall, subduction must result in a transfer of oxygen from the Earth's surface down to the mantle. This must imply that subduction and its initiation can hardly be the trigger of the great oxidation event at the end of the Archaean. In contrast, the cooling of the Earth's interior through time must have impacted on the redox state of basalts, by decreasing the depth of mantle melting. According to the long-established vertical stratification of the Earth's mantle, ancient primary magmas are therefore likely to have been more reduced (i.e. < FMQ−3) than present-day ones. However, geochemical observations on ancient basalts suggest a constant oxidation state since the early Archaean.We conclude that large uncertainties in the calibration of mineralogical oxygen barometer probably explains why we have difficulties in identifying (i) ancient primary basalts being more reduced than recent ones and (ii) primary basalts from subduction zones being as oxidized as arc-lavas reaching the surface. Finally, the degree of mantle melting is certainly a key issue for the interpretation of the mantle oxidation state. Extremely oxidized melts, enriched in C–H–S volatile species, produced by very low degrees of mantle melting may be indicative of an Earth's mantle more oxidized than usually considered

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Section: Accepted Manuscriptmentioning

confidence: 75%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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The redox geodynamics linking basalts and their mantle sources through space and time

et al. 2015

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“…In the Liz/Atg-and Atg-serpentinites no retrograde phases (e.g. talc, chrysotile amphiboles; Padrón-Navarta et al, 2011;Müntener et al, 2000) are observed suggesting that they were little affected by retrograde metamorphism. In the Liz/Atgserpentinites, antigorite is observed to have formed at the expense of mesh and bastite textures (Figs.…”

Section: The Lanzo Massifmentioning

confidence: 99%

Evolution of Fe redox state in serpentine during subduction

Debret

Andréani

Muñoz

et al. 2014

Earth and Planetary Science Letters

101

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Crustal Metasomatism at the Slab‐Mantle Interface in a Continental Subduction Channel: Geochemical Evidence From Orogenic Peridotite in the Sulu Orogen

Chen

Zheng

et al. 2018

JGR Solid Earth

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To understand crust‐mantle interactions in a continental subduction channel, we carried out a combined study of whole‐rock elements and Sr‐Nd isotopes, mineral elements, and whole‐rock and mineral O isotopes in orogenic peridotite and its host gneiss from the Sulu orogen in China. The results indicate that the peridotite originated from highly depleted subcontinental lithospheric mantle beneath the North China Craton and underwent three episodes of metasomatism via crustally derived fluids. The peridotite was offscraped from the subcontinental lithospheric mantle wedge base and experienced petrographic transformation from a spinel peridotite to a garnet peridotite during continental subduction from forearc to subarc depths. The peridotite underwent the first episode of metasomatism via aqueous solutions at high‐pressure conditions. Afterward, the peridotite underwent a second episode of metasomatism by carbonate melts at ultrahigh‐pressure conditions and a third episode of metasomatism by aqueous solutions at high‐pressure conditions. While the aqueous solution was derived from the metamorphic dehydration of the subducting/exhuming continental crust at the forearc depths, the carbonate melts were produced by partial melting of the ultrahigh‐pressure metasedimentary rocks in the exhuming continental crust at subarc depths. These metasomatic agents did not originate from the gneiss directly hosting the peridotite but from another part of the deeply subducted continental crust that was not in direct contact with the peridotite. Therefore, the orogenic peridotite recorded the geochemical transfer from the subducting crust into the mantle in the continental subduction zone.

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Metamorphic Record of High-pressure Dehydration of Antigorite Serpentinite to Chlorite Harzburgite in a Subduction Setting (Cerro del Almirez, Nevado-Filabride Complex, Southern Spain)

Cited by 156 publications

References 86 publications

The redox geodynamics linking basalts and their mantle sources through space and time

The redox geodynamics linking basalts and their mantle sources through space and time

Evolution of Fe redox state in serpentine during subduction

Crustal Metasomatism at the Slab‐Mantle Interface in a Continental Subduction Channel: Geochemical Evidence From Orogenic Peridotite in the Sulu Orogen

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