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dc.contributor.author
Whattam, Scott A.
dc.contributor.author
Früh-Green, Gretchen L.
dc.contributor.author
Cannat, Mathilde
dc.contributor.author
De Hoog, Jan C.M.
dc.contributor.author
Schwarzenbach, Esther M.
dc.contributor.author
Escartin, Javier
dc.contributor.author
John, Barbara E.
dc.contributor.author
Leybourne, Mathew I.
dc.contributor.author
Williams, Morgan J.
dc.contributor.author
Rouméjon, Stéphane
dc.contributor.author
Akizawa, Norikatsu
dc.contributor.author
Boschi, Chiara
dc.contributor.author
Harris, Michelle
dc.contributor.author
Wenzel, Kirsten
dc.contributor.author
McCaig, Andrew
dc.contributor.author
Weis, Dominique
dc.contributor.author
Bilenker, Laura
dc.date.accessioned
2022-06-17T08:50:40Z
dc.date.available
2022-02-19T05:52:17Z
dc.date.available
2022-06-17T08:50:40Z
dc.date.issued
2022-04-05
dc.identifier.issn
0009-2541
dc.identifier.issn
1872-6836
dc.identifier.other
10.1016/j.chemgeo.2021.120681
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/533357
dc.description.abstract
International Ocean Discovery Program (IODP) Expedition 357 drilled 17 shallow sites distributed ~10 km in the spreading direction (from west to east) across the Atlantis Massif oceanic core complex (Mid-Atlantic Ridge, 30°N). Mantle exposed in the footwall of the Atlantis Massif oceanic core complex is predominantly nearly wholly serpentinized harzburgite with subordinate dunite. Altered peridotites are subdivided into three types: (I) serpentinites, (II) melt-impregnated serpentinites, and (III) metasomatic serpentinites. Type I serpentinites show no evidence of melt-impregnation or metasomatism apart from serpentinization and local oxidation. Type II serpentinites have been intruded by gabbroic melts and are distinguishable in some cases on the basis of macroscopic and microscopic observations, e.g., mm-cm scale mafic-melt veinlets, rare plagioclase (˂0.5 modal % in one sample) or by the local presence of secondary (replacive) olivine after orthopyroxene; in other cases, ‘cryptic’ melt-impregnation is inferred on the basis of incompatible element enrichments. Type III serpentinites are characterized by silica metasomatism manifest by alteration of orthopyroxene to talc and amphibole, and by anomalously high anhydrous SiO2 concentrations (59–61 wt%) and low MgO/SiO2 values (0.48–0.52). Although many chondrite-normalized rare earth element (REE) and primitive mantle-normalized incompatible trace element anomalies, e.g., negative Ce-anomalies, are attributable to serpentinization, other compositional heterogeneities are due to melt-impregnation. On the basis of whole rock incompatible trace elements, a dominant mechanism of melt-impregnation is distinguished in the central and eastern serpentinites from fluid-rock alteration (mostly serpentinization) in the western serpentinites, with increasing melt-impregnation manifest as a west to east increase in enrichment in high-field strength elements and light REE. High degrees of melt extraction are evident in low whole-rock Al2O3/SiO2 values and low concentrations of Al2O3, CaO and incompatible elements. Estimates of the degree of melt extraction based on whole rock REE patterns suggest a maximum of ~20% non-modal fractional melting, with little variation between sites. As some serpentinite samples are ex situ rubble, the magmatic histories observed at each site are consistent with a local source (from the fault zone) rather than rafted rubble that would be expected to show more heterogeneity and no spatial pattern. In this case, the studied sites may provide a record of enhanced melt-rock interactions with time, consistent with proposed geological models. Alternatively, sites may signify heterogeneities in these processes at spatial scales of a few km.
en_US
dc.language.iso
en
en_US
dc.publisher
Elsevier
en_US
dc.subject
IODP Expedition 357
en_US
dc.subject
Atlantis Massif
en_US
dc.subject
Mantle peridotite
en_US
dc.subject
Fluid-rock interaction
en_US
dc.subject
Melt-rock interaction
en_US
dc.title
Geochemistry of serpentinized and multiphase altered Atlantis Massif peridotites (IODP Expedition 357): Petrogenesis and discrimination of melt-rock vs. fluid-rock processes
en_US
dc.type
Journal Article
dc.date.published
2022-02-10
ethz.journal.title
Chemical Geology
ethz.journal.volume
594
en_US
ethz.journal.abbreviated
Chem. geol.
ethz.pages.start
120681
en_US
ethz.size
19 p.
en_US
ethz.grant
Hydration and carbonation of mantle peridotite: Drilling the Atlantis Massif (MAR 30°N) and the Samail ophiolite (Oman)
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.publication.place
Amsterdam
en_US
ethz.publication.status
published
en_US
ethz.grant.agreementno
163187
ethz.grant.fundername
SNF
ethz.grant.funderDoi
10.13039/501100001711
ethz.grant.program
Projekte MINT
ethz.date.deposited
2022-02-19T05:52:26Z
ethz.source
SCOPUS
ethz.eth
yes
en_US
ethz.availability
Metadata only
en_US
ethz.rosetta.installDate
2022-06-17T08:50:48Z
ethz.rosetta.lastUpdated
2022-06-17T08:50:48Z
ethz.rosetta.versionExported
true
ethz.COinS
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