Embryos of TTGs in Gore Mountain garnet megacrysts from water-fluxed melting of the lower crust
dc.contributor.author
Ferrero, S.
dc.contributor.author
Wannhoff, Iris
dc.contributor.author
Laurent, Oscar
dc.contributor.author
Yakymchuk, Chris
dc.contributor.author
Darling, R.
dc.contributor.author
Wunder, Bernd
dc.contributor.author
Borghini, Alessia
dc.contributor.author
O'Brien, Patrick J.
dc.date.accessioned
2021-07-05T11:18:36Z
dc.date.available
2021-07-05T03:05:40Z
dc.date.available
2021-07-05T11:18:36Z
dc.date.issued
2021-09-01
dc.identifier.issn
0012-821X
dc.identifier.issn
1385-013X
dc.identifier.other
10.1016/j.epsl.2021.117058
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/492914
dc.description.abstract
The garnet megacrysts of Gore Mountain (Adirondacks, US) are world-renown crystals due to their size, up to 1 m in historical record, which makes them the largest known garnets on the planet. We show here that they are also host to the first primary inclusions of trondhjemitic melt found in natural mafic rocks. The petrological and experimental investigation of the inclusions, coupled with phase equilibrium modelling, shows that this melt is the result of H2O-fluxed partial melting at T>900 °C of a lower crustal gabbro. The compositional similarity between the trondhjemitic melt inclusions and tonalitic–trondhjemitic–granodioritic (TTGs) melts makes these inclusions a direct natural evidence that melting of mafic rocks generates TTG-like melts, and provides us with the possibility to clarify processes responsible for the formation of the early continental crust. These TTG embryos represent the trondhjemitic end-member of the melts whose emplacement at upper crustal levels, after being modified by mixing and crystallization-related processes, leads to the formation of the TTG terranes. Moreover, our study shows how the melt from H2O-fluxed melting of mafic lower crust has mismatched major and trace element signatures, previously interpreted as evidence of melting at very different pressures. This poses serious limitations to the established use of some chemical features to identify the geodynamic settings (e.g. subduction versus thickened crust) responsible for TTGs generation and the growth of early crust.
en_US
dc.language.iso
en
en_US
dc.publisher
Elsevier
en_US
dc.subject
TTG
en_US
dc.subject
megacrysts
en_US
dc.subject
nanogranitoids
en_US
dc.subject
crustal melting
en_US
dc.subject
garnet
en_US
dc.subject
trondhjemite
en_US
dc.title
Embryos of TTGs in Gore Mountain garnet megacrysts from water-fluxed melting of the lower crust
en_US
dc.type
Journal Article
dc.date.published
2021-06-29
ethz.journal.title
Earth and Planetary Science Letters
ethz.journal.volume
569
en_US
ethz.journal.abbreviated
Earth Planet. Sci. Lett.
ethz.pages.start
117058
en_US
ethz.size
13 p.
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.publication.place
Amsterdam
en_US
ethz.publication.status
published
en_US
ethz.date.deposited
2021-07-05T03:05:44Z
ethz.source
SCOPUS
ethz.eth
yes
en_US
ethz.availability
Metadata only
en_US
ethz.rosetta.installDate
2021-07-05T11:18:44Z
ethz.rosetta.lastUpdated
2022-03-29T10:15:22Z
ethz.rosetta.versionExported
true
ethz.COinS
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Journal Article [130417]