Corundum-bearing and spinel-bearing symplectites in ultrahigh-pressure eclogites record high-temperature overprint and partial melting during slab exhumation

Abstract + + + + + ∘ C) of the eclogite at pressures of 0.8–0.9 GPa. Dehydration partial melting reactions occurred during the breakdown of muscovite, which leads to the formation of thin plagioclase films (silicate melts) along grain (garnet, rutile, quartz) boundaries. Mass balance calculations indicate that the development of CPB and SPB symplectites after phengite requires the introduction of Al, Ca, Na, and Fe and loss of Si, Mg, and K. However, the formation of SP symplectites after paragonite requires the input of Mg, Ca, and Fe and removal of Si, Al, and Na. By summarizing the occurrence and growth mechanism of corundum- and spinel-bearing symplectites in global UHP terranes, we find that such symplectites can form by both the subsolidus replacement of an Al-rich anhydrous mineral (kyanite) and the dehydration melting of an Al-rich hydrous phase during high-temperature metamorphism. This study reveals that muscovite-bearing eclogites may experience multiple episodes of partial melting during the slab exhumation, not only at the high-pressure (HP) exhumation stage but also at the lower-pressure metamorphic overprinting stage. Kyanite is a reaction product during the HP partial melting, whereas the low-pressure (LP) melting will consume kyanite. We propose that the occurrence of corundum- and spinel-bearing symplectites after muscovite in eclogites is a potential mineralogical indicator of LP melting in exhumed slabs.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Corundum-bearing and spinel-bearing symplectites in ultrahigh-pressure eclogites record high-temperature overprint and partial melting during slab exhumation ; volume:35 ; number:4 ; year:2023 ; pages:569-588 ; extent:20 ; European journal of mineralogy ; 35, Heft 4 (2023), 569-588 (gesamt 20)

Contributors, Places and Time

• Creator: Tang, Pan ; Guo, Shun

Further information

• DOI: 10.5194/ejm-35-569-2023
• URN: urn:nbn:de:101:1-2023080304212858943774
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 14.08.2025, 10:55 AM CEST