Cold plumes trigger contamination of oceanic mantle wedges with continental crust-derived sediments: Evidence from chromitite zircon grains of eastern Cuban ophiolites
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Proenza Fernández, Joaquín Antonio; González Jiménez, José Manuel; García Casco, Antonio; Gervilla Linares, FernandoEditorial
Elsevier BV
Materia
Zircon U-Pb geochronology Chromitites Cold plumes Ophiolites
Fecha
2017-12-30Referencia bibliográfica
Proenza, J. A., González-Jiménez, J. M., Garcia-Casco, A., Belousova, E., Griffin, W. L., Talavera, C., ... & Gervilla, F. (2018). Cold plumes trigger contamination of oceanic mantle wedges with continental crust-derived sediments: Evidence from chromitite zircon grains of eastern Cuban ophiolites. Geoscience Frontiers, 9(6), 1921-1936.
Patrocinador
This research was financially supported by FEDER Funds, the Spanish Project CGL2015-65824 granted by the Spanish “Ministerio de Economía y Competitividad” to JAP, and the Ramón y Cajal Fellowship RYC-2015-17596 to JMGJ. This is also a contribution from the ARC National Key Centre for Geochemical Evolution and Metallogeny of Continents (www.es.mq.edu.au/GEMOC) and the ARC Centre of Excellence for Core to Crust Fluid Systems. Y.R-A acknowledges support by the Deutsche Forschungsgemeinschaft (DFG) grant RO4174/2-1. Supportwas also provided by the technical staff of the SHRIMP facility at Curtin University.Resumen
The origin of zircon grains, and other exotic minerals of typical crustal origin, in mantle-hosted ophiolitic
chromitites are hotly debated.We report a population of zircon grains with ages ranging from Cretaceous
(99 Ma) to Neoarchean (2750 Ma), separated from massive chromitite bodies hosted in the mantle
section of the supra-subduction (SSZ)-type Mayarí-Baracoa Ophiolitic Belt in eastern Cuba. Most
analyzed zircon grains (n = 20, 287 +/- 3 Ma to 2750 +/- 60 Ma) are older than the early Cretaceous age of
the ophiolite body, show negative εHf(t) (+/-26 to +/-0.6) and occasional inclusions of quartz, K-feldspar,
biotite, and apatite that indicate derivation from a granitic continental crust. In contrast, 5 mainly
rounded zircon grains (297 +/- 5 Ma to 2126 +/- 27 Ma) show positive εHf(t) (þ0.7 to þ13.5) and occasional
apatite inclusions, suggesting their possible crystallization from melts derived from juvenile (mantle)
sources. Interestingly, younger zircon grains are mainly euhedral to subhedral crystals, whereas older
zircon grains are predominantly rounded grains. A comparison of the ages and Hf isotopic compositions
of the zircon grains with those of nearby exposed crustal terranes suggest that chromitite zircon grains
are similar to those reported from terranes of Mexico and northern South America. Hence, chromitite
zircon grains are interpreted as sedimentary-derived xenocrystic grains that were delivered into the
mantle wedge beneath the Greater Antilles intra-oceanic volcanic arc by metasomatic fluids/melts
during subduction processes. Thus, continental crust recycling by subduction could explain all populations
of old xenocrystic zircon in Cretaceous mantle-hosted chromitites from eastern Cuba ophiolite.
We integrate the results of this study with petrological-thermomechanical modeling and existing geodynamic
models to propose that ancient zircon xenocrysts, with a wide spectrum of ages and Hf isotopic
compositions, can be transferred to the mantle wedge above subducting slabs by cold plumes.