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| Titel |
New insights into the origin of the subduction component in Late Oligocene magmatism in the Ronda peridotite (southern Spain): geodynamic implications for the western Mediterranean |
| VerfasserIn |
María Isabel Varas-Reus, Carlos J. Garrido, Claudio Marchesi, Delphine Bosch, Károly Hidas, Antonio Acosta-Vigil |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072601
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| Zusammenfassung |
| Several tectonic scenarios have been proposed for the Tertiary evolution of the Betic-Rif
chain in the westernmost Mediterranean. Recent studies on late, mantle-derived Cr-rich
websterite dykes in the Ronda peridotite have revealed recycling the involvement of sources
of continental detrital sediments in the waning magmatic stage of the Ronda peridotite
(Marchesi et al., 2012). This new data are consistent with a subduction-related setting for the
late evolution of the Alboran lithospheric mantle before its final intracrustal emplacement in
the early Miocene (Garrido et al., 2011). Detailed structural studies of Ronda plagioclase
peridotites show that large-scale, ductile folding of peridotites—associated to the
development of LT-LP plagioclase peridotite tectonites and ultramylonites—occurred during
a contractional event before intracrustal emplacement of peridotites (Hidas et al., 2013).
These authors have proposed that this event was related to inversion of a back-arc basin,
followed by failed subduction initiation that ended into the intracrustal emplacement of
peridotite into the Alboran wedge. This new structural data leads us to hypothesize that the
crustal component observed in late, Cr-rich websterite might come from fluids produced
by dehydration of underthrusted crustal units in the earliest stages of subduction
initiation.
Here we present new trace element and Sr-Nd-Pb-Hf isotopic data in whole rocks from
Flysch sediments from the Betic cordillera and the underlying crustal units of the Ronda
massif, which may account for the timing and geochemical signature of the Ronda Cr-rich
pyroxenites dykes. These units correspond to the Flysch trough composed of turbiditic
deposits, formed in the region between Iberia and Africa during Late Oligocene-Early
Miocene, and the underlying crustal unit of the Ronda peridotite known as the Blanca unit.
These new data are used to constrain the potential role of different crustal sources in the
generation of the Late Oligocene subduction-related magmatism in the Ronda peridotite,
and its implications for geodynamic models of the western Mediterranean in the
Cenozoic.
REFERENCES
Garrido, C. J., F. Gueydan, G. Booth-Rea, J. Precigout, K. Hidas, J. A. Padrón-Navarta,
and Marchesi C. . (2011) Garnet lherzolite and garnet-spinel mylonite in the Ronda
peridotite: Vestiges of Oligocene backarc mantle lithospheric extension in the western
Mediterranean, Geology, 39(10), 927-930.
Hidas, K., Booth-Rea, G, Garrido, C. J., Martínez-Martínez, J. M., Padrón-Navarta, J.
A., Konc, Z., Giaconia, F., Frets, E., and Marchesi, C. (2013) . Backarc basin inversion and
subcontinental mantle emplacement in the crust: kilometre-scale folding and shearing at the
base of the proto-Alborán lithospheric mantle (Betic Cordillera, southern Spain): Journal of
the Geological Society, London.
Marchesi, C., Garrido, C. J., Bosch, D., Bodinier, J.-L., Hidas, K., Padrón-Navarta, J. A.,
and Gervilla, F. (2012) A Late Oligocene Suprasubduction Setting in the Westernmost
Mediterranean Revealed by Intrusive Pyroxenite Dikes in the Ronda Peridotite (Southern
Spain): The Journal of Geology, 120 (2), 237-247. |
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