26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: The Vema Lithospheric Section revisited (Articolo in rivista)

Type

• Articolo in rivista (Classe)
• Prodotto della ricerca (Classe)

Label

• 26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: The Vema Lithospheric Section revisited (Articolo in rivista) (literal)

Anno

• 2009-01-01T00:00:00+01:00 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi

• 10.1016/j.epsl.2009.05.046 (literal)

Alternative label

• Cipriani A (1), Bonatti E (1,2,4), Brunelli D (3,4), Ligi M (4) (2009)
  26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: The Vema Lithospheric Section revisited
  in Earth and planetary science letters
  (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori

• Cipriani A (1), Bonatti E (1,2,4), Brunelli D (3,4), Ligi M (4) (literal)

Pagina inizio

• 87 (literal)

Pagina fine

• 95 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#altreInformazioni

• DOI: 10.1016/j.epsl.2009.05.046 (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume

• 285 (literal)

Rivista

• Earth and planetary science letters (Rivista)

Note

• ISI Web of Science (WOS) (literal)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni

• 1. Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY 10964 USA 2. Univ Roma La Sapienza, Dipartimento Sci Terra, I-00187 Rome, Italy 3. Univ Modena & Reggio Emilia, Dipartimento Sci Terra, I-41100 Modena, Italy 4. CNR, Ist Sci Marine, Sede Bologna Geol Marina, I-40129 Bologna, Italy (literal)

Titolo

• 26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: The Vema Lithospheric Section revisited (literal)

Abstract

• Temporal variations of temperature and composition of the mantle upwelling below a 80-km long segment of the Mid Atlantic Ridge were reconstructed from 20 to 4 Ma ago from peridotites sampled along a >300-km long section of oceanic lithosphere (Vema Lithospheric Section or VLS) exposed south of the Vema transform at 11 degrees N [Bonatti, E., Ligi, M., Brunelli, D., Cipriani, A., Fabretti, P., Ferrante, V., Gasperini, L., Ottolini, L., 2003. Mantle thermal pulses below the Mid-Atlantic Ridge and temporal variation in the formation of oceanic lithosphere, Nature, 423, 499-505]. We extended this time interval from 26 to 2 Ma by sampling mantle ultramafics at 18 new sites along the VLS. Peridotite orthopyroxene, clinopyroxene and spinel chemistry suggest a weak trend of decreasing extent of melting of the mantle from 26 to 18.5 Ma ago with superimposed short-wavelength (similar to 4 Ma) oscillations followed by a steady increase of degree of melting from 18.5 to 2 Ma ago, with superimposed 3-4 Ma oscillations. Temporal variations of crustal thickness inferred from the Residual Mantle Bouguer Anomaly calculated from gravity data reveal similar trends. The older (26 to 18.5 Ma) and the younger (18.5 to 2 Ma) mantle suites differ in cpx Na2O content and CaO/Al2O3 ratio, suggesting that not only the thermal regime, but also the composition of the mantle source might have been different in the two suites. The two trends are separated by a similar to 1.4 Ma-long stretch (from 18.2 to 16.8 Ma) where deformed ultramafic mylonites prevail, indicating probably an interval of nearly a-magmatic lithospheric emplacement at ridge axis, corresponding to a thermal minimum. Spatially offset correlation along the VLS of crustal thickness (i.e., quantity of basaltic melt released by the mantle) and mantle peridotite degree of melting led to an estimate of similar to 16.1 mm/a for the solid mantle average velocity of upwelling, a value close to the average half spreading rate for the 26 Ma interval covered by the VLS. However, peridotite clinopyroxene geothermometry shows oscillations superimposed on a decreasing trend of calculated equilibration temperature from 26 to 18.5 Ma ago, followed by a steady increase from 16 to 4 Ma ago, suggesting that the solid mantle upwelling velocity varied through time. These results hint at the existence of similar to 10-20 Ma cycles in the activity of the northern Mid Atlantic Ridge. (literal)

Prodotto di

• Processi geologici, dal vulcanismo alla sismicità, che portano alla formazione della crosta terrestre al di sotto dei mari (TA.P01.011.002) (Modulo)
• Marine science institute (ISMAR) (Istituto)

Autore CNR

• MARCO LIGI (Persona)
• DANIELE BRUNELLI (Unità di personale esterno)
• ENRICO BONATTI (Unità di personale esterno)

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• Parole chiave di "26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: The Vema Lithospheric Section revisited" (Insieme di parole chiave)

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Autore CNR di

• MARCO LIGI (Persona)
• ENRICO BONATTI (Unità di personale esterno)
• DANIELE BRUNELLI (Unità di personale esterno)

Prodotto

• Marine science institute (ISMAR) (Istituto)
• Processi geologici, dal vulcanismo alla sismicità, che portano alla formazione della crosta terrestre al di sotto dei mari (TA.P01.011.002) (Modulo)

Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#rivistaDi

• Earth and planetary science letters (Rivista)

Insieme di parole chiave di

• Parole chiave di "26 million years of mantle upwelling below a segment of the Mid Atlantic Ridge: The Vema Lithospheric Section revisited" (Insieme di parole chiave)