Contributions to Mineralogy and Petrology

, Volume 127, Issue 4, pp 369–382

Partial melting below Tubuai (Austral Islands, French Polynesia)

  • Martial Caroff
  • René C. Maury
  • Gérard Guille
  • Joseph Cotten

DOI: 10.1007/s004100050286

Cite this article as:
Caroff, M., Maury, R., Guille, G. et al. Contrib Mineral Petrol (1997) 127: 369. doi:10.1007/s004100050286

Abstract

Process identification diagrams based on trace element data show that mafic lavas from Tubuai, including alkali basalts, basanites, analcitites and nephelinites, result from different degrees of partial melting of an isotopically homogeneous mantle source. Our fractionation-corrected data are consistent with a batch melting model or a dynamic melting model involving a threshold value for melt separation close to 1% and degrees of melting ranging from 5–8% (alkali basalts) to 1.5–3% (nephelinites). The relative source concentration pattern, calculated using an inverse numerical method, shows an enrichment in highly incompatible elements. We propose that the Tubuai lava suite was derived from a two-stage partial melting process. Melting first affected the plume material located within the transition zone between garnet and spinel domains, producing alkali basalts and basanites. Then, the melting zone migrated upwards to the base of the overlying spinel-bearing lithospheric mantle, producing highly silica-undersaturated lavas. The lower lithosphere had previously been enriched by intrusion of pyroxenite veins representing plume-derived melts which percolated away from the main magma conduits.

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Martial Caroff
    • 1
  • René C. Maury
    • 1
  • Gérard Guille
    • 2
  • Joseph Cotten
    • 1
  1. 1.Laboratoire de Pétrologie, UMR n°6538 “Domaines Océaniques”, Université de Bretagne Occidentale, B.P. 809, 29285 Brest, FranceFR
  2. 2.Groupe Télédétection et Risques Sismiques, DASE, CEA, B.P. 12, 91680 Bruyères le Chatel, FranceFR