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Cristallisation fractionnée d'un magma basaltique alcalin : la série de la Chaîne des Puys (Massif central, France). II : Géochimie

1980; Volume: 103; Issue: 2 Linguagem: Inglês

10.3406/bulmi.1980.7405

0180-9210

B. Villemant, Jean‐Louis Joron, H. Jaffrézic, M. Treuil, René C. Maury, Robert Brousse,

Paleontology and Stratigraphy of Fossils

The behavior of hygromagmaphile elements (U, Th, Ta, La), and determination of mineral partition coefficients (feldspars, olivines, clinopyroxenes, amphibole, mica, titanomagnetite) are used for interpretation of trace elements analyses on samples of the Chaîne des Puys (Massif Central, France). Existence and unicity of the series generated by a fractional crystallization process are proved. We follow qualitatively the mineralogical evolution and we determine quantitatively some of the essential physical parameters : temperature, f[O₂], degree of différenciation (f) for any sample, proportions of each mineralogical phase which crystallizes and chemical composition of initial melt. The properties of this primary melt prove a direct mantellic origin, without initial contamination, which takes place in a geodynamic area of distention tectonic.