• Citer

New mineralogical and geochemical data on the Vuorijarvi ultramafic, alkaline and carbonatitic complex (Kola Region, NW Russia)

par Brassinnes, Stéphane ;Demaiffe, Daniel ;Balaganskaya, Elena;Downes, Hilary
Référence Periodico di Mineralogia, 72, SPEC. ISSUE 1, page (79-86)
Publication Publié, 2003

Article révisé par les pairs

• Détails
• Contenu

Résumé :

The Vuorijarvi massif belongs to the famous Devonian (380-360 Ma) alkaline and carbonatitic province of Kola (NW Russia). It is a complex polyphase intrusion made of ultramafic rocks, ijolites-melteigites, carbonatites and related phoscorites. Ultramafic rocks (mainly clinopyroxenites) have been interpreted as cumulates, with variable amounts of trapped interstitial liquid. Ijolites are quite complex: some are aegirine-augite and nepheline cumulates, others are partly recrystallised rocks. Carbonatites and phoscorites (apatite-forsterite-magnetite rocks) are genetically linked; the latter correspond to cumulates of silicate and oxide minerals crystallised from a carbonatitic magma. Two generations of carbonatite have been recognized, calcitic varieties and dolomitic varieties. The three groups of rocks (ultramafic rocks, alkaline silicate rocks and carbonatites) have similar initial Nd-Sr isotopic compositions which suggest their cogenetic character. Apatite is a liquidus phase in the three main lithologies; it presents a continuous chemical evolution trend interpreted in terms of isomorphous substitution 2Ca2+ = REE3+ + Na+, which is compatible with a fractional crystallisation model.