Magmatic evolution of the differentiated ultramafic, alkaline and carbonatite intrusion of Vuoriyarvi (Kola Peninsula, Russia). A LA-ICP-MS study of apatite
- 作者：S. Brassinnes ; E. Balaganskaya and D. Demaiffe
- 关键词：Carbonatite ; Kola ; Apatite ; LA-ICP-MS ; Fractional crystallisation
- 刊名：Lithos
- 出版年：2005
- 期刊代码：54_00244937
- 类别：ear
- 出版时间：2005
- 卷：85
- 期：1-4
- 页码：76-92
- 文件大小：587 K
摘要
The nature of the petrogenetic links between carbonatites and associated silicate rocks is still under discussion (i.e., [Gittins J., Harmer R.E., 2003. Myth and reality of the carbonatite–silicate rock “association”. Period di Mineral. 72, 19–26.]). In the Paleozoic Kola alkaline province (NW Russia), the carbonatites are spatially and temporally associated to ultramafic cumulates (clinopyroxenite, wehrlite and dunite) and alkaline silicate rocks of the ijolite–melteigite series [Kogarko, 1987, Kogarko et al., 1995, Verhulst et al., 2000, Dunworth and Bell, 2001 and Woolley, 2003]. In the small (≈ 20 km2) Vuoriyarvi massif, apatite is typically a liquidus phase during the magmatic evolution and so it can be used to test genetic relationships. Trace elements contents have been obtained for both whole rocks and apatite (by LA-ICP-MS). The apatites define a single continuous chemical evolution marked by an increase in REE and Na (belovite-type of substitution, i.e., 2Ca2+ = Na+ + REE3+). This evolution possibly reflects a fractional crystallisation process of a single batch of isotopically homogeneous, mantle-derived magma.
The distribution of REE between apatite and their host carbonatite have been estimated from the apatite composition of a carbonatite vein, belonging to the Neskevara conical-ring-like vein system. This carbonatite vein is tentatively interpreted as a melt. So, the calculated distribution coefficients are close to partition coefficients. Rare earth elements are compatible in apatite (D > 1) with a higher compatibility for the middle REE (DSm : 6.1) than for the light (DLa : 4.1) and the heavy (DYb : 1) REE.