|
|||||
|
|
Magmatic evolution of the differentiated ultramafic, alkaline and carbonatite intrusion of Vuoriyarvi (Kola Peninsula, Russia). A LA-ICP-MS study of apatite |
|
| Authors: | S Brassinnes E Balaganskaya D Demaiffe |
| Institution: | aUniversite Libre de Bruxelles, Géochimie isotopique (CP160/02), 50 Av. Roosevelt, 1050 Bruxelles, Belgium bGeological Institute, Kola Science Centre RAS, Fersman Street 14, Apatity 184209, Russia |
| Abstract: | 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. |
| Keywords: | Carbonatite Kola Apatite LA-ICP-MS Fractional crystallisation |
| 本文献已被 ScienceDirect 等数据库收录！ | |