CRYSTALLIZATION OF LOPARITE IN ALKALINE FLUID-MAGMATIC SYSTEMS (from experimental and mineralogical data)
N.I. Suk, A.R. Kotel’nikov, A.A. Viryus
Keywords: Loparite, experiment, fluid, crystallization, Lovozero alkaline massif
Abstract
We studied loparite-containing rocks (lujaurites, juvites, foyaite-juvites, etc.) sampled from a complex of differentiated rocks and, partly, from a complex of eudialytic lujaurites of the Lovozero alkaline massif. Zoned crystals of loparite (the zoning is due to variations in Ti, Nb, REE, Sr, and Th contents) were examined by microprobing. We also carried out experimental studies of loparite formation in complex silicate–salt systems including sodium carbonate, chloride, fluoride, or sulfate at 400–1200ºC and 1–2 kbar. They show that the composition of loparites depends on the physicochemical conditions of their formation (fluid composition) and that natural loparite can crystallize in a broad range of temperatures. The produced loparite crystals are zonin as a result of variations in Ti, Nb, La, Ce, Y, Ca, and Sr contents, which is probably related to the kinetic specifics of crystallization. Their zoning is similar to that of loparites of the Lovozero massif.
|
