Sulfur-containing monazite- (Ce) from late-stage mineral assemblages at the Kandaguba and Vuoriyarvi carbonatite complexes, Kola peninsula, Russia

摘要

At Kandaguba and Vuoriyarvi, monazite-(Ce) is an accessory mineral. It occurs in dolomite-calcite, siderite-dolomite carbonatites and quartz-carbonate veins developed in the country-rock fenites, and in quartz-bearing calcite-dolomite and dolomite carbonatites within the complexes. The monazite is dispersed in car-bonates and quartz, and associated with barite, strontianite, celestine, pyrite, sphale-rite, galena, hessite, gorceixite, goyazite, and ilmenorutile. At Vuoriyarvi monazite-(Ce) forms euhedral crystals, spherulites (split crystals) and their clusters ranging from 0.1 to 0.3mm in size. +2V_((meas.)) ~5 deg, #alpha#:c = 4 deg, #alpha# = 1.776-1.773, #beta# - #gamma#= 1.730, a = 6.70, b = 6.92, c = 6.39 A. #alpha#= 102.82 deg. V = 288.93 A. The Vuoriyarvi monazite contains chemical admixtures of SrO (0-4.36wt. percent), CaO (2.71-4.60), ThO_2(1.25-5.77), SO_3(0.62-3.12), and SiO_2 (0.29-0.70). At Kandaguba, monazite forms euhedral grains ranging from 0.05 to 0.2 mm in size. It contains admixtures of SrO (1.91-1.37 percent), CaO (0.79-1.71), ThO_2 (0.62-3.35), SO_3 (0-0.31), SiO_2 (0-0.35). At both occurrences the monazite is believed to precipitate from a carbohydrothermal solution when the conditions changed from alkaline to acidic.