Li in minerals from the Ilímaussaq alkaline intrusion

• Main Authors: J. C. Bailey, H. Bohse, R. Gwozdz, J. Rose-hansen
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1993
• Subjects: Greenland; Lovozero; Ilimaussaq
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.489.1259; http://2dgf.dk/xpdf/bull40-03-04-288-299.pdf

Li was analysed by instrumental neutron activation analysis and Cerenkov counting in 120 mineral samples (30 species) from the Ilimaussaq alkaline intrusion, South Greenland. More than 0.23 wt. % Li (0.5 wt. % Li20) is found in polylithionite, neptunite, riebeckite, Na-cookeite, ephesite, arfvedsonite, gerasimovskite and astro-phyllite. Arfvedsonite (200-2500 ppm Li) carries the bulk of Li in most of the highly alkaline rocks. Li-Mg and Li-F relations indicate that the distribution of Li is con-trolled by the structure of minerals, their absolute contents of Mg and F and the fractionation stage within the intrusion. Li is probably linked with F in the fluid state and this linkage continues into crystallising phases where Li occupies sites which also accommodate Mg. Li/Mg and Li/F ratios of Ilimaussaq rocks and minerals are higher than in equivalent materials from the Lovozero intrusion (Kola, Russia). The Li-Mg-Fe2+ geochemical association at Ilimaussaq (Fe2 +»Mg) and Lovozero (Fe2+>Mg) contrasts with the commercially important Li-rich but Mg-Fe2+-poor association found in certain granite pegmatites and greisenised granites.