667 § E-mail address: lena@lenusik.usr.pu.ru ¶ E-mail address: bobby@gfz-potsdam.de The Canadian Mineralogist Vol. 44, pp. 667-692 (2006) THE BEHAVIOR OF RARE-EARTH AND LITHOPHILE TRACE ELEMENTS IN RARE-METAL GRANITES: A STUDY OF FLUORITE, MELT INCLUSIONS AND HOST ROCKS FROM THE KHANGILAY COMPLEX, TRANSBAIKALIA, RUSSIA ElEna V. BaDanIna § Geochemistry Department, St. Petersburg State University, Universitetskaja Emb. 7/9, St. Petersburg 199034, Russia RoBERt B. tRUMBUll ¶ GeoForschungsZentrum Potsdam, Sektion 4.2, Telegrafenberg, D-14473 Potsdam, Germany PEtER DUlSKI GeoForschungsZentrum Potsdam, Sektion 3.3, Telegrafenberg, D-14473 Potsdam, Germany MIchaEl WIEDEnBEcK anD Ilya V. VEKSlER GeoForschungsZentrum Potsdam, Sektion 4.2, Telegrafenberg, D-14473 Potsdam, Germany lUDMIla F. SyRItSo Scientiic Research Institute of Earth Crust, St. Petersburg State University, St.Petersburg 199034, Russia aBStRact We have determined trace-element concentrations in luorite mineral separates, host granites and residual melts trapped in quartz from a well-documented sequence of differentiated li–F-rich granites in the Khangilay complex, transbaikalia, Russia, which are associated with ta (orlovka) and W (Spokojnoje) mineralization. Fluorite is a common accessory mineral in most units of the granite sequence and in greisen veins from their hydrothermal aureoles. this allows us to monitor the behavior of REE and other luorite-compatible trace elements during the magma evolution, and to compare magmatic and hydrothermal REE signatures directly. With increasing differentiation of the granites, REE abundances decrease, chondrite-normalized patterns become lat, and negative Eu anomalies more pronounced. Fluorite separates from the respective granites show similar REE patterns and 5–10 times higher concentrations (up to 4000 ppm total REE). First-order features of the whole-rock, luorite and melt-inclusion REE characteristics are the presence of extreme negative Eu anomalies and the strong lanthanide tetrad effects in the more evolved units. Samples with the tetrad effect also show strong separation of geochemical twin elements (y–ho, Zr–hf). although melt- inclusion data prove that the lanthanide tetrad effect developed during the magmatic stage, the process cannot be explained by simple fractional crystallization. Partitioning of REE to a F-bearing hydrothermal solution also is unlikely because hydrothermal luorite from associated veins and greisen does not show complementary W-tetrads. We suggest that the tetrad effect and devia- tions of element ratios observed in this and other highly evolved F-rich granites are caused by separation of a F-rich hydrosaline melt. this is consistent with results of experimental partitioning studies of immiscible silicate and hydrosaline melts. Keywords: melt inclusions, tetrad effect, rare-earth elements, luorite, rare-metal granites, hydrosaline melt, immiscibility, second- ary-ion mass spectrometry, orlovka, Spokojnoje, transbaikalia, Russia. SoMMaIRE Nous avons établi la concentration d’éléments traces dans des concentrés de luorite, le granite hôte, et des reliquats magma- tiques piégés dans le quartz provenant de séquences bien différenciées de granites enrichis en li–F du complexe de Khangilay, en Transbaïkalie, Russie, qui sont associées à une minéralisation en Ta (Orlovka) et W (Spokojnoje). La luorite est un accessoire commun dans la plupart des unités intrusives et dans les greisen et les veines hydrothermales de leurs aureoles hydrothermales. C’est ce qui nous permet de contrôler le comportement des terres rares et autres éléments traces compatibles avec la luorite au