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Title: Geology and mineralization of the Gatumba area, Rwanda: Present state of knowledge
Authors: Dewaele, Stijn ×
Tack, Luc
Fernandez-Alonzo, Max
Boyce, Adrian
Muchez, Philippe
Schneider, Jens
Cooper, Gavin
Wheeler, Kenneth #
Issue Date: 2008
Publisher: Université nationale du Rwanda
Series Title: Etudes Rwandaises vol:16 pages:6-23
Abstract: The Gatumba area is charactenzed by the presence of numerous mineralized pegmatites, which are related to the so-called "tin granites" that formed at -986 Ma. The
pegmatites are dated at -968 Ma, of which some are associated with columbite and cassiterite mineralization. The columbite precipitated during crystallization of the
pegmatites. Also beryl, spodumene, amblygonite and rare phosphates formed during this crystallization. The pegmatites underwent intense alteration by hydrothermal
processes: albitization, sericitization (i.e., greisenization in the old literature) and
muscovitization. The cassiterite mineralization in the pegmatitic bodies is associated with the two latter alteration stages. Sericitization and cassiterite precipitation occurred from a H20-CO2-(X)-NaCl-KCl fluid (Throt between 240 and 370°C; TmIce between -19.2 and -8.2°C). Based on the structural setting, petrographical observations, geochemistry of the so-called tin granites, stable and radiogenic isotope geochemistry, we propose a
model in which Sn was remobilized from primary magmatic rocks by a hydrothermal system that was installed after the crystallization of the granites and pegmatites, and precipitated in structurally controlled locations, together with sericitization/muscovitization of parts of the pegmatites.
ISSN: 1011-4874
Publication status: published
KU Leuven publication type: DI
Appears in Collections:Division of Geology
× corresponding author
# (joint) last author

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