Mineral Chemistry of Leucitites from Visoke Volcano (Virunga Range, Rwanda): Petrogenetic Implications

G. Marcelot and J. Ph. Rançon
Laboratoire de Pétrologie, Université de Bretagne Occidentale 29287 Brest Cedex, France
Bureau de Recherches Géologiques et Minières, Département Géologie, BP 6009, 45060 Orléans Cedex, France

Abstract: The Visoke complex is one of the main Quaternary volcanic centres of the Virunga Range, located north of lake Kivu. Mineralogical (microprobe) data are given for two representative leucitite lavas; one sample contains a complex coarse-grained xenolith (phlogopite, diopside, leucite, titanomagnetite, perovskite and apatite) and megacrysts of pyroxene, phlogopite and olivine scattered in fine-grained leucite-rich host lava. Compared with the typical leucite-dominated, low-pressure phenocryst assemblage of the two samples studied, the chemical trends of ferromagnesian crystals suggest an earlier igneous event (high-pressure phenomenon) strongly related to the leucite-bearing magma suite.

Keywords: mineral chemistry • leucitites • Visoke Volcano • Rwanda

Mineralogical Magazine; December 1988 v. 52; no. 368; p. 603-613; DOI: 10.1180/minmag.1988.052.368.05
© 1988, The Mineralogical Society
Mineralogical Society (www.minersoc.org)