Olivine-hosted glass inclusions from Scoriae erupted in 1954–2000 at Mount Cameroon volcano, West Africa

Abstract

Concentrations of major, trace, and volatile elements are reported for olivine-hosted glass inclusions from intraplate-type, nepheline-normative trachybasaltic to basanitic scoria samples representing five historical eruptions (1954, 1959, 1982, 1999, and 2000) of Mount Cameroon (4.20°N, 9.17°E). Bulk-rock and mineral compositions are also reported for the same scoria samples and for lava samples from the same eruptions. Mineral analyses are also presented for a spinel–harzburgite mantle xenolith, which we suggest may be the youngest (and freshest) mantle sample known. Mount Cameroon magmas have eruption temperatures of 1150–1200 °C and have relatively high oxygen fugacities just above the trend of the synthetic Ni–NiO buffer. The most primitive glass inclusion analyzed is also the most volatile-rich, with 1.7 wt.% H 2O, 967 ppm CO 2, 1530 ppm F, 2400 ppm S, and 1270 ppm Cl. The Mount Cameroon F contents are the highest known for basaltic glasses. The relatively high CO 2 contents in Mount Cameroon glass inclusions support the interpretation that the CO 2 gas responsible for the Lakes Monoun and Nyos gas disasters is magmatic in origin.