The South Sandwich Islands
Description / Table of Contents:
Candlemas Island is a recently active volcanic island in the South Sandwich Islands group. The southern part of the island is composed of anorthite-olivine-phyric basalt lava flows alternating with scoria layers, is extinct and ice-capped. The northern part of Candlemas Island is a young volcanic centre, consisting of a scoria cone rising to 229 m. above sea level, surrounded by lava flows which radiate up to 0 [dot] 8 km. from the foot of the cone. The lavas of northern Candlemas Island are called andesites; they are almost aphyric, contain up to 64 per cent of SiO2, and are unusually rich in iron and poor in potash. Xenoliths of strongly porphyritic lava and gabbroic material, which are probably crystal accumulates, are present in the andesites. The andesites and xenoliths are believed to have originated by a process of rock genesis involving simple fractional crystallization of basaltic parent magma.
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33,  S. : Ill., graph. Darst., Kt