Utila

Utila Island is the westernmost and smallest of the major Bay Islands, Honduras, playing host to the Utila Volcanic Centre. This centre is found in the north-western portion of the island erupting through carbonate rocks of the south Caribbean carbonate platform, with eruptives of alkaline basaltic and trachybasaltic composition. Flows form lobate cliffs displaying columnar joining interbedded with palagonite lapilli tuff, with the vent facies forming conical topographic highs at Colibri Hill and Pumpkin Hill. Alkaline basalt/trachybasalt lavas feature phenocrystic olivine, augite, and bytownite-labradorite plagioclase and xenolithic coral fragments and gabbro. The latter xenoliths are cognate, as deduced from similar mineral chemistry to their host rock, with the notable addition of apatite and poikilitic kaersutite enclosing chadacrysts of olivine, plagioclase, clinopyroxene, and Fe-Ti oxides. Both gabbros and basalts are alkaline (sodic) to subalkaline, thought to be derived from melting of an enriched mantle source fertilised by fluids exsolved from a subducting slab. Geochemical data including whole rock major and trace element, radiogenic isotopic, and mineral chemical can be found in Kepezhinskas et al. (2020).