Alkaline Rocks and Carbonatites of the World

Setup during HiTech AlkCarb: an online database of alkaline rock and carbonatite occurrences



Occurrence number: 
Longitude: -86.8811, Latitude: 16.1223

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).

Quaternary (<200,000 years) (Kepezhinskas et al., 2020)

KEPEZHINSKAS, N., KAMENOV, G.D., FOSTER, D.A. & KEPEZHINSKAS, P., 2020. Petrology and geochemistry of Alkaline Basalts and Gabbroic xenoliths from Utila Island (Bay Islands, Honduras): Insights into back – Arc processes in the Central American Volcanic Arc. Lithos 352-353 105306

Fig 1. Map of Utila Island (Kapezhinskas et al., 2020, Fig 1.b.)
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith