A Quaternary volcanic field lies to the north of Lake Yojoa and comprises a lava field of about 100 km2, with a number of scoria cones and domes in the central part, the whole lying within the Sula Graben. The earliest flows are tholeiitic but these were followed by alkali olivine basalts and trachytes. The latter comprise phenocrysts of anorthoclase and occasional corroded phenocrysts of andesine-labradorite rimmed by sanidine or anorthoclase, in a groundmass of aligned sanidine, augite with green aegirine-augite rims or aegirine, a little olivine, usually altered, magnetite and some zeolite. 87Sr/86Sr ratios through the series have been investigated (Mertzman, 1976).
MERTZMAN, S.A. 1976. A 87Sr/86Sr reconnaissance of the Lake Yojoa volcanic field, Honduras. Publicaceones Geologicas del ICAITI, 5: 99-106.
WADGE, G. and WOODEN, J.L. 1982. Late Cenozoic alkaline volcanism in the northwestern Caribbean: tectonic setting and Sr isotopic characteristics. Earth and Planetary Science Letters, 57: 35-46.
WILLIAMS, H. and MCBIRNEY, A.R. 1969. Volcanic history of Honduras. University of California Publications in Geological Sciences, 85: 1-101