Rhyolitic pumice in the basaltic pyroclasts from the 1971 eruption of Teneguía volcano,Canary Islands

Fragments of acid pumice have been found among the basic pyroclastics thrown out by the Teneguía volcano during its explosive phases. The presence of these pumice fragments brings up the problem of their origin and their relationships to the mechanism of the eruption.The composition of the analysed samples coincides exactly with the low temperature trough in petrogeny's residua system, albits-orthoclase-silica. The samples can be classified as rhyolites and trachytes.The authors propose that the pumice was produced by the fusion of the acid phase in a subvolcanic complex located beneath the island of La Palma.