The Las Canadas caldera (Tenerife, Canary Islands): an overlapping collapse caldera generated by magma-chamber migration

The Las Canadas caldera is one of the most important geological structures of Tenerife. Stratigraphic. structural, volcanological, petrological, geoch ronological, and geophysical data suggest that the Las Canadas caldera resu lted from multiple vertical collapse episodes that occurred during the cons truction of the Las Canadas edifice Upper Group. Three long-term (greater t han or equal to 200 ka) cycles of phonolitic explosive activity. each culmi nating with a caldera collapse. have been identified in the Upper Group, Du ring the construction of the Upper Group, the focus of felsic volcanism mig rated from first to east. Using the results of field observations, experime ntal analogue models and numerical studies, we propose that the formation o f the overlapping Las Canadas collapse caldera is related to the migration of the associated magma chamber. Our model implies that each collapse of th is overlapping caldera partly. or completely, destroyed the feeding magma c hamber. This destruction led to changes in the local stress field that favo ured the formation of a new chamber at one side of the previous one, result ing in magma-chamber migration, The proposed model accounts for the formati on of the Las Canadas caldera. In particular, it explains the geometrical r elationships, stratigraphy and chronology of the caldera wall deposits. Com parison with other overlapping collapse calderas suggests that our model ma y apply to other overlapping calderas. (C) 2000 Elsevier Science B.V. All r ights reserved.