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, geochronological, and geophysical data suggest that the Las Canadas caldera resulted from multiple vertical collapse episodes that occurred during the construction of the Las Canadas edifice Upper Group. Three long-term (greater than or equal to 200 ka) cycles of phonolitic explosive activity. each culminating with a caldera collapse. have been identified in the Upper Group, During the construction of the Upper Group, the focus of felsic volcanism migrated from first to east. Using the results of field observations, experimental analogue models and numerical studies, we propose that the formation of the overlapping Las Canadas collapse caldera is related to the migration of the associated magma chamber. Our model implies that each collapse of this overlapping caldera partly. or completely, destroyed the feeding magma chamber. This destruction led to changes in the local stress field that favoured the formation of a new chamber at one side of the previous one, resulting in magma-chamber migration, The proposed model accounts for the formation of the Las Canadas caldera. In particular, it explains the geometrical relationships, stratigraphy and chronology of the caldera wall deposits. Comparison with other overlapping collapse calderas suggests that our model may apply to other overlapping calderas. (C) 2000 Elsevier Science B.V. All rights reserved.