The field relations of the Las Cañadas Volcanoes, Tenerife, Canary islands

Summary

The subaerial basement shield of Tenerife is composed largely of basanite and ankaramite flows intercalated with tuffs and agglomerates. Near the centre of the islands, in the area now known as Las Cañadas, extensive volcanism of intermediate and salic composition followed the shield building stage and produced the Upper and Lower Cañadas Series. These Series are exposed in the walls of a large collapse structure, the Portillo-Tauce escarpment. Detailed mapping of the structures within this escarpment indicates that the volcanics were erupted from a series of poorly defined centres along an east-west fissure system, one of two or possibly three such systems that have dominated the major sub-aerial volcanic growth of Tenerife.

In the Lower Cañadas Series trachy basanite, plagioclase phonolites, and phonolite flows were erupted, along with phonolitic pumice lapilli, scoria, and at least one ash-flow. Following this, the Upper Cañadas Series represented a restriction of volcanism to local centres in which phonolites were the dominant rock type. Viscous flows, thick lapilli deposits and abundant volcanoclastites form the bulk of this stage.

Post-collapse activity north of the escarpment has built the twin volcanoes, Viejo and Teide. The freshness of their flows and the generally good preservation of the volcanic structures suggests that they are no older than Quaternary in age. Both volcanoes have displayed central and satellite activity. Viejo is surmounted by a dormant caldera, whilst Teide displays weak fumerole activity from the top crater El Piton.