La erupción y el tubo volcánico del Volcán Corona (Lanzarote, Islas Canarias)

Abstract

The island of Lanzarote, located at the eastem, oldest edge of the Canarian hotspot island-chain, has very sparse Holocene rejuvenation volcanism, possibly restricted to the 1824 and 1730 eruptions, ir1 agreement with the mature post-erosional stage of the island. The dating of the Corona Volcano, possibly the most recent eruptive event in the island before the historic eruptions, gives a mean 40Ar/.i9Ar age of 21 f 6.5 ka. This age agrees with the geological observations and the study of the Corona Volcano, particularly the large lava tube (7.6 km long, up to 25 m in diameter) formed in the initial stages of the eruption. The last 1.6 km of' this lava tube are at present submerged, ending at a depth of at least 80 m below the present sea level. Our interpretation is that the active lava tube could not have reached that depth and, therefore, the submerged part of the tube formed as the lava flowed on a coastal platform at least 1.6 km wider and at least 80 m below the present sea level, a circumstance that could only have been possible coinciding with a period of low sea-leve1 stand related to a maximum glacial, most probably the last one, at about 20 ka. The subsequent rise in sea level left the coastal platform and the end of the lava tube submerged. The age of the Corona Volcano eruption is constrained by the radioisotopic determinations in 21 + 6.5 ka and, concordantly, by the low sea-leve1 stand recorded between about 18 and 21 ka. The Corona Volcano eruption and lava tube therefore provide clear evidence of changes in sea level in the Canaries in relation to glaciations, and establish important constraints in the volcanic history of the island of Lanzarote.