K–Ar, 40Ar–39Ar ages and magnetostratigraphy of Brunhes and Matuyama lava sequences from La Palma Island

Abstract

We have applied geological mapping, magnetostratigraphy and unspiked K–Ar and 40Ar–39Ar datings to reconstruct the main volcanic stages of the northern part of La Palma, an oceanic volcanic island of the Canaries archipelago. Based on 57 new K–Ar and 40Ar–39Ar ages, mostly concordant with the astronomic polarity time scale, three main volcanic units are distinguished: the Garafı́a volcano, and the Lower and Upper Taburiente volcanoes. This entirely subaerial activity took place between 1722±25 and 440±8 ka. The oldest stage, corresponding to the Garafı́a volcano, encompasses the post-Olduvai–Cobb Mountain period, with isotopic age determinations ranging from 1722±25 to 1208±8 ka. The oldest lava flows of the Taburiente volcano, which was active between 1.08±0.04 and 833±11 ka, recorded the Jaramillo normal polarity subchron and younger reversed flows were erupted during the upper part of the post-Jaramillo–Matuyama period. All the Upper Taburiente lava flows were erupted during the Brunhes chron and have ages ranging from 770±11 to 440±8 ka. The age of the Garafı́a collapse lies between 1.20±0.05 and 1.08±0.04 Ma, while the Cumbre Nueva collapse occurred at about 550 ka.