Constraining Chronology and Time-Space Evolution of Holocene Volcanic Activity on the Capelo Peninsula (Faial Island, Azores): The Paleomagnetic Contribution

Tuesday, 16 December 2014
Anita Di Chiara1, Fabio Speranza2, Massimiliano Porreca2, Adriano HG Pimentel3, Francesca D'ajello Caracciolo2 and Josè Pacheco4, (1)IAG Institute of Astronomy, Geophysics and Atmospheric Sciences, Sao Paulo, Brazil, (2)National Institute of Geophysics and Volcanology, Rome, Italy, (3)Centro de Informação e Vigilância Sismovulcânica dos Açores, Ponta Delgada, Portugal, (4)Centro de Vulcanologia e Avaliação de Riscos Geológicos, Universidade dos Açores, Ponta Delgada, Portugal
Faial is one of the most volcanically active islands of the Azores Archipelago. Historical eruptions occurred on the Capelo Peninsula (westernmost sector of the island) during A.D. 1672–1673 and more recently in A.D. 1957–1958. The other exposed volcanic products of the peninsula are so far loosely dated within the Holocene. Here, we present a successful attempt to correlate scoria cones and lava flows yielded by the same eruption on the Capelo Peninsula using paleomagnetic data from 31 sites (10 basaltic scoriae, 21 basaltic lava flows). In the investigated products, we recognize at least six prehistoric clusters of volcanic activity, whereas 11 lava sites are correlated with four scoria cones. Dating was conducted by comparing our paleomagnetic directions with relocated Holocene reference curves of the paleosecular variation of the geomagnetic field from France and the UK. We find that the studied volcanic rocks exposed on the Capelo Peninsula are younger than previously believed, being entirely formed in the last 8 k.y., and that the activity intensified over the last 3 k.y. Our study confirms that paleomagnetism is a powerful tool for unraveling the chronology and characteristics of Holocene activity at volcanoes where geochronological age constraints are still lacking