Journal of Volcanology and Geothermal Research, 27 (1986) 299--322 299 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands THE HISTORY OF INTRUSIVE ACTIVITY ON THE ISLAND OF LA PALMA (CANARY ISLANDS) H. STAUDIGEL 1 , G. FERAUD 2 and G. GIANNERINI 2 1Scripps Institution of Oceanography, A-015, La Jolla, CA 92093, U.S.A. and Lamont Doherty Geological Observatory of Columbia University, Palisades, NY 10964, U.S.A. 2 Laboratoire de G~ologie et G~ochimie, ERA CNRS 888, Universit~ de Nice, Parc Valrose, F-06034 Nice CEDEX, France (Received February 24, 1985; revised and accepted July 22, 1985) ABSTRACT Staudigel, H., Feraud, G. and Giannerini, G., 1986. The history of intrusive activity on the island of La Palma, (Canary Islands). J. Volcanol. Geotherm. Res., 27 : 299--322. The island of La Palma, located in the northwest of the Canary archipelago, consists of two main geological units. (1) The subaerial extrusive Coberta Series covers most of the island and consists of alkali basaltic lavas, phonolitic plugs, and pyroclastic rocks, erupted between 1.61Ma and the Recent. (2) The basement complex is exposed in the Barranco de Las Angustias and the Caldera de Taburiente and consists of the submarine intrusive and extrusive Seamount Series and a basal plutonic complex. Alkali basaltic dikes of different ages and orientations intruded in both units. Three groups of dikes and sills can be distinguished, based on their field relationships, petrography, geochemistry and ages. The oldest Group I, represent the feeder dikes to the Seamount Series, intruded between 2.9 and 4.0 Ma B.P. They were originally steep, with a N05°W strike and perpendicular to the originally nearly flat bedding of the layered Seamount Series. Subsequent to emplacement, Group I dikes and the extrusives of the Seamount Series were rotated into their present orientation. Group II sills, intruded parallel to the bedding of the Seamount Series (45/230), are coeval with or younger than Group I, but older than the erosional unconformity separating the Coberta and the basement complex (i.e. ~l.6Ma; ~4.0Ma). Group llI dikes, the feeder dikes of the Coberta Series, occur in the Coberta Series and the basement complex and are generally steep with variable strike. Two apparent maxima in strike are interpreted as a radial dike swarm with a dominant strike of NO6°E. K/At age data suggest that Group III dikes intruded between 0.63 and 0.73Ma in the western portion of La Palma, between 0.51 and 1.30Ma in the north, and in the Cumbre Nueva between 0.53 and 0.70Ma. There is no correlation of intrusive age and direction. Group I and III dikes and volcanic lineations on La Palma display a dominant northern direction of maximum horizontal compressive stress, throughout the geological history of La Palma. Similar intrusive directions were found on other Canary Islands (Gran Canaria: Brey and Schmincke, 1980 ; Fuerteventura : Fuster et al., 1968b), but not every island of the archipelago is consistent with the ob- servations from La Palma. Sills, originally horizontal, (Group II) comprise >50 vol % of the volcanic edifice of the La Palma seamount and highlight the importance of intrusive processes for island LDGO Contribution No. 3936. 0877-0273/86/$03.50 © 1986 Elsevier Science Publishers B.V.