Internal structure of Tenerife (Canary Islands) based on gravity, aeromagnetic and volcanological data

Gravity and magnetic methods have been applied to the Tenerife Island, to p rovide new information about its internal structure. For this study, 365 gr avity stations covering the central part of the island have been selected. The anomalous density maps at different depths were obtained by means of an inversion global adjustment, on fixed density contrast. to describe the th ree-dimensional (3D) geometry of the anomalous bodies. On the other hand, s everal analysis techniques, such as reduction to the pole, spectral analysi s, low-pass filtering, terrain correction and forward modelling, were appli ed to process the high-resolution data obtained in an aeromagnetic survey, completed with marine and terrestrial data. The joint analysis of gravity and magnetic anomalies has shown tectonic and volcanic features that define some fundamental aspects of the structural f ramework and volcanic evolution of the island. A strong gravity anomaly pro duced by a large and deep source has been associated with an uplifted block of the basement beneath the southern part of Tenerife. The sources of the observed gravity highs from 8 km b.s.l. may be associated with the growth o f the submarine shield stage that was clearly controlled by regional tecton ic. The long-wavelength magnetic anomalies reveal highly magnetic sources, inte rpreted as gabbro-ultramafic cumulates associated with the root zone of a l arge dyke swarm. This intrusive body could be topped by the emplacement zon e of magma chambers that correlate with a magnetic horizon at 5.7 +/- 0.8 k m depth. Rooted in this highly magnetic zone, two dike-like structures can be associated with the magmatic feeding system of large recent basaltic vol canoes. A shallow magnetic horizon (1.4 km a.s.l.) can be correlated with t he bottom phonolites of the Las Canadas Edifice. In the central part of the island the coincidence of some gravity and magne tic lows is consistent with the presence of low-density and low-magnetic ma terials, that infill a collapsed caldera system. The structures close to th e surface are characterised by low-density areas connected with the recent volcanism, in particular the minimum over the Teide volcano, Hydrothermal a lteration is assumed to be the cause of a short-wavelength magnetic low ove r the Teide volcano. (C) 2000 Elsevier Science B.V. All rights reserved.