Three-dimensional magnetic models of La Gomera (Canary Islands): insights into the early evolution of an ocean island volcano

Abstract

An aeromagnetic data set from the island of La Gomera was studied through two inversemodeling approaches that produced complementary views of the inner structure of this volcanic island:(1) a variable magnetization model that identified the main lateral magnetization contrasts and (2) aconstant magnetization model that imaged the main magnetic source by assuming that it was a uniformlymagnetized body. The modeling reveals intense magnetizations beneath the northern part of La Gomera,which occupy an important portion of the northern submarine edifice, correspond well with outcrops of thesubmarine volcano (Basal Complex), and confirm that most of the magnetic signal revealed by aeromagneticmapping in the Canary Islands is due to the intense magnetizations of the intrusive complexes (plutonicbodies and dike complexes) emplaced during the initial stages of growth of the volcanic edifices. Theconsistency of our models with the results of a previous gravimetric study suggests that these intrusivecomplexes are denser and more magnetic than the surrounding rocks. The location of the main magneticsource reinforces the interpretation, first suggested by geological evidence, that the submarine and earlysubaerial growth of La Gomera started to the north of the present island. The elongated shape of theseintrusive complexes with a nearly E‐W strike agrees with the orientation of analogous structures on Tenerifeand Gran Canaria, suggesting that the initial formation of the central islands of the Canary Archipelago wascontrolled by a set of regional fractures in a strike‐slip tectonic framework.