Fault systems and stress patterns on emerged oceanic ridges: a case study in Iceland

Abstract

A tectonic study, based primarily on fault slip analysis, was carried out in three areas of Iceland (the northern coast near Husavik, the western coast near Akranes-Borgarnes and the eastern coast). The results of paleostress reconstructions show: 1. (1) a major direction of extension trending perpendicular to the rift axis i.e. E-W in the north and NW-SE in the south; 2. (2) a close relationship between strike-slip faulting and normal faulting, with the mean axes of minimum stress coinciding; 3. (3) the existence of an additional compressional stress that trends perpendicular to the rift axis. Permutations of stresses σ 1 and σ 2 that induce changes from normal to strike-slip faulting may be proposed to explain the particular distribution of individual paleostresses. These permutations are related to the presence of magma chambers, dyke injection processes, or elastic rebound subsequent to extensional failure of the crust.