Contemporary tectonic stress in northeastern Iberia. New results from borehole breakout analysis

In situ data on the orientation of tectonic stress in northern Iberia are scarce. Fault-slip and focal mechanism data show a variety of stress orientations difficult to interpret in terms of a general stress pattern. Breakout analysis performed on oriented caliper logs from 17 hydrocarbon exploration wells has provided new data on the orientation of tectonic stress in northeastern Iberia: the southern Pyrenees, the Ebro Basin and the northwestern Valencia Trough. The majority of breakout data indicate a rather consistent NE-SW to ENE-WSW directional signature of the larger horizontal principal stress orientation. This orientation differs significantly from the NW western European mean stress orientation. It is consistent with depth within the first 4.7 km of both the sedimentary fill and the sedimentary basins substrate and also within allochthonous thrust sheets in the southern Pyrenees and in the underlying autochthonous and parautochthonous foreland basin sediments.The first author was funded during part of this research by a grant of the European Commission (ERB4001GT933623). This work has been partially supported by the European Union through the Integrated Basin Studies project contract JOU2-CT92-0110, by the Deutsche Forschungsgemeinschaft through the SFB-108 (Karlsruhe Univ.SFB rep 423), by the Heidelberg Academy of Sciences and Humanities and by the Integrated Cooperation Action (between Germany and Spain), Spanish DGICYT-Coop Int HA-34-112-91.Peer Reviewe