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

Abstract

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.