Some considerations about the geometry of the boundaries between units of the South Iberian and Flysch Trough Domains from commercial seismic profiles and wells

Laburpena

The interpretation of commercial seismic lines coupled with well data, in an area situated north of the Gibraltar Straits, sheds light on the geometry of the boundaries between the Subbetic and Flysch Trough units; that is, respectively, the units derived from the South Iberian paleomargin and the units composed of rocks deposited in a deep trough which separated the South Iberian and the Maghrebian paleomargins. This trough was obliterated from the early Miocene onwards by the westward movements of the continental metamorphic rocks belonging to the Alboran Domain (Betic-Rif internal zones), which collided with the two paleomargins. In the external zones, two seismic units are differentiated, which according to the available correlation with commercial wells, correspond to the Flysch units laying over the Subbetic units. In the studied area, the depth of this boundary is situated mainly between 1,000m and 1,500m. Surface data together with seismic data show that within the Flysch Trough Domain -in the study area comprising the Aljibe and Algeciras units- Aljibe unit represents the uppermost unit, and that its structure corresponds with an imbricate thrust system.