IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS014 Poster presentation 2308
Paleostresses and recent tectonic activity of the Palomares-Carboneras
strike-slip faults (Eastern Betic Cordilleras, SE Spain)
Dr. Patricia Ruano
Dept. Geodinmica i Geofisica. U Barcelona Researcher
Jess Galindo-Zaldvar, Carlos Marn-Lechado
Palomares NNE-SSW and Carboneras NE-SW oriented strike-slip faults separate the southeastern end of
the Betic Cordilleras and the Alboran Sea- South Balearic basin thin continental crust. These faults
belong to the Trans Alboran shear zone- that has been considered a deep fracture zone with related
volcanism, crossing the Betic-Rif Cordilleras. The age of their activity has been broadly discussed on the
literature, and most of the authors suggest evidences of a minimum slip up to several tens of kilometers
since the Miocene, with sinistral strike-slip regime and extensional episodes. Although these faults have
not a clear present-day associated seismicity, there are local evidences of their recent activity. However,
up to date, there is no detailed discussion or analysis of the interaction between these two oblique
oriented major faults, with very straight cartographic traces.They should undergone a large geometrical
interaction that is not evidenced at their intersection. This contribution aims to discuss the relationships
between the activity of Palomares and Carboneras major faults, taking into account new field geological
data on brittle deformation near faults zones. The palaeostresses determined from the analysis of
microfaults and joints evidence NE-SW extension during the Tortonian, related to the development of
normal faults, and local NW-SE compression. During the Messinian, compression rotates clockwise to
the NNE-SSW and favors the sinistral strike-slip of the Carboneras Fault Zone, the dextral strike-slip of
minor NW-SE oriented faults and the development of large folds such as the Sierra Alhamilla antiform.
During the Pliocene, an anticlockwise rotation of stresses produces NNW-SSE oriented compression,
which contributes to fold development. These stresses favoured the sinistral activity of the Palomares
fault, with regard to Carboneras Fault.Finally, during the Quaternary an ENE-WSW extensional setting
and NNW-SSW to NW-SE compression predominate, and secondary NW-SE normal faults develop. Local
sinistral regime on Carboneras Fault may be consequence of the accommodation of the displacement of
NW-SE normal faults, making it act as a transfer fault. In addition, local NW-SE extension has been also
determined. NW-SE compression favoured the sinistral strike-slip activity of Palomares Fault regarding
the orthogonally oriented Carboneras Fault. The geological field and geomorphological data also confirm
the most intense recent activity of Palomares Fault zone, determining the orientation of the coast line.
This fault zone, extending to the north along the Arteal Fault, probably displaces Carboneras Fault
which shows only local evidences of recent sediment deformation and physiographic feature
displacements, typical of a relatively moderate activity.
Keywords: paleostress, palomares fault, recent tectonics