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
JSS011 Poster presentation 2154
Folds evolution and basin development in the hinterland of an orogen: the
Almanzora neogene-quaternary corridor (SE Betic Cordillera, Spain)
Mr. Antonio Pedrera
Departamento de Geodinamica Universidad de Granada
Jess Galindo-Zaldvar, Ana Ruz-Constn, Carlos Duque-Calvache, Ngel Carlos Lpez-
Garrido, Carlos Marn-Lechado, Carlos Sanz De Galdeano, Inmaculada Serrano
The Almanzora Corridor is an E-W elongated depression located on the internal zones of the Betic
Cordillera. Its growth is associated with a complex structural interaction dominated by folding and
related faulting, developed in a changing stress scenario. (a) During the Early Tortonian, a N-S directed
compression is associated to the northwards propagation of deformation, with progressive folds growth,
first starting in Sierra de Los Filabres antiform and then, in Sierra de Las Estancias antiform. (b) Later,
since Tortonian, an anticlock-wise rotation in stress field occurred, the shortening direction changed to
NW-SE with an orthogonal associated extension. Therefore, the maximum stress axis became oblique to
the previous E-W oriented Sierra de Los Filabres fold producing dextral shear deformation along a wide
band located along the corridor and Sierra de las Estancias. Geophysical data (2D gravity models, 2D
MT images, hypocenter distribution and earthquake focal mechanism solutions) show the presence of
large low-angle crustal detachments that allow the folds growth in their hanging walls since the
Tortonian. The main outcropping active faults are NW-SE and E-W normal faults. The crustal thickening
process is still active in the Central Betic. Both the low and high-angle faults, active in a variable stress
field, are the responsible of the present-day seismicity of the region pointing the need of the crustal
studies to characterize the seismic hazard.
Keywords: paleostress evolution, fault overprinting, fault related fold