5 research outputs found
Las fallas del recinto de la Alhambra : Faults in the Alhambra area
The Alhambra is built on a conglomeratic formation, known as the Alhambra Formation, whose age is Pliocene to Lower Pleistocene and has a visible thickness of 200 metres. The western part of the San Pedro escarpment corresponds to a fault-scarp with some retreat; the fault-plane outcrops in the innermost part of the escarpment, showing normal displacement and NW-SE strike with NE steep dip. This fault is the most important one of a set that outcrops along the northern hillslope of the Alhambra. Several topographic steps with NW-SE orientation are interpreted as retreated fault-scarps. In some cases, the activity of these faults seems to be very recent and maybe related to earthquakes. The seismic risk associated with these faults (and maybe some not-outcropping ones) can be taken to be moderate, as some historical damages have been reported concerning the Alhambra walls and the fence. In this respect, the Alhambra fence has numerous cracks geometrically related to fault planes outcropping in the Alhambra Formation, i.e. faults and cracks are continuous and have similar strike and dip. We hypothesize that these cracks are due to small displacements along the faults, occurred during recent earthquakes in the region. These faults constitute mechanical discontinuities, which represent a supplementary risk, because they contribute to reduce the stability of the entire rock massif
Exhumation constraints for the lower Nevado-Filabride Complex (Betic Cordillera, SE Spain) : a Raman thermometry and Tweequ multiequilibrium thermobarometry approach
Caracteristicas petrograficas y datacion U/Th de una calcreta laminar quaternaria: implicaciones de la captura de la cuenca de Guadix-Baza por el rio Guadalquivir
The Guadix topographic depression is a
Neogene-Quaternary basin located in the central
sector of the Betic Cordillera at the boundary
between the South Iberian margin and the Alboran
domain. This topographic depression is a plateau
with an average elevation of 1000 m in the
northern limb of the Sierra Nevada range. The
continental deposits infilling the Guadix basin
span time from the late Tortonian to the
Pleistocene, when a laminar calcrete developed on
fine to coarse-grained fluvial and lacustrine
deposits. Four coeval subsamples from the top
laminae of the calcrete were collected and dated
by the U/Th method. The resulting date is 42.6 ±
5.6 ka, which indicates the minimum age for the
cessation of active sedimentation in the Guadix
basin. We envisage the capture of the
Pliocene-Pleistocene endorheic Guadix basin by
the Guadalquivir River after 42 ka as the main
factor triggering the formation of the
present-day eroded landscape. After the capture,
the combination of climatic (wet periods),
lithological (soft and loose sediments), and
topographic (high average altitude) features
allowed the development of the present-day entrenched drainage patter