In April 2011 we started on a field trip to investigate the Padul-Nigüelas Fault Zone in Spain (+/- 37°N, 3°36°W, see map here). Like the Wednesday Centerfault (5), the PNFZ is in the Granada Basin but some 40 km ENE. Delimiting Tortonian to Quaternary basin fillings to the Sierra Nevada, the PNFZ forms hardrock scarps.
Widely known for seismic activity, we used geophysics (Ground Penetrating Radar, Geoelectrics) as well as classical geological methods to examine where we can find active faults.
The landscape clearly indicates neotectonic activity by features like triangular facets and deeply incised channels and significant scarps. Alfaro (2001) characterized the hard rock scarp as inactive – and so did we. Exhumed by erosion rather than fault activity we consider a basinwards movement of the fault activity. Focusing on the alluvium and the colluvial wedges of the basement scarp, we encountered fossilized and active faults and even a scarp in the poorly consolidated rock. GPR will help us to understand subsurface geometries and to calculate offsets even in the non-outcropping parts.
Two Master’s theses are running, so during this summer we might get some nice results.
See you in Corinth!
Alfaro, P., J. Galindo-Zaldívar, A. Jabaloy, A.C. Lopez Garrido, C. Sanz de Galdeano (2001). Evidence for the activity and paleoseismicity of the Padul fault (Betic Cordillera, southern Spain), Acta Geologica Hispanica 36 (3-4), 283-295.
Galindo-Zaldívar, J., A.J. Gil, M.J. Borque, F. González-Lodeiro, A. Jabaloy, C. Marín-Lechado, P. Ruano, C. Sanz de Galdeano (2003). Active faulting in the internal zones of the central Betic Cordilleras (SE, Spain). Jorunal of Geodynamics 36, 239-250.
Hamdouni, R., Irigaray, C., Fernández, T., Chacón, J., Keller, E.A. (2008). Assessment of relative active tectonics, southwest border of the Sierra Nevada (southern Spain). Geomorphology 96, 150-173.
Reicherter, K.R. (2001). Paleoseismologic advances in the Granada basin (Betic Cordilleras, southern Spain). Acta Geologica Hispanica 36 (3-4), 267-281.
Reicherter, K., G. Peters (2005). Neotectonic evolution of the Central Betic Cordilleras (Southern Spain). Tectonophysics 405,191-212.