La tectónica alpina en el SO peninsular (España)

Abstract

Alpine tectonics on the SO of the Iberian Peninsula develops two main family fault: NE-SW strike-slip left-handed faults and E-O to ENE-OSO thrusts located at the basins margins. Basins show a main E-O trend. A detailed study of clay mineral composition (<2 μm) in 229 samples collected in Coria, Cañaveral and Guadiana basin . The Lower Depositional Sequence (LDS) lies unconformable over basement rocks. Its mineralogical association is illit e(predominant)-kaolinit e-smectite. It has been found only in the Guadiana Basin, infilling small E-W grabens. Upper Depositional Sequence (UDS) forms widespread deposits lying over LDS or basement rocks. Its mineralogical association is smectite(predominant)-illite-kaolinit e. It should represent coalescingalluvial fans whose thickness decrease to the south. Tectonic activity begin and is more intense in the northern area, where conglomerates dominate; deformation migrates to the south and develop small basins filled with pre-existing sediments that evolve separately. Kaolinite is the clay mineral characteristic of the Culminating Unit. This unit is related to faults basins borders activity. E-O to NE faults control the drainage network. Main fluvial courses follow the basins main axis trend (~E-O) experiencing changes in their path when they found block-faulted uplifted and must deviate. This is the case of the Guadiana River when it arrives at the Messejana-Plasencia Fault old scarp.