Las superficies de erosión neógenas en la zona de transición entre la Cordillera Ibérica y el Sistema Central(Guadalajara, España)

Abstract

The geomorphological mapping in the transition zone between the Central System and the Iberian Chain has allowed us to identify four planation surfaces, commons in both orogens. The genesis of these surfaces is closely related to the Cenozoic sedimentary units of the Madrid Basin, specially to the piedmont systems located in Central System margin. The oldest surface, or SE1, is located at the same morphological level that a little outcrop of gravels and blocks, burying a weathering mantle developed in gneisses. The second planation surface (SE2), forms parameras in the Iberian Chain and pediments in the Central System, connecting with a well-preserved glacis developed on piedmont deposits older than Turolian sediments (Upper Neogene Unit). Consequently, this surface is related to the Intermediate Unit, probably with Upper Aragonian sediments, previous to the deformation processes which caused NE-SO antiforms and synforms in the surface (Guadarrama direction). The third surface is deformed in lesser degree and shows a closely association with Upper Turolian sediments. However, the current morphology of the surface is associated with a glacis (La Mierla Surface, 1046 m asl), whose deposits are overlying Upper Turolian sediments and which are probably equivalents to the development of the Páramo erosional surface during the Upper-Turolian-Ruscinian. The youngest planation surface consist mainly of facets preserved in the slope valleys and connects with a four glacis of Pliocene age, which is located over the first fluvial terraces.