Estimación de la edad de las terrazas fluviales del río Yeltes (Salamanca) mediante cronofunciones

Abstract

This paper analyses the Quaternary geomorphological evolution of the Yeltes-Huebra River (together with the Águeda and the Tormes ones) are the main tributaries of the Duero downstream of the important topographic and hydrographic step cons- tituted by Los Arribes Canyon (c.450 m) around the Portuguese border. A detailed geomorphologic cartography of the Yeltes valley has been performed in the area in which this river dissects the Early Pleistocene Raña surface throughout the Ciudad Rodrigo Neogene Basin at a relative altitude of +102-105 m (Martín-Martín, 2019). This altitude coincides with the funda- mental erosion surface of the Iberian Massif, at +450-500 m downstream Los Arribes topographic step in the Portuguese Douro (Cunha et al., 2019). The chronological analysis applies the chronofunctions developed for Central Spain by Silva et al., (2017). This analysis indicates that the drainage network in the zone developed from 1.1 - 1.2 My and that exorheism began some 1.6-1.8 My ago, coinciding with the age of the Atlantic capture (c. 1.8 My) of the Duero basin recently proposed by Cunha et al. (2019) with data from the Portuguese area. The obtained chronological data indicate that terrace formation coincides in most cases with warm isotopic stages (OIS) or rather the transit from cold to warm stages, especially from OIS 9 (c. 300 ky) when the connectivity of the Atlantic-Duero drainage can be said to be effective.