Geomorphological and Geochronological Analysis Applied to the Quaternary Landscape Evolution of the Yeltes River (Salamanca, Spain)

Iván Martín-Martín,Antonio Martínez-Graña,Javier Elez,Pablo-Gabriel Silva

doi:10.3390/su12197869

Abstract

This paper aims to study the Quaternary geomorphological evolution of the Yeltes river-valley (Duero Basin, Central Spain) primarily based on the study of the Late Neogene piedmont dissected by the river and its Quaternary terrace sequence, since fluvial terraces are excellent archives to study the landscape and climate evolution during this period. Detailed geomorphological mapping implemented in GIS-based digital elevation models was used to the further applications of existing fluvial chronofunctions (relative terrace height-age transfer functions) to establish a numerical geochronology to the sequence of fluvial terraces in the zone. The obtained theoretical ages points to an onset of fluvial incision in the zone after 2.0–2.5 Myr ago, with the dissection of the “Raña surface” (a Gelasian alluvial piedmont widely developed in Central Spain). The obtained terrace ages coincide, in most cases, with warm isotopic stages (MIS) or mainly with the transit of cold to warm MIS. Additionally, this study suggests that the full connectivity of the Yeltes drainage (Ciudad Rodrigo Basin) with the Atlantic drainage was not completely effective until MIS 9 (c. 0.29 Myr). The new reported data allows for the exploration of the timing and processes involved in the capture of inland sedimentary basins (Ciudad Rodrigo, Duero basins) by the Atlantic drainage during the early Quaternary.

Highlights

During the last million years, the Cenozoic basins in the center of the Iberian Peninsula opened to the Atlantic, produced the so-called Atlantic Capture [1]
The Yeltes River is located on the border between the northern plateau (Meseta norte) and the beginning of the mountainous relief of the Central System, linking the relief of the Sierra de Francia range with the Paleogene and Neogene filling of the Ciudad Rodrigo Basin
Cenozoic sedimentation was defined by the so-called arkosic (Paleogene) and post-arkosic (Neogene) cycles defined for this area, constituted by materials derived from the erosion of granitic materials of the southern reliefs [18]

Summary

Introduction

During the last million years, the Cenozoic basins in the center of the Iberian Peninsula opened to the Atlantic, produced the so-called Atlantic Capture [1]. This process represented the present drainage network development and this region’s landscape modeling, through the dissection of the Plio-Quarternary alluvial piedmont known as the “Raña surface” in central Spain [2,3,4,5,6,7]. The river terraces are excellent archives on the relationships of landscape evolution and climate during the Quaternary [8,9,10] They record low-frequency climatic changes of astronomical origin, and climatic fluctuations correlated with marine isotopic stratigraphy [11]. This work deals with the geomorphological analysis and evolution of the Sustainability 2020, 12, 7869; doi:10.3390/su12197869 www.mdpi.com/journal/sustainability that constitutes the “Raña” piedmont, where the altitude decreases from 1000 m in the range front to

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