The connections between river terraces and slope deposits as paleoclimate proxies: the Guadalaviar - Turia sequence (Eastern, Iberia Chain, Spain)

Abstract

This study, focused on the well-exposed terrace deposits of the Guadalaviar and Turia rivers and associated slopes, provides a better understanding of the genetic connection between river-terrace sediments and slope accumulations in a setting influenced by temperate to cold (extraglacial) climates: the Sierra de Albarracín and Alfambra–Teruel depression (Iberian Chain, eastern Spain). The terrace system comprises seven levels, Qt1 to Qt7. In the two older levels (Qt2 and Qt3) lateral connections with thick stratified slope screes were observed. The lower terraces (Qt4 to Qt7) have less expressive slope deposits. New Optically Stimulated Luminescence (OSL) ages, using quartz-OSL and pIRIR290, were obtained from these Quaternary deposits. Qt2 is dated ~310 to 270 ky (Marine Isotope Stage (MIS) 9–8); Qt3 dates from ~175 to 150 ky (MIS 6), Qt4 from ~136 to 80 ky (MIS 5e–a) and Qt5 from ~23 ky (MIS 2); Qt6 has a tufa dated to 10–4.6 ky (early–middle Holocene), while Qt7 probably records the last 4 ky (late Holocene). The thick slope deposits connected with the upper parts of the Qt2 and Qt3 terraces were generated under the cold-climate conditions of MIS 8 and MIS 6, respectively. These are the oldest dated slope deposits connected with fluvial terraces documented in the Mediterranean region, their preservation and recognition thus being of considerable significance. Chronological correlation of the glacial–interglacial cycles of the Pyrenees with the marine isotope stages conforms to the interpretation of paleo-environmental data and sedimentary controls of terrace genesis in extraglacial fluvial basins under temperate- to cold-climatic conditions.