Interpretación paleoclimàtica de las varvas pliocenas de la Cuenca de Villarroya (Sierra de Cameros, La Rioja)

• Main Authors: Muñoz Jiménez, Arsenio, Sánchez Valverde, B.
• Format: Article in Journal/Newspaper
• Language: Spanish
• Published: Sociedad Geológica de España 2001
• Subjects: Pliocene; Varves; Sunspot; El Niño/Southern Oscillation (ENSO); North-Atlantic Oscillation (NAO); Quasi-biennial Oscillation (QBO); North Atlantic; North Atlantic oscillation
• Online Access: http://hdl.handle.net/10272/9580

This is a study of an extremely good outcrop of 1745 varves in the Villarroya Pliocene Basin (Spain). We have used the periodogram approach for estimating power spectra and periodicities of about 1 2, 6-7 and 2-3 years have been obtained. The light layers of the varves record the run-off of gastropods, ostracods and charophytes from seasonal productivity cycle, and are generated during late summer and autumn. It seems clear that the climatic information provided by these cycles corresponds mainly to summer time, which would be translated into a variation of the light layer thickness due to a more or less, intense development of the flora and fauna, being thicker in years of higher temperatures and thinner in years of lower temperatures. Considering the results, we would suggest that the sedimentation of these materials in the Pliocene was driven by solar activity or/and ENSO, NAO, and QBO phenomena. Nowadays these phenomena produce rainfall and temperature changes with the cyclicities shown In this study and we think they could have operated in the same way in Pliocene times