The challenging application of cosmogenic dating methods in residual glacial landforms: The case of Sierra Nevada (Spain)
Por:
Palacios D., Gómez-Ortiz A., Alcalá-Reygosa J., Andrés N., Oliva M., Tanarro L.M., Salvador-Franch F., Schimmelpfennig I., Fernández-Fernández J.M., Léanni L., ASTER Team
Publicada:
15 ene 2019
Categoría:
Earth-surface processes
Resumen:
An accurate review of the literature on surface exposure dating methods
shows evidence of the difficulty in applying cosmogenic dating methods
to old moraines because of the intensity of late Quaternary erosion
processes. Moreover, as in some previous cases, we also found special
difficulties in applying these methods to LIA moraines, caused by the
intensity of current paraglacial processes. The objective of this study
is to apply cosmogenic dating methods to very old and very young
moraines, which in both cases have been or are being affected
intensively by erosion. With this purpose, we collected samples of
boulders from moraines corresponding to (i) the penultimate glaciation
and (ii) the Little Ice Age (LIA), both from Sierra Nevada in the south
of the Iberian Peninsula. The sampling strategy was based on a
preliminary accurate analysis of the geomorphological settings of two
valley sites that resulted in the collection of only four boulder
samples from an old moraine and three more from a very recent moraine.
Using in situ-produced cosmogenic Be-10 to date these boulders, the old
samples yielded an age of ca. 130-135 ka for moraine stabilization. The
younger samples indicate that the LIA moraine accretion probably
occurred between the fourteenth and seventeenth centuries, with a
subsequent stage of accumulation during the nineteenth century as
suggested by historical documents. Dating a glaciation that occurred
prior to the last Pleistocene glacial cycle and dating LIA glacial
stages are novel in the context of Iberian glaciations and agree with
other palaeoenvironmental studies in Iberian and in other European
mountains. The limited number of boulders adequate for cosmic -ray
exposure dating prevents statistical methods to be applied, and
therefore highlights the need to improve geomorphological criteria in
sample selection. (C) 2018 Elsevier B.V. All rights reserved.
Filiaciones:
Univ Complutense Madrid, Dept Geog, Madrid, Spain
Univ Barcelona, Dept Geog, Barcelona, Spain
Univ Nacl Autonoma Mexico, Fac Filosofia & Letras, Mexico City, DF, Mexico
Aix Marseille Univ, CNRS, IRD, Coll France,UM CEREGE 34, Aix En Provence, France
Department of Geography, Universidad Complutense de Madrid, Madrid, Spain
Department of Geography, Universitat de Barcelona, Barcelona, Spain
Facultad de Filosofía y Letras, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
Aix-Marseille Université, CNRS, IRD, Coll. France, UM 34 CEREGE, Aix-en-Provence, France
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