Unraveling paraglacial activity on Sierra de Gredos, Central Spain: A study based on geomorphic markers, stratigraphy and OSL

Esperanza Muñoz-Salinas*, Miguel Castillo, David Sanderson, Tim Kinnaird

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    Abstract

    We study the paraglacial activity in Gredos Gorge, a glaciated valley of Sierra de Gredos (Central Spain), using geomorphic markers, stratigraphy and an approach based on OSL. We use luminescence signals from debris flow and fluvial deposits as well as OSL dating of three deposits to detect the main paraglacial processes in Gredos Gorge. We identify two major phases of paraglacial activity during and after the retreat of Last Glacial Maximum (LGM) glaciers. The first phase consisted of high discharge debris flows, sourced up-valley, triggered during the deglaciation. The second phase started ~. 11. ka and is characterized by two processes: (1) the triggering of low discharge debris flows sourced on the flanks of moraines, and (2) the reworking of paraglacial deposits by rivers. Our results of OSL signals, stratigraphy markers and sediment volume indicate that during and after the deglaciation of Gredos Gorge, paraglacial sediment was depleted as theory predicts. However, glacigenic sediments have not been transferred to sediment sinks as long as ~. 70% of glacial deposits are still stored in the valley. The transition of the environmental conditions prevailing during the LGM to current Mediterranean climate seems to play an important role in delaying the exhaustion model of glacially-conditioned sediment release. We propose that the poor coverage of vegetation driven by the Mediterranean climate prevents the stabilization of glacigenic sediment that is only mobilized during high discharge events responding to extreme rainfalls.

    Original languageEnglish
    Pages (from-to)207-214
    Number of pages8
    JournalCatena
    Volume110
    DOIs
    Publication statusPublished - Nov 2013

    Keywords

    • Debris flow activity
    • Mediterranean climate
    • OSL
    • Paraglacial sediment release
    • Sierra de Gredos
    • Stratigraphy

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