Unraveling paraglacial activity on Sierra de Gredos, Central Spain: A study based on geomorphic markers, stratigraphy and OSL
Por:
Munoz-Salinas, E, Castillo, M, Sanderson, D, Kinnaird, T
Publicada:
1 nov 2013
Categoría:
Earth-Surface Processes
Resumen:
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 similar to 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 similar to 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. (c) 2013 Elsevier B.V.
All rights reserved.
Filiaciones:
Munoz-Salinas, E:
Univ Nacl Autonoma Mexico, Dept Reg Geol, Inst Geol, Mexico City, DF, Mexico
Castillo, M:
Univ Nacl Autonoma Mexico, Dept Reg Geol, Inst Geol, Mexico City, DF, Mexico
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