TY - JOUR
T1 - Unraveling paraglacial activity on Sierra de Gredos, Central Spain
T2 - A study based on geomorphic markers, stratigraphy and OSL
AU - Muñoz-Salinas, Esperanza
AU - Castillo, Miguel
AU - Sanderson, David
AU - Kinnaird, Tim
PY - 2013/11
Y1 - 2013/11
N2 - 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.
AB - 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.
KW - Debris flow activity
KW - Mediterranean climate
KW - OSL
KW - Paraglacial sediment release
KW - Sierra de Gredos
KW - Stratigraphy
UR - http://www.scopus.com/inward/record.url?scp=84880826322&partnerID=8YFLogxK
U2 - 10.1016/j.catena.2013.06.018
DO - 10.1016/j.catena.2013.06.018
M3 - Article
AN - SCOPUS:84880826322
SN - 0341-8162
VL - 110
SP - 207
EP - 214
JO - Catena
JF - Catena
ER -