Post-glacial evolution of alpine environments in the western Mediterranean region: The Laguna Seca record
Metadatos
Mostrar el registro completo del ítemAutor
López Avilés, Alejandro Jesús; Jiménez Moreno, Gonzalo; García-Alix Daroca, Antonio; García García, FernandoEditorial
Elsevier
Materia
Sedimentology Paleoenvironment Last deglaciation Holocene Alpine wetland Iberian Peninsula Climate change
Fecha
2022-01-18Referencia bibliográfica
Alejandro López-Avilés... [et al.]. Post-glacial evolution of alpine environments in the western Mediterranean region: The Laguna Seca record, CATENA, Volume 211, 2022, 106033, ISSN 0341-8162, [https://doi.org/10.1016/j.catena.2022.106033]
Patrocinador
Ministerio Ciencia e Innovacion/Agencia Estatal de Investigacion CGL201347038-R CGL2017-85415-R; Fondo Europeo de Desarrollo Regional "Una manera de hacer Europa" B-RNM-144-UGR18 P20_00059 RNM-190 MCIN/AEI BES2018-084293 RYC2015-18966 CGL2017-89618-R PID2019-1049449 GB-I00; FEDER "Una manera de hacer Europa"; Fundacion Seneca 20788/PI/18 RNM-178Resumen
In an effort to understand how alpine environments from the western Mediterranean region responded to climate
variations since the last glacial-interglacial transition, a detailed chronological control and sedimentological
analysis, supported by magnetic susceptibility, total organic carbon and C/N data, were carried out on the
sedimentary record of Laguna Seca (LS). This is a latitudinal and altitudinally (2259 masl) key alpine wetland site
located in the easternmost area of the Sierra Nevada, southern Iberian Peninsula, where sediments accumulated
during Heinrich Stadial 1, Bølling-Allerød (B-A) and the Younger Dryas (YD) - previously unrecorded in alpine
Sierra Nevada. Climate controlled sedimentation in LS and three coarse-grained and one fine-grained facies
association are differentiated, which help us decipher the paleoenvironmental evolution of LS: (1) subaerial
cohesionless debris flows during a paraglacial stage; (2) till or nival diamicton during a small glacier/nivation
hollow stage; (3) massive mudstone by suspension settling of clays into standing water during a lacustrine stage;
and (4) frost-shattering breccia deposited inside the lacustrine stage, probably during the YD, and linked to a
periglacial substage. The development of a previously existing small glacial cirque during the Last Glacial
Maximum (LGM) in the LS basin at an elevation between 2500 and 2300 m could be supported by the important
availability of slope sediments glacially-conditioned such as debris flows, reworked by paraglacial slope processes
during the first deglaciation stages, confirming previous studies of landforms in the catchment area and
the LGM-Equilibrium Line Altitude estimation above 2400 masl in Sierra Nevada. Mean sediment accumulation
rates in the LS sedimentary units (4.21 and 0.28 mm/yr during the paraglacial - small glacier/nivation stage and
the lacustrine stage, respectively) confirm that geomorphic activity accelerated just after glaciers retreated due to
a slope adjustment and high availability of glacially conditioned sediments. An abrupt change in paleoenvironmental
and paleoclimatic conditions occurred in LS at ~ 15.7 cal kyr BP. This change was probably due to an
increase in temperature and precipitation in the western Mediterranean region during the B-A. At LS, this
resulted in significant ice-melt, forming a deep-water lake in LS with important organic matter contribution until
the end of the Early Holocene (except in the YD when the lake level probably dropped), but elsewhere a general
glacier recession in the Sierra Nevada and an expansion of the Mediterranean forest in the southern Iberian
Peninsula. Finally, the general long-term aridification that occurred during the Middle Holocene until the present
in the western Mediterranean region triggered an important environmental change transforming LS into an
ephemeral wetland with an increase in aquatic productivity.