Volcanic, tectonic and climate controls on lacustrine sedimentary supplies over the last millenia in NE Chilean Patagonia (Lake Esponja, Aysen, 45°S)

Fagel, Nathalie; Pedreros, Pablo; ALVAREZ-SANHUEZA, DENISSE BALBINA; Israde Alcantara, Isabel; Alcantara, Isabel Israde; Vega Alay, Ignacio; Alay, Ignacio Vega; Namur, O.; ARANEDA-CASTILLO, ALBERTO EDUARDO; Schmidt, Sabine; Lepoint, Gilles; URRUTIA-PEREZ, ROBERTO ENRIQUE

Abstract

The environmental variability of Northern Chilean Patagonia during the last millennia is evaluated using a multi-proxy analysis of sediment cores from Lake Esponja (45 degrees S 72 degrees W) to decipher if the sediment deposition is controlled by volcanic eruptions, landslides induced by earthquake or heavy rainfall. The lake is located in a glacio-tectonic valley in Patagonia. The organic-rich clayey silt sediment with low biogenic silica content was analysed for grain size, magnetic susceptibility, organic matter, biogenic silica content and diatom assemblages, mineralogy (X-ray diffraction), organic (IRMS C and N analyses) and inorganic (XRF core-scanner) geochemistry and glass shard major composition (Microprobe, SEM). The combination of Pb-210, Cs-137, C-14 and tephrochronology indicates an averaged accumulation rate of 0.4 mm/year, leading to a record of similar to 3.5 kyr within 154 cm. The sedimentary geochemistry records changes in volcanic supplies, diatom productivity and detrital inputs. The sediments were interrupted by millimetric to centimetric layers corresponding to tephra deposition related to explosive eruptions of nearby volcanoes Maca, Melimoyu and Hudson. Concerning the diatoms, the dominant planktonic species (80-150 cm) are replaced by benthic species in a transition interval (55-80 cm) and then by Surirella spp. in the upper core. This last genus indicates a closure of the basin similar to 2 ka ago, probably related to an uplift linked to a rejuvenation of the Manihuales fault. This local change could reflect regional tectonic instability. Indeed, a partial earthquake rupture occurred around similar to AD100 along the southern part of the Valdivia segment, recorded as a mass transport deposit in Aysen fjord sedimentation. The fine detrital input varies over time with more variable Si/Al values in the lower part of the LEs14 core than in the upper 80 cm. The higher values may reflect wetter conditions, leading to an higher lake level and more turbid conditions in agreement with changes in diatom assemblages.

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Título según WOS: Volcanic, tectonic and climate controls on lacustrine sedimentary supplies over the last millenia in NE Chilean Patagonia (Lake Esponja, Aysen, 45°S)
Título según SCOPUS: ID SCOPUS_ID:85148064943 Not found in local SCOPUS DB
Título de la Revista: HOLOCENE
Volumen: 33
Editorial: SAGE PUBLICATIONS LTD
Fecha de publicación: 2023
Página de inicio: 518
Página final: 535
DOI:

10.1177/09596836231151828

Notas: ISI, SCOPUS