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Technischen Universitat Munchen (2005)

Sediment dynamics in Lago Calafquén and Lago Villarrica (Northern Patagonia - Chile)

Volland, Sabine

Titre : Sediment dynamics in Lago Calafquén and Lago Villarrica (Northern Patagonia - Chile)

Sediment Dynamik in den Seen Lago Calafquén und Lago Villarrica (Nord-Patagonien - Chile)

Auteur : Volland, Sabine

Université de soutenance : Technischen Universitat Munchen

Grade : Doktors der Naturwissenschaften (Dr. rer. nat.) 2005

Résumé
On Lago Calafquén and Lago Villarrica (Northern Patagonia, south-central Chile) sediment-geological and -biological studies as well as high-resolution seismic investigation of the lake basins were carried out in order to provide a baseline study on spatial and time-related sedimentation processes. Both lakes are located in an active volcanic and tectonic setting that is subject to frequent and large earthquake activity. Evidences are given in the high-resolution seismic mapping of large mass movements and large-scale soft sediment deformation structures in the lake bottom sediments. Sediment texture analysis of the lake surface sediments reflect the interaction of the lakes with their catchment and size and allow to distinguish catastrophic events from natural seasonal drainage. Mapping of the sediment textural patterns trace the pathways of different currents and effects of geodynamic activity on sedimentation processes in the lake basins. Multi-proxy studies on short sediment cores characterize chronological sedimentation processes and track possible environmental changes during the last 3000 and 1200 years, respectively. Frequent volcanic activity interrupts this normal lacustrine sedimentation by clastic tephra layers. Both lakes show different response to changes of the local catchment but possibly reveal a regional spanning common large-scale trend in biogenic productivity between AD 800 and AD 1500. Diatom assemblage investigation on Lago Calafquén and Lago Villarrica show particularly low species. The frequent volcanic impact does not expose any changes in diatom abundance but only shifts in the relative abundance, as observed by layers of monospecific diatom assemblages. Observations in the variance of the diatom species lead to the interpretation of possible environmental responses, e.g. possible turbulence and up-welling in Lago Calafquén during BC 50 to AD 1350, and the onset of permanent settlement around Lago Villarrica by the 18th/beginning of 19th Century.

Mots clés  : Sedimentology, Palaeolimnology, Palaeoclimate, climate and environmental archive, environmental change, diatoms, seismic stratigraphy, sediment texture, multi-proxy — Sedimentologie, Paläolimnology, Paläoklima, Klima- und Umweltarchiv, Umweltveränderungen, Diatomeen, seismische Stratigraphie, Sedimenttextur, Multi-proxy

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Page publiée le 26 janvier 2016, mise à jour le 10 janvier 2019