Seismic stratigraphy of Lago Fagnano sediments (Tierra del Fuego, Argentina) - A potencial archive of paleoclimatic change and tectonic activity since the Late Glacial
Waldmann, David Nicolas (University of Geneva. Section of Earth Sciences)
Ariztegui, Daniel (University of Geneva. Section of Earth Sciences)
Anselmetti, Flavio Stefano (ETH-Zürich. Geological Institute)
Austin, James Albert Jr. (University of Texas at Austin. Institute for Geophysics, John A. and Katherine G. Jackson School of Geosciences,)
Dunbar, Robert B.
Moy, Christopher M.
Recasens, Cristina (University of Geneva. Section of Earth Sciences)

Data: 2008
Resum: Located at 54ºS in the heart of the Island of Tierra del Fuego, Lago Fagnano occupies the deepest of a chain of en-echelon tectonic depressions along the Magallanes-Fagnano Transform system (MFT). A recent geophysical campaign combining 3. 5 kHz (pinger) single-channel with 1 in3 airgun multi-channel systems surveyed more than 100 m of glacio-lacustrine sediments filling two main sub-basins. These data provide a unique opportunity to visualize the most recent lacustrine sequence with high-resolution while simultaneously imaging the oldest infill. A preliminary seismic stratigraphic analysis of the high-resolution 3. 5 kHz pinger data allowed the identification of three major seismostratigraphic units (A, the oldest and C, the youngest). While unit A is interpreted as glacially derived sediments, the overlying unit B is interpreted as fining upward sequences of proglacial turbidites reflecting sediment pulses released by the retreating Fagnano glacier during the last deglaciation. A major environmental change occurred during deposition of unit C when pelagic style of sedimentation is intercalated by sequences of downslope mass flow events probably triggered by relatively strong tectonic pulses along the MFT system. Gravity cores show a regular alternation of light and dark laminae occasionally interrupted by homogenous sedimentary units interpreted as turbidites. Ultra-high resolution X-ray fluorescence micro-profiles show fluctuations in major trace elements at mm scale that may indicate seasonal variations in the sedimentary influx. These core data provide a unique record of decadal changes in regional climate that can be compared with other marine and continental archives to improve our understanding of the forcing mechanisms behind climate change.
Drets: Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l’obra i la creació d’obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l’obra original i es reconegui l’autoria de l’obra original. Creative Commons
Llengua: Anglès.
Document: article ; recerca ; publishedVersion
Matèria: Paleoseismology ; Lacustrine sedimentation ; Turbidites ; Paleocliamte
Publicat a: Geologica acta, Vol. 6, Núm. 1 (Març 2008) , p. 101-110, ISSN 1696-5728

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DOI: 10.1344/105.000000244

10 p, 2.9 MB

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