A geochemical and sedimentary record of high southern latitude Holocene climate evolution from Lago Fagnano, Tierra del Fuego

• Published in: Earth and Planetary Science Letters
• Main Authors: Moy, Christopher M., Dunbar, Robert B., Guilderson, Thomas P., Waldmann, Nicolas, Mucciarone, David A., Recasens, Cristina, Ariztegui, Daniel, Austin Jr., James A., Anselmetti, Flavio S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2011
• Subjects: Southern Hemisphere westerly winds; Holocene paleoclimate; radiocarbon; stable isotopes; Tierra del Fuego; Antarc*; Antarctic
• Online Access: https://doi.org/10.1016/j.epsl.2010.11.011

Situated at the southern margin of the hemispheric westerly wind belt and immediately north of the Antarctic Polar Frontal zone, Tierra del Fuego is well-positioned to monitor coupled changes in the ocean-atmosphere system of the high southern latitudes. Here we describe a Holocene paleoclimate record from sediment cores obtained from Lago Fagnano, a large lake in southern Tierra del Fuego at 55°S, to investigate past changes in climate related to these two important features of the global climate system. We use an AMS radiocarbon chronology for the last 8000yr based on pollen concentrates, thereby avoiding contamination from bedrock-derived lignite. Our chronology is consistent with a tephrochronologic age date for deposits from the middle Holocene Volcán Hudson eruption. Combining bulk organic isotopic (δ 13 C and δ 15 N) and elemental (C and N) parameters with physical sediment properties allows us to better understand sediment provenance and transport mechanisms and to interpret Holocene climate and tectonic change during the last 8000 yr. Co-variability and long-term trends in C/N ratio, carbon accumulation rate, and magnetic susceptibility reflect an overall Holocene increase in the delivery of terrestrial organic and lithogenic material to the deep eastern basin. We attribute this variability to westerly wind-derived precipitation. Increased wind strength and precipitation in the late Holocene drives the Nothofagus forest eastward and enhances run-off and terrigenous inputs to the lake. Superimposed on the long-term trend are a series of abrupt 9 negative departures in C/N ratio, which constrain the presence of seismically-driven mass flow events in the record. We identify an increase in bulk δ 13 C between 7000 and 5000 cal yr BP that we attribute to enhanced aquatic productivity driven by warmer summer temperatures. The Lago Fagnano δ 13 C record shows similarities with Holocene records of sea surface temperature from the mid-latitude Chilean continental shelf and Antarctic air temperatures from the ...