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

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Publication date 2011
Author Moy CM, Dunbar RB, Guilderson TP, Waldmann N, Mucciarone DA, Recasens C, Ariztegui D, Austin JA, Anselmetti FS,
Project Potrok Aike Maar Lake Sediments Archive Drilling Project - The Swiss contribution (PASADO-CH). Phase II
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Original article (peer-reviewed)

Journal EARTH AND PLANETARY SCIENCE LETTERS
Volume (Issue) 302(1-2)
Page(s) 1 - 13
Title of proceedings EARTH AND PLANETARY SCIENCE LETTERS
DOI 10.1016/j.epsl.2010.11.011

Abstract

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 fromLago Fagnano, a large lake in southern Tierradel 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 8000 yr based on pollen concentrates, thereby avoiding contamination frombedrock derived lignite. Our chronology is consistentwith a tephrochronologic age date for deposits fromthemiddleHolocene VolcánHudson eruption. Combining bulk organic isotopic (!13C and !15N) 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-termtrends in C/N ratio, carbon accumulation rate, and magnetic susceptibility re!ect an overall Holocene increase in the delivery of terrestrial organic and lithogenicmaterial to the deep eastern basin.We attribute this variability towesterly wind derived precipitation. Increasedwind 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 !ow events in the record. We identify an increase in bulk !13C between 7000 and 5000 cal yr BP that we attribute to enhanced aquatic productivity driven by warmer summer temperatures. The Lago Fagnano !13C record shows similarities with Holocene records of sea surface temperature fromthemid-latitude Chilean continental shelf and Antarctic air temperatures from the Taylor Dome ice core record in East Antarctica. Mid-Holocene warming occurred simultaneously across the Antarctic Frontal Zone, and in particular, in locations currently in!uenced by the Antarctic Circumpolar Current.
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