HR: 11:20h
AN: PP42A-05    [Abstracts]
TI: The Development of TEX$_{86}$ for Continental Paleotemperature Construction
AU: * Werne, J P
EM: jwerne@d.umn.edu
AF: Large Lakes Observatory, University of Minnesota Duluth, 10 University Drive, Duluth, MN 55812 United States
AU: Powers, L A
EM: powe0285@d.umn.edu
AF: Large Lakes Observatory, University of Minnesota Duluth, 10 University Drive, Duluth, MN 55812 United States
AU: Johnson, T C
EM: tcj@d.umn.edu
AF: Large Lakes Observatory, University of Minnesota Duluth, 10 University Drive, Duluth, MN 55812 United States
AU: Hopmans, E C
EM: hopmans@nioz.nl
AF: Dept. of Marine Biogeochemistry & Toxicology, Royal Netherlands Institute for Sea Research, PO Box 59, Den Burg, 1790AB Netherlands
AU: Sinninghe Damste, J S
EM: damste@nioz.nl
AF: Dept. of Marine Biogeochemistry & Toxicology, Royal Netherlands Institute for Sea Research, PO Box 59, Den Burg, 1790AB Netherlands
AU: Schouten, S
EM: schouten@nioz.nl
AF: Dept. of Marine Biogeochemistry & Toxicology, Royal Netherlands Institute for Sea Research, PO Box 59, Den Burg, 1790AB Netherlands
AB: We have developed a new calibration for the TEX$_{86}$ paleotemperature proxy from a climatically diverse suite of globally distributed lacustrine systems (N=10). The results of this calibration show a strong linear relationship (r$^{2}$= 0.96) between TEX$_{86}$ values and published mean annual lake surface temperatures. The TEX$_{86}$ index as it currently stands appears to work only in large volume lakes, which are typically the best integrators of regional climate variability. The "marine" crenarchaeota responsible for producing the tetraether membrane lipids used in the TEX$_{86}$ index do not appear to be ubiquitous in lakes as previously thought, or are not in great enough abundance to be detected in the sediments of some, especially small, lakes. In contrast to the aquatically derived tetraether lipids, we have found terrestrial tetraether lipids in all lacustrine sediments analyzed thus far. The terrestrial tetraethers are primarily produced by soil bacteria and some methanogenic archaea. In very few cases the presence of terrestrial tetraethers, co-occurring with the aquatic tetraethers, confuse the TEX$_{86}$ signal and predict a colder than normal temperature. Here we explore the relationship between surface temperature and tetraether abundance, attempting to minimize the influence of the terrestrial tetraethers on the temperature signal. We can use the presence and abundance of these terrestrial tetraethers to examine climatic and landscape changes within the watershed. Here we present down-core tetraether data for temperature and landscape changes within the watershed of Elk Lake, MN, through the Holocene.
DE: 4808 Chemical tracers
DE: 3344 Paleoclimatology
DE: 1845 Limnology
DE: 1045 Low-temperature geochemistry
DE: 1615 Biogeochemical processes (4805)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting