TEX86 Paleothermometer

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TEX86 Paleothermometer

• January 30, 2008
• Presented by Sanpisa Sritrairat

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Principles

• Marine Crenarchaeota - cren-are-KEY-o-tah
• Ubiquitous and abundant
• Archaea
• Membrane lipid
• composition depends
• on T

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Principles

• TetraEther indeX of 86-C atoms (TEX36)
• GDGTs (glycerol dibiphytanyl glycerol tetraether)
  membrane lipids variable cyclopopane rings
• GDGTI cold

4 regioisomer of 4 Marine Crenarchaeotas
GDGTs structures (Schouten et al., 2007)
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Calibration surface samples

• Schouten et al., 2002 Sampling sites
• 2 - 27C
• 20 35
• Oxicity variation

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Schouten et al., 2002
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• Crenarchaeol (GDGT1), higher 2-5 at high T
• GDGT0 not specific to marine plankton
• Too high conc. of GDGT4

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Schouten et al., 2002
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Schouten et al., 2002
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Culture Experiment
Relative Intensity
Retention Time
Wuchter et al., 2004
Schouten et al., 2007
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(No Transcript)
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Concentration of newly produced GDGTs
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Comparison with other proxies

• Pros
• vs. foram/carbornate no growth depth,
  dissolution, preserv., production, chem. problem
• vs. Isotope/inorg.chemical analysis Not require
  original seawater composition, water chemistry
  effects
• vs. alkenones comparable, but more abundance,
  unknown fxns of alk. in the algae, longer time
  scale
• Nutrients should not affect relative abundances

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Limitations

• Does not work where methane oxidation occurs
• Calibration for extreme temperature
• Crenarchaeotas habitat is not limited to surface
  water. Why strong correlation with SST?
• Long timer diagenesis?