Organics at 40 o S D 357 Maite
- Slides: 16
Organics at 40 o S (D 357) Maite Hernández/Rich Pancost
PHYTOPLANKTON BIOMARKERS C 37 -C 39 Ethyl and methyl ketones: Alkenones Brassicasterol cholesta-5, 22 -dien-3β-ol Prasinophyceae 24 -ethylcholesta-5, 24(28)-dien-3β-ol 24 -methylcholesta-5, 24(28)-dien 3β-ol 24 -propylcholesta-5, 24(28)-dien-3β-ol Crysophyceae
Paleo proxy calibration Source organism + Preserved = Paleo Proxy
Is PP reflected in underlying sediments? • Lipid distributions reflect productivity variations (Lee and Wakeham, 1988; Hernández-Sánchez et al. , 2010). Coccolithophorids Diatoms Alkenones Sterols
Paleo proxy calibration • Is PP reflected in underlying sediments? : Potential for community assemblage proxy Source organism + Preserved = Paleo Proxy
Biomarker distributions in Surface waters
Biomarker distributions in deep waters
Biomarker distributions in Surface sediments
Why so different? Seasonal bias - Hardman-Mounford et al. (2003) chla data: weak seasonality at St. 6 and St. 11 Degradation
Vertical Fluxes 230 Th xs
Summary - Biomarker distributions in upper water column suggests homogeneous productivity - Distributions strikingly different in sediments - Most degradation occurs throughout the water column and/or sediment-water interface - Alkenones, hydroxy methyl alkanoates and diols seem to be the most diagenetically stable. - Subtle differences in [O 2] seem to have an effect on preservation
To do … • Biomarker distributions represent community structure in surface waters. – Heather Bounman and Tom • Estimate vertical fluxes. – Gideon Henderson and Alex Thomas
Paleo proxy calibration • Is PP reflected in underlying sediments? : - Hernandez-Sanchez et al. (Pancost, Henderson, Homoky, Bounman, Thomas +). GCA? • GDGT distributions in the water column: Implications for the TEX 86 paleothermometry proxy - Hernandez-Sanchez, M. T. , Woodward, M. , Taylor, K. W. , Henderson, G. , Pancost, R. D. , GDGT distributions in SE Atlantic sediments match those in subsurface waters: Geology (to be submitted)
Other outcomes • Hernandez-Sanchez, M. T. , and Pancost, R. D. Occurrence of 1 -O-monoalkyl glycerol ether lipids in both marine waters and sediments (in prep. )
Thanks for your attention!
