Download - Organics at 40 o S (D357)
Organics at 40o S (D357)
Maite Hernández/Rich Pancost
PHYTOPLANKTON BIOMARKERS
O
C37-C39 Ethyl and methyl ketones: Alkenones
Brassicasterol
OH
24-methylcholesta-5,24(28)-dien-3β-ol
OH cholesta-5,22-dien-3β-ol
24-ethylcholesta-5,24(28)-dien-3β-olOH
OH
24-propylcholesta-5,24(28)-dien-3β-ol
Prasinophyceae
Crysophyceae
OH
24-methylcholesta-5,22-dien-3b-ol
Source organism
Preserved
+ =
Paleo proxy calibration
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
Longitude (˚E)
−45˚
−40˚
−35˚
−30˚
−25˚
St 1St 3
St 6
St 8
St 11
St 13
−10˚ 0˚ 10˚ 20˚
Latit
ude
( ˚S)
−8000
−6000
−4000
−2000
0Depht (m)
SBiomarker distributions inSurface waters
Longitude (˚E)
−45˚
−40˚
−35˚
−30˚
−25˚
St 1St 3
St 6 St 11
−10˚ 0˚ 10˚ 20˚
Latit
ude
(S̊
)
−8000
−6000
−4000
−2000
0Depht (m
Biomarker distributions indeep waters
Longitude (˚E)
−45˚
−40˚
−35˚
−30˚
−25˚
St 1St 3
St 6
St 8
St 11
St 13
−10˚ 0˚ 10˚ 20˚
Latit
ude
( ˚S)
−8000
−6000
−4000
−2000
0Depht (m)
SBiomarker distributions inSurface sediments
Why so different?
Seasonal bias
Degradation
- Hardman-Mounford et al. (2003) chl-a data: weak seasonality at St. 6 and St. 11
Longitude (˚E)
−45˚
−40˚
−35˚
−30˚
−25˚
St 1St 3
St 6
St 8
St 11
St 13
−10˚ 0˚ 10˚ 20˚
Latit
ude
( ˚S)
−8000
−6000
−4000
−2000
0Depht (m)
S
Vertical Fluxes
230Thxs
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 [O2] 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 TEX86 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!