1. Interpreting the sedimentary record
I Distributions represent processes
Physical (temperature, salinity, density)
Chemical (nutrients, recycled and scavenged elements)
II Identify faithful recorders (proxies)
Sediment chemistry, microfossil type, shell chemistry
III Interpretation
Reconstruct distributions
Infer paleo-processes
IV Ground-truth / calibration:
Modern oceanographic processes
Modern sea-floor sediments (core tops)

2. May reflect more than one process, more than one path.
Distributions
May reflect more than one process, more than one path.
Recorders
What do the proxies record? Where? When?
(property) (depth habitat) (seasonality)
Reconstruction
Spatial distribution of paleo data (point, transect, map, 3D)
Chronology -- Time slice -- Time series.
Interpretation
Is the present the key to the past?
Distribution ≠ rate

3. Bio-limiting, bio-intermediate, and bio-unlimited elements

4. Conservative
Invariant with depth.
Pacific = Atlantic
Recycled
Increase downward.
Pacific > Atlantic
Scavenged
Decrease downward.
Pacific < Atlantic

5. Sea-surface temperature
Examples:
Sea-surface temperature
Calcium-carbonate accumulation
Deep-ocean circulation

6. Sea-surface temperature (SST)

7. CLIMAP SST
Reconstruction of
past sea-surface
temperatures using
statistical (multi-
variate) approach to
analyzing microfossil
assemblages. In this
case, planktonic
foraminifera shells.

8. Faunal assemblages
Microfossils reflect
the predominant
planktonic species at
a given location. A
handful dominate in
the tropics.

9. Faunal assemblages
A second assemblage
occurs primarily in
the subtropics.

10. Faunal assemblages
Another assemblage
occupies the subpolar
regions.

11. Faunal assemblages
A single species
of foraminifera is
predominant in
polar regions.

12. Faunal assemblages
Observations can be
combined to draw
inferences about past
environments.
CLIMAP used a
multi-variate
statistical approach.

13. Transfer functions
The assemblage data,
combined as factors,
provide a regression
with variables such
as SST. Predictions
based on these
relationships can be
tested against other
datasets to evaluate the
success of the method.

14. CLIMAP SST
Strong cooling
at high latitudes
and little change
in the tropics.
Modern
LGM

15. CaCO3 accumulation and evidence for lysocline changes
Cores from eastern equatorial Pacific display variations in CaCO3,
suggesting repeated shoaling and deepening of dissolution horizon.
Core
depths

16. Did the CaCO3 saturation horizon (lysocline) shift at the LGM?

17. Higher at LGM in the Pacific. Lower at LGM in other oceans.
CaCO3 content
Higher at LGM in the Pacific.
Lower at LGM in other oceans.
ATL
IND
SOU
PAC

18. CaCO3 flux
Regional estimates
of CaCO3 mass
accumulation rates.

19. CaCO3 flux
Global sum = little change.
Holocene slightly higher.
Does flux = lysocline?

20. Ocean circulation
Evident in many physical properties.
Proxies utilize influence of biology.
Biological pump
Vertical flux of organic matter and
hard parts from surface to the deep sea.
Superimposed on deep ocean circulation.

21. Evident in salinity and many other properties…
The meridional overturning circulation (MOC) produces North Atlantic Deep Water (NADW).
NADW
GEOSECS
Evident in salinity and many other properties…

22. Biological pump
Surface productivity
utilizes nutrients and
carbon. Gravity moves
them to the deep-sea,
and respiration returns
them to the seawater.

23. Vertical rain of carbon is highest near the surface
Carbon fluxes
Vertical rain of carbon is
highest near the surface
and declines with depth,
Indicating remineralization
within the water column.
(Data from N. Pacific
sediment traps)
Martin et al. (1987)

24. Productivity
Biological activity results
in systematic changes in
concentration and isotopic
ratio of bio-limiting and
bio-intermediate elements.

25. Nutrients as tracers
Nutrients at depth are
swept “downstream”
by the global ocean
circulation.

26. SST, density,
and nutrients
High latitude surface
waters in the north
are nutrient-depleted.
waters in the south
are nutrient-rich.
Deep-waters formed
at the two poles
display strong
chemical contrast.

27. Surface water O2
Surface waters
(over) saturated due
to bubble injection
and photosynthesis.

28. Deep water O2
Deep waters become
depleted due to
respiration along the
circulation pathway.

29. Deep water O2
Apparent oxygen
utilization reveals
the pattern of deep
ocean circulation.

30. Carbon isotopes
Photosynthetic fractionation
of organic carbon leaves
seawater enriched in heavier
carbon-13. The resulting
Isotopic ratio in seawater is
then incorporated in CaCO3,
providing a nutrient-tracer.

31. Evident in salinity and many other properties…
The meridional overturning circulation (MOC) produces North Atlantic Deep Water (NADW).
NADW
GEOSECS
Evident in salinity and many other properties…

32. Also evident in carbon isotopes (d13C).
The meridional overturning circulation (MOC) produces North Atlantic Deep Water (NADW).
NADW
Kroopnick (1985)
Also evident in carbon isotopes (d13C).

33. LGM meridional section, western basin
Paleocean circulation
The configuration was different, but not the rate of circulation?
Curry and Oppo (2005)