88
Hale and Pflaumann
small cluster north of the Cape Verde Islands off
northern Africa, and in GeoB 2204 of a group off
the coast of southern Brazil at about 25° to 30 0 S,
but not within the influence of any present-day highproductivity systems.
Although the SIMMAX MATis considered to
be a valid technique for estimating past surface
temperatures, we can not determine with statistical certainty the accuracy of the method. Elements
of statistical error associated with the microsplitting
techniques during sample preparation as well as the
subjectivity of taxonomic questions certainly result
in some inconsistency and error. The effects of
dissolution are also difficult to assess. For these
reasons it is important that temperature estimates
be carried out on a number of cores using different methods, particularly with a combination of the
SIMMAX MAT and the U;7 index. A study of this
sort was carried out on a core in the northeast
Pacific by Prahl et al. (1995) using a radiolarian
transfer function in conjunction with the U;7 index method. Because these two techniques are
based on different assumptions, such studies may
reveal the weaknesses in both methods and result
in refinement of our ability to estimate
paleotemperature. Of course, appropriate cores
with sufficient planktonic foraminifera for the MAT
and sufficient organic material for the U;7 method
must be found. Although modern technology has
provided us with increasingly accurate instruments
for making physical measurements of the oceans,
we will never be able to reach back into the past
with these to determine the parameters with comparable certainty. We are forced to employ innovative alternative proxies, all of which are based
on a number of assumptions, and we can only reach
optimum levels of confidence by using all of the
reasonable tools available.
Acknowledgments
Thanks to the scientists and crew of the R.V.
METEOR for their dedication in obtaining cores
and samples during the three cruises. We would
also like to thank M. Segl and B. Meyer-Schack
for their assistance in carrying out the isotopic
analyses. We are grateful to R. Schneider, T.
Bickert, and S. Mulitza for providing insight and
helpful suggestions in numerous early discussions.
The manuscript was significantly improved through
the critical reviews ofS. Snyder and T. Crowley.
The research was funded by the Deutsche
F orschungsgemeinschaft (Sonderforschungsbereich 261 at Bremen University, Contribution No.
187). Data are available under www.pangaea.de/
Projects/SFB261.
References
Be A WH (1967) Fiches d'Identification du zooplancton.
Conseil Pennanent International pour I 'Exploration
de la Mer. Zooplankton sheet 108. Charlottenlund
Slot, Danemark
Be A WH, Tolderlund DS (1971) Distribution and ecology ofliving planktonic foraminifera in surface waters of the Atlantic and Indian Oceans. In: Funnell
BM, Riedel RR (eds) The Micropaleontology of
the Oceans. Cambridge Univ Press, New York,
pp 105-149
Bleil UV, SpieB V, Wefer G (1994) Geo Bremen SOUTH
A TLANTIC(1993), Cruise No. 23, 4 Feb. - 12 April
1993. MElEOR Ber Univ Hamburg 94-1, pp 1-261
Brassell SC, Eglinton G, Marlowe IT, Pflaumann U,
Samthein M (1986) Molecular stratigraphy: A new
tool for climatic assessment. Nature 320: 129-133
Broecker W (1995) Cooling the tropics. Nature 376:
212-213
Broecker W (1996) Glacial climate in the tropics. Science
272: 1902-1904
CLlMAP Project Members (1981) Seasonal reconstructions of the Earth's surface at the last glacial maximum. Geol Soc Amer Map and Chart Series MC-36
Davis JC (1986) Cluster analysis. In: Statistics and Data
Analysis in Geology. J Wiley & Sons, New York,
pp502-515
Emiliani C (1955) Pleistocene temperatures. J Geo163:
538-578
Epstein S, Buchsbaum R, Lowenstam HA, Urey HC
(1953) Revised carbonate water isotopic temperature
scale. GSA Bulletin 64: 1315-1326
Fairbanks RG, Sverdlove M, Free R, Wiebe PH, Be A WH
(1982) Vertical distribution and isotopic fractionation
ofliving planktonic foraminifera from the Panama
Basin. Nature 298: 841-844
Fishbein E, PattersonRT (1993) Error-weigbtedmaximum
likelihood (EWML): a new statistically based method
to cluster quantitative micropaleontological data. J
PaleontoI67(3): 475-486
Hale and Pflaumann
small cluster north of the Cape Verde Islands off
northern Africa, and in GeoB 2204 of a group off
the coast of southern Brazil at about 25° to 30 0 S,
but not within the influence of any present-day highproductivity systems.
Although the SIMMAX MATis considered to
be a valid technique for estimating past surface
temperatures, we can not determine with statistical certainty the accuracy of the method. Elements
of statistical error associated with the microsplitting
techniques during sample preparation as well as the
subjectivity of taxonomic questions certainly result
in some inconsistency and error. The effects of
dissolution are also difficult to assess. For these
reasons it is important that temperature estimates
be carried out on a number of cores using different methods, particularly with a combination of the
SIMMAX MAT and the U;7 index. A study of this
sort was carried out on a core in the northeast
Pacific by Prahl et al. (1995) using a radiolarian
transfer function in conjunction with the U;7 index method. Because these two techniques are
based on different assumptions, such studies may
reveal the weaknesses in both methods and result
in refinement of our ability to estimate
paleotemperature. Of course, appropriate cores
with sufficient planktonic foraminifera for the MAT
and sufficient organic material for the U;7 method
must be found. Although modern technology has
provided us with increasingly accurate instruments
for making physical measurements of the oceans,
we will never be able to reach back into the past
with these to determine the parameters with comparable certainty. We are forced to employ innovative alternative proxies, all of which are based
on a number of assumptions, and we can only reach
optimum levels of confidence by using all of the
reasonable tools available.
Acknowledgments
Thanks to the scientists and crew of the R.V.
METEOR for their dedication in obtaining cores
and samples during the three cruises. We would
also like to thank M. Segl and B. Meyer-Schack
for their assistance in carrying out the isotopic
analyses. We are grateful to R. Schneider, T.
Bickert, and S. Mulitza for providing insight and
helpful suggestions in numerous early discussions.
The manuscript was significantly improved through
the critical reviews ofS. Snyder and T. Crowley.
The research was funded by the Deutsche
F orschungsgemeinschaft (Sonderforschungsbereich 261 at Bremen University, Contribution No.
187). Data are available under www.pangaea.de/
Projects/SFB261.
References
Be A WH (1967) Fiches d'Identification du zooplancton.
Conseil Pennanent International pour I 'Exploration
de la Mer. Zooplankton sheet 108. Charlottenlund
Slot, Danemark
Be A WH, Tolderlund DS (1971) Distribution and ecology ofliving planktonic foraminifera in surface waters of the Atlantic and Indian Oceans. In: Funnell
BM, Riedel RR (eds) The Micropaleontology of
the Oceans. Cambridge Univ Press, New York,
pp 105-149
Bleil UV, SpieB V, Wefer G (1994) Geo Bremen SOUTH
A TLANTIC(1993), Cruise No. 23, 4 Feb. - 12 April
1993. MElEOR Ber Univ Hamburg 94-1, pp 1-261
Brassell SC, Eglinton G, Marlowe IT, Pflaumann U,
Samthein M (1986) Molecular stratigraphy: A new
tool for climatic assessment. Nature 320: 129-133
Broecker W (1995) Cooling the tropics. Nature 376:
212-213
Broecker W (1996) Glacial climate in the tropics. Science
272: 1902-1904
CLlMAP Project Members (1981) Seasonal reconstructions of the Earth's surface at the last glacial maximum. Geol Soc Amer Map and Chart Series MC-36
Davis JC (1986) Cluster analysis. In: Statistics and Data
Analysis in Geology. J Wiley & Sons, New York,
pp502-515
Emiliani C (1955) Pleistocene temperatures. J Geo163:
538-578
Epstein S, Buchsbaum R, Lowenstam HA, Urey HC
(1953) Revised carbonate water isotopic temperature
scale. GSA Bulletin 64: 1315-1326
Fairbanks RG, Sverdlove M, Free R, Wiebe PH, Be A WH
(1982) Vertical distribution and isotopic fractionation
ofliving planktonic foraminifera from the Panama
Basin. Nature 298: 841-844
Fishbein E, PattersonRT (1993) Error-weigbtedmaximum
likelihood (EWML): a new statistically based method
to cluster quantitative micropaleontological data. J
PaleontoI67(3): 475-486