Clues to Ocean History: a Brief Overview of Proxies
G. Wefer l *, W.H. Berger, J. Bijma l and G. Fischerl
1 Universitat Bremen, Fachbereich Geowissenschaften, Postfach 33 04 40,
D-28334 Bremen, Germany
Contents
2 Scripps Institution of Oceanography, La Jolla, CA. 92093, USA
*corresponding author (e-mail):gwefer@allgeo.uni-bremen.de
page
Abstract .......................................................................................................................................... 1
Introduction .................................................................................................................................... 2
What is a proxy? ............................................................................................................................ 5
Types of proxies ............................................................................................................................. 6
Temperature estimates from microfossil assemblages ................................................................... 6
Temperature estimates from oxygen isotope composition ........................................................... 10
Temperature estimates from Mg/Ca ratios ................................................................................... 14
Temperature estimates from alkenones ........................................................................................ 15
Salinity estimates ......................................................................................................................... 18
Reconstruction of bottom-water age and flow ............................................................................. 19
Reconstruction of productivity from organic matter .................................................................... 23
Reconstruction of productivity from carbonate, opal, and barite ................................................. 25
Reconstruction of productivity from microfossil assemblages .................................................... 28
Reconstruction of nutrient availability in the ocean ..................................................................... 29
Toward reconstruction of surface water PC02 (and atmospheric pC02) ••••••••••••••••••••••••••••••••••••• 35
Reconstruction of wind transport and conditions on adjacent land areas .................................... 38
Conclusions .................................................................................................................................. 39
References .................................................................................................................................... 40
Appendix I. List of important proxies ......................................................................................... 56
Abstract: The reconstruction of ocean history employs a large variety of methods with origins in the
biological, chemical, and physical sciences, and uses modem statistical techniques for the
interpretation of extensive and complex data sets. Various sediment properties deliver useful
information for reconstructing environmental parameters. Those properties that have a close
relationship to environmental parameters are called "proxy variables" ("proxies" for short). Proxies
are measurable descriptors for desired (but unobservable) variables. Surface water temperature is
probably the most important parameter for describing the conditions of past oceans and is crucial for
climate modelling. Proxies for temperature are: abundance of microfossils dwelling in surface waters,
From FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examples from the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 1-68
G. Wefer l *, W.H. Berger, J. Bijma l and G. Fischerl
1 Universitat Bremen, Fachbereich Geowissenschaften, Postfach 33 04 40,
D-28334 Bremen, Germany
Contents
2 Scripps Institution of Oceanography, La Jolla, CA. 92093, USA
*corresponding author (e-mail):gwefer@allgeo.uni-bremen.de
page
Abstract .......................................................................................................................................... 1
Introduction .................................................................................................................................... 2
What is a proxy? ............................................................................................................................ 5
Types of proxies ............................................................................................................................. 6
Temperature estimates from microfossil assemblages ................................................................... 6
Temperature estimates from oxygen isotope composition ........................................................... 10
Temperature estimates from Mg/Ca ratios ................................................................................... 14
Temperature estimates from alkenones ........................................................................................ 15
Salinity estimates ......................................................................................................................... 18
Reconstruction of bottom-water age and flow ............................................................................. 19
Reconstruction of productivity from organic matter .................................................................... 23
Reconstruction of productivity from carbonate, opal, and barite ................................................. 25
Reconstruction of productivity from microfossil assemblages .................................................... 28
Reconstruction of nutrient availability in the ocean ..................................................................... 29
Toward reconstruction of surface water PC02 (and atmospheric pC02) ••••••••••••••••••••••••••••••••••••• 35
Reconstruction of wind transport and conditions on adjacent land areas .................................... 38
Conclusions .................................................................................................................................. 39
References .................................................................................................................................... 40
Appendix I. List of important proxies ......................................................................................... 56
Abstract: The reconstruction of ocean history employs a large variety of methods with origins in the
biological, chemical, and physical sciences, and uses modem statistical techniques for the
interpretation of extensive and complex data sets. Various sediment properties deliver useful
information for reconstructing environmental parameters. Those properties that have a close
relationship to environmental parameters are called "proxy variables" ("proxies" for short). Proxies
are measurable descriptors for desired (but unobservable) variables. Surface water temperature is
probably the most important parameter for describing the conditions of past oceans and is crucial for
climate modelling. Proxies for temperature are: abundance of microfossils dwelling in surface waters,
From FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examples from the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 1-68