Carbonate Dissolution in the Deep-Sea: Methods, Quantification and
Paleoceanographic Application
N. Dittert l ,2*, K.-H. Baumann 2 , T. Bickert 2 , R. Henrich 2 ,
R. Huber, H. KinkeF and H. Meggers2
lInstitut Universitaire Europeen de la Mer, Technopole Brest-Iroise, Place Nicolas Copernic,
F-29280 Plouzane, France
2Universitdt Bremen, Fachbereich Geowissenschaften, Postfach 33 0440,
D-28334 Bremen, Germany
*corresponding author (e-mail):nicolas.dittert@univ-brest.fr
Abstract: Understanding spatial and temporal changes in oceanic carbonate dissolution and
preservation patterns is of key importance for testing models which seek to explain past changes in
atmospheric pC0 2 and surface water PC0 2 through changes in the global carbon cycle. As part of
the South Atlantic Dissolution Experiment, three deep-sea transects covering areas above and
below the calcite lysocline into the Brazil and through the Cape Basin were investigated. Our work
includes (l) determination of sediment surface assemblages of coccolithophores and planktic
foraminifera; (2) SEM ultrastructure analysis of the planktic foraminifera Globigerina bulloides; and
(3) comparative assessment of different carbonate dissolution proxies. We find that all dissolution
proxies are able to distinguish the area above the calcite lysocline from the area below. Moreover,
some parameters are qualified to distinguish the upper continental margin of upwelling areas from
the open ocean. Regarding three different oceanographic regimes, only the carbonate ion content
and the percentage of sediment carbonate content put us in the position to determine the total scale
of the calcite transition zone. If these parameters are not available, a combination ofthe Globigerina
bulloides Dissolution Index, the Calcidiscus leptoporus - Emiliania huxleyi Dissolution Index, and
the rain ratio give the best approach to the authentic conditions.
Prologue
By publishing his article "On the Distribution ofthe
Pelagic Foraminifera at the Surface and on the
Floor of the Ocean" as a monthly review of sci entific progress, Murray (1897) laid the foundations
of a topic that still occupies scientists 100 years
later: He realized that the gradual disappearance
of calcareous shells with increasing water depths
is due to the solvent action of deep-sea water. The
importance of the ocean as one principal global
carbon reservoir and the close relationship between
CO 2 and climatic change led oceanographers and
paleoceanographers to explore intensively the balance between biogenic production and CaC0 3 accumulation-dissolution through time.
Introduction
As early as in the late 19th century Murray and
Renard (1891) realized that the distribution and
character of Globigerina ooze are governed by the
bio-/zoogeography of the living organisms in surface
currents and by the chemistry of deep-sea water
that is responsible for the modification of the sediment and organism assemblages. In particular, they
noted that dissolution works selectively, and that
below a depth of about 4,000 m in the central
Pacific it destroys essentially all calcareous matter.
In addition, Murray (1897) explained the different
shell dissolution patterns observed by the powerful
solvent action of decaying organic matter on carbonates. With expanded knowledge in microFrom FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examplesfrom the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 255-284
Paleoceanographic Application
N. Dittert l ,2*, K.-H. Baumann 2 , T. Bickert 2 , R. Henrich 2 ,
R. Huber, H. KinkeF and H. Meggers2
lInstitut Universitaire Europeen de la Mer, Technopole Brest-Iroise, Place Nicolas Copernic,
F-29280 Plouzane, France
2Universitdt Bremen, Fachbereich Geowissenschaften, Postfach 33 0440,
D-28334 Bremen, Germany
*corresponding author (e-mail):nicolas.dittert@univ-brest.fr
Abstract: Understanding spatial and temporal changes in oceanic carbonate dissolution and
preservation patterns is of key importance for testing models which seek to explain past changes in
atmospheric pC0 2 and surface water PC0 2 through changes in the global carbon cycle. As part of
the South Atlantic Dissolution Experiment, three deep-sea transects covering areas above and
below the calcite lysocline into the Brazil and through the Cape Basin were investigated. Our work
includes (l) determination of sediment surface assemblages of coccolithophores and planktic
foraminifera; (2) SEM ultrastructure analysis of the planktic foraminifera Globigerina bulloides; and
(3) comparative assessment of different carbonate dissolution proxies. We find that all dissolution
proxies are able to distinguish the area above the calcite lysocline from the area below. Moreover,
some parameters are qualified to distinguish the upper continental margin of upwelling areas from
the open ocean. Regarding three different oceanographic regimes, only the carbonate ion content
and the percentage of sediment carbonate content put us in the position to determine the total scale
of the calcite transition zone. If these parameters are not available, a combination ofthe Globigerina
bulloides Dissolution Index, the Calcidiscus leptoporus - Emiliania huxleyi Dissolution Index, and
the rain ratio give the best approach to the authentic conditions.
Prologue
By publishing his article "On the Distribution ofthe
Pelagic Foraminifera at the Surface and on the
Floor of the Ocean" as a monthly review of sci entific progress, Murray (1897) laid the foundations
of a topic that still occupies scientists 100 years
later: He realized that the gradual disappearance
of calcareous shells with increasing water depths
is due to the solvent action of deep-sea water. The
importance of the ocean as one principal global
carbon reservoir and the close relationship between
CO 2 and climatic change led oceanographers and
paleoceanographers to explore intensively the balance between biogenic production and CaC0 3 accumulation-dissolution through time.
Introduction
As early as in the late 19th century Murray and
Renard (1891) realized that the distribution and
character of Globigerina ooze are governed by the
bio-/zoogeography of the living organisms in surface
currents and by the chemistry of deep-sea water
that is responsible for the modification of the sediment and organism assemblages. In particular, they
noted that dissolution works selectively, and that
below a depth of about 4,000 m in the central
Pacific it destroys essentially all calcareous matter.
In addition, Murray (1897) explained the different
shell dissolution patterns observed by the powerful
solvent action of decaying organic matter on carbonates. With expanded knowledge in microFrom FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examplesfrom the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 255-284