and subjecive overview of some of the most important discoveries of the past decades will be presented.
Paleophysiography: When Alfred Wegener hypothesized about the “origin of continents and ocean” between
1912 and 1929 he had to do so without sufficient information about the nature of the ocean floor; despite this deficiency he succeeded to interpret correctly many of the
paleogeographic changes of the distribution of land and
sea through time. In modern times (cf. Müller et al., this
volume) the information deduced from the age distribution of sea-floor spreading magnetic anomalies and of
our understanding of the subsidence of ocean crust after
its formation due to its thermal history (Sclater et al., this
volume) allows us to draw a detailed picture of the
paleophysiography of the location, shape including
depths, size, and volume of the ocean basins and their evolution through time, at least since mid-Mesozoic times
(cf. Müller et al., this volume). Basically it is the evolution
of planet Earth from a geography with one large continental land mass versus one contiguous ocean basin at the end
of the Paleozoic to the modern one with numerous “small”
continents and an ocean basin fragmented into many
subbasins.
Plate tectonics and climate: The major changes of the
physiography of ocean basins, in particular tectonically
driven changes of the seaways between ocean basins, were
clear since Wegener’s (1912–2005) publications.
A modern example is described in Haug and Tiedemann
(1998), who reasoned that the closure of the Isthmus of
Panama led to environmental changes resulting in the
deteriorating livelihood of the late Holocene Central
American populations. However, more recently, a much
closer (and hitherto) poorly understood correlation
between volcanic/tectonic processes at the mid-ocean
ridges and the evolution of climate seems to emerge. Van
der Meer et al., 2014 have determined plate tectonic controls on atmospheric carbon dioxide levels in the atmosphere since the Triassic and speculate about an intricate
interrelationship between subduction rates and carbon
dioxide levels in the atmosphere, controlled by processes
over time scales of 10 to 100 million years. However,
recent comparisons of volcanic activity on Iceland and
the observations of the similarity of the fine grain of the
morphology of volcanic structures of the mid-ocean ridge
regions with Late Cenozoic climate variability seem to
suggest that plate tectonic and climate variability are much
more closely linked and over much shorter time scales
than presumed hitherto.
Plate stratigraphy: The mode of the general subsidence
of the ocean floor and the mechanisms of pelagic sediment
formation generate a characteristic stratigraphic pattern of
sediments on top of the ocean crust, as demonstrated in
many cores of the various deep-sea drilling projects
(cf. Suyehiro, this volume, and discussed by Kennett,
1982 and Van Andel et al., 1975). The global patterns of
pelagic sediment formation (cf. Lyle, this volume) and in
particular the water depth-dependent aragonite and calcite
differential dissolution as well as the existence of the
calcite lysocline and Calcite Compensation Depth (CCD,
cf. Berger, this volume) result in the preservation of the
ubiquitous calcareous deep-sea deposits only in welldefined regions and depth intervals (Van Andel et al.,
1977; Ehrmann and Thiede, 1985). Young ocean crust lies
usually above the CCD giving place to the formation of
calcareous oozes if not biogenic siliceous oozes are
formed under highly productive ocean surface waters. In
high latitudes the input of terrigeneous fines dominates
ocean sediment formation. Old ocean crust which had
sunk below the CCD in temperate to tropical regions is
mostly covered by red deep-sea clays.
Marine microfossils and their environmental record:
Marine microfossils have been producing the first proxies
for paleoceanographic and paleoclimatic records deduced
from ocean sediment cores. This was first realized by
Schott (1935, in Correns and Schott, 1935/37), who
mapped out planktonic foraminiferal distributions in sediment cores from the South Atlantic and who was able to
argue that these cores covered the transition from the last
glacial to the much warmer Holocene. In the meantime it
has been recognized that all planktonic microfossils reveal
distribution patterns according to temperature zonations in
the ocean and that they are superb indicators which can be
exploited by using modern analog techniques (Hale and
Pflaumann, 1999), a technique which has been developed
by Imbrie and Kipp (1971) during the early stages of the
CLIMAP project (Cline and Hays, 1976). In the meantime
this method has been applied to many other examples,
cf. Pflaumann et al. (2003).
Paleotemperature, paleosalinity, ice in the ocean: When
reconstructing the hydrography of former oceans, one
needs to quantify its basic hydrographic properties. This is
relatively easy but sometimes ambiguous (Stärz et al.,
2012) for ice in the oceans, because it leaves traces in the
distribution of ice-rafted sediment components and of biotic
remains of organisms (diatoms) adapted to the life in and
under the sea ice (Thiede et al., 2011; Stickley et al.,
2009). The relatively recent drilling on Lomosow Ridge
close to the North Pole (Moran et al., 2006) suggests that
the central Arctic Ocean at least was seasonally sea-ice covered in the middle Eocene, milions of years before the
assumed initial glaciation of the northern hemisphere.
Paleotemperatures and –salinities can be quantitatively
established by a wide variety of biotic and geochemical
methods as summarized by Fischer and Wefer, 1999.
Fractionation of Oxygen isotopes in relation to global
ice volume: When Emiliani studied the O-Isotpe ratios in
forminiferal shells from Upper Quaternary deep sea sediments (Emiliani, 1955), he considered the O-isotopic variations to be mainly due to temperature changes between
Glacials and Interglacials. However, even though benthic
foraminifers showed similar variations with a clear offset,
it would not have been possible to invoke the same temperature variations as their cause. And it was Shackleton
(1987) who linked the O-isotope fractionation observed
in the foraminiferal records to the late Quaternary climate
variability (ice volume, sea-level) assuming that the major
PALEOCEANOGRAPHY
629
Paleophysiography: When Alfred Wegener hypothesized about the “origin of continents and ocean” between
1912 and 1929 he had to do so without sufficient information about the nature of the ocean floor; despite this deficiency he succeeded to interpret correctly many of the
paleogeographic changes of the distribution of land and
sea through time. In modern times (cf. Müller et al., this
volume) the information deduced from the age distribution of sea-floor spreading magnetic anomalies and of
our understanding of the subsidence of ocean crust after
its formation due to its thermal history (Sclater et al., this
volume) allows us to draw a detailed picture of the
paleophysiography of the location, shape including
depths, size, and volume of the ocean basins and their evolution through time, at least since mid-Mesozoic times
(cf. Müller et al., this volume). Basically it is the evolution
of planet Earth from a geography with one large continental land mass versus one contiguous ocean basin at the end
of the Paleozoic to the modern one with numerous “small”
continents and an ocean basin fragmented into many
subbasins.
Plate tectonics and climate: The major changes of the
physiography of ocean basins, in particular tectonically
driven changes of the seaways between ocean basins, were
clear since Wegener’s (1912–2005) publications.
A modern example is described in Haug and Tiedemann
(1998), who reasoned that the closure of the Isthmus of
Panama led to environmental changes resulting in the
deteriorating livelihood of the late Holocene Central
American populations. However, more recently, a much
closer (and hitherto) poorly understood correlation
between volcanic/tectonic processes at the mid-ocean
ridges and the evolution of climate seems to emerge. Van
der Meer et al., 2014 have determined plate tectonic controls on atmospheric carbon dioxide levels in the atmosphere since the Triassic and speculate about an intricate
interrelationship between subduction rates and carbon
dioxide levels in the atmosphere, controlled by processes
over time scales of 10 to 100 million years. However,
recent comparisons of volcanic activity on Iceland and
the observations of the similarity of the fine grain of the
morphology of volcanic structures of the mid-ocean ridge
regions with Late Cenozoic climate variability seem to
suggest that plate tectonic and climate variability are much
more closely linked and over much shorter time scales
than presumed hitherto.
Plate stratigraphy: The mode of the general subsidence
of the ocean floor and the mechanisms of pelagic sediment
formation generate a characteristic stratigraphic pattern of
sediments on top of the ocean crust, as demonstrated in
many cores of the various deep-sea drilling projects
(cf. Suyehiro, this volume, and discussed by Kennett,
1982 and Van Andel et al., 1975). The global patterns of
pelagic sediment formation (cf. Lyle, this volume) and in
particular the water depth-dependent aragonite and calcite
differential dissolution as well as the existence of the
calcite lysocline and Calcite Compensation Depth (CCD,
cf. Berger, this volume) result in the preservation of the
ubiquitous calcareous deep-sea deposits only in welldefined regions and depth intervals (Van Andel et al.,
1977; Ehrmann and Thiede, 1985). Young ocean crust lies
usually above the CCD giving place to the formation of
calcareous oozes if not biogenic siliceous oozes are
formed under highly productive ocean surface waters. In
high latitudes the input of terrigeneous fines dominates
ocean sediment formation. Old ocean crust which had
sunk below the CCD in temperate to tropical regions is
mostly covered by red deep-sea clays.
Marine microfossils and their environmental record:
Marine microfossils have been producing the first proxies
for paleoceanographic and paleoclimatic records deduced
from ocean sediment cores. This was first realized by
Schott (1935, in Correns and Schott, 1935/37), who
mapped out planktonic foraminiferal distributions in sediment cores from the South Atlantic and who was able to
argue that these cores covered the transition from the last
glacial to the much warmer Holocene. In the meantime it
has been recognized that all planktonic microfossils reveal
distribution patterns according to temperature zonations in
the ocean and that they are superb indicators which can be
exploited by using modern analog techniques (Hale and
Pflaumann, 1999), a technique which has been developed
by Imbrie and Kipp (1971) during the early stages of the
CLIMAP project (Cline and Hays, 1976). In the meantime
this method has been applied to many other examples,
cf. Pflaumann et al. (2003).
Paleotemperature, paleosalinity, ice in the ocean: When
reconstructing the hydrography of former oceans, one
needs to quantify its basic hydrographic properties. This is
relatively easy but sometimes ambiguous (Stärz et al.,
2012) for ice in the oceans, because it leaves traces in the
distribution of ice-rafted sediment components and of biotic
remains of organisms (diatoms) adapted to the life in and
under the sea ice (Thiede et al., 2011; Stickley et al.,
2009). The relatively recent drilling on Lomosow Ridge
close to the North Pole (Moran et al., 2006) suggests that
the central Arctic Ocean at least was seasonally sea-ice covered in the middle Eocene, milions of years before the
assumed initial glaciation of the northern hemisphere.
Paleotemperatures and –salinities can be quantitatively
established by a wide variety of biotic and geochemical
methods as summarized by Fischer and Wefer, 1999.
Fractionation of Oxygen isotopes in relation to global
ice volume: When Emiliani studied the O-Isotpe ratios in
forminiferal shells from Upper Quaternary deep sea sediments (Emiliani, 1955), he considered the O-isotopic variations to be mainly due to temperature changes between
Glacials and Interglacials. However, even though benthic
foraminifers showed similar variations with a clear offset,
it would not have been possible to invoke the same temperature variations as their cause. And it was Shackleton
(1987) who linked the O-isotope fractionation observed
in the foraminiferal records to the late Quaternary climate
variability (ice volume, sea-level) assuming that the major
PALEOCEANOGRAPHY
629