by the chief scientists. The materials recovered by drilling
resulted in a major jump in biostratigraphic resolution –
soon it became possible to date samples within sequences
with a temporal resolution of less than a million years relative to some standard. The first major result was full confirmation of the theory of seafloor spreading: Sediments
overlying the “basement” basalt showed the exact age
predicted by the geophysicists from counting magnetic
anomalies. Occasionally, sediments were somewhat younger, which means that the basaltic rock was bare for a
while, before it collected sediments. Other major results
were more subtle but have had far-reaching implications
for our understanding of the coevolution of life and climate and for the role of the ocean in climatic change over
long periods of time.
In the early years of deep-sea drilling, present sedimentation patterns were assumed to be static, so that downcore changes would be interpreted mainly in terms of
motions of the seafloor. It soon became clear, however,
that the ocean’s productivity changed markedly through
geologic time, which produced large changes in sedimentation patterns. Also, it became evident that changes in
ocean conditions (as reflected in sediments) were quite
sudden at certain times and that such “steps” in climatic
change were associated with reorganizations of the marine
biosphere, including extinctions and subsequent radiations. The most intriguing period in the ocean’s history,
in this regard, proved to be the transition between the Cretaceous and the Tertiary, which witnessed large-scale
extinction of tropical planktonic organisms (as well as
many other terrestrial and oceanic organisms).
The importance of the deep-sea record for the reconstruction of Earth’s history for the last 100 million years
or so became obvious very quickly. The record on land
is patchy and incomplete by nature – land is eroded and
delivers sediment to the sea. This renders suspect all arguments about the pace of evolution that depend on a continuous record (Darwin pointed this out a long time ago).
Only the record in the deep ocean can promise complete
sequences, and even here gaps prove to be quite common
in many settings. The gaps are not distributed randomly
but occur preferentially just where conditions change.
This illustrates a certain obstinacy of the ocean in yielding
up the secrets of its history, something that many marine
geologists have come to appreciate.
Deep-sea drilling has gone through important steps of
evolution. While the technique to reenter a drill hole
through a cone several times to exchanging the actual drilling tool has already been developed during DSDP and
ODP times, the engaged international scientific community is nor striving for further progress. For the years
2003–2023, it has been decided to continue these efforts
under the frame of IODP (Integrated Ocean Discovery
Program, cf. Kiyoshi, this volume). Instead of using only
one drilling platform with a limited scope of the scientific
problems to be attacked, IODP is now trying to drill
deeper and more dangerous areas than before by
employing the Japanese Chikyu which can deploy a
riser-protected drill string thus allowing into the seismically active zones of Japan, for example. JOIDES Resolution is still available to conduct drilling in all major ocean
basins, with the cold subpolar deep-sea basins being much
in the focus.
A system of Mission Specific Platforms has been
equipped to drill in shallow shelf seas for determining,
for example, timing and extent of global sea-level
changes, the history of the Great Barrier Reef, or the central Arctic Ocean, putting the age of the first Northern
Hemisphere ice covers back into the Eocene. In addition
to drilling, technologies have been developed to install
numerous measuring devices or observatories on a permanent or semipermanent basis in some of the drill holes.
One of the most notable aspects of deep ocean drilling –
now improved through the deployment of the larger
drilling vessels JOIDES Resolution and Chikyu – is the
creation of an international community of marine geologists, hundreds of scientists from around the world who
were shipmates at one time or another, eagerly listening
for the driller’s call “core-on-deck” and sharing the thrill
of exploring where nobody had gone before.
The treasures of the seafloor
After the discovery of the principles in plate tectonics and
mapping of the oceanic spreading centers, it was only a
question of time to dive down to the production centers
of new seafloor. Here, along the spreading axes, hot mantle material is upwelling and rises as magma and emerges
as lava produced by cooling new oceanic crust. In 1977
scientists from the Scripps Institution of Oceanography
used the deep submersible Alvin to dive to the East Pacific
Rise. These scientists described the first time visually
active hydrothermal venting and related processes. To
their surprise they found a diverse inventory of venting
phenomena such as hot water chimneys separated into
black and white smokers along with chemosynthetic life
forms which were completely unknown before
(Londsdale, 1977). For the history of hydrothermal vent
discovery, see “Hydrothermalism” (this encyclopedia).
The discovery of chemosynthetic life initiated the development of new biological theory, such as the assumption
of Gold (1992) who postulated a phylogenetic pathway
of organisms from the “Deep Hot Biosphere” to the
surface.
Predicted by economic geologists who had studied
hydrothermal sulfides on land, in the course of exploring
marine hydrothermal vents, significant polymetallic
enrichment was found in the vicinity of the vents which
was assigned to hydrothermal activities at or in the vicinity
of the spreading centers. The identification of massive sulfide deposits leads to an intense international activity in
exploration of marine ore reserves (Francheteau et al.,
1979). Saline brines and metalliferous marine muds had
been identified in the Red Sea already in the 1960s of
the last century (Degens and Ross 1969), but the development of a general genetic concept of marine ores could not
MARINE GEOSCIENCES: A SHORT, ECCLECTIC AND WEIGHTED HISTORIC ACCOUNT
443
resulted in a major jump in biostratigraphic resolution –
soon it became possible to date samples within sequences
with a temporal resolution of less than a million years relative to some standard. The first major result was full confirmation of the theory of seafloor spreading: Sediments
overlying the “basement” basalt showed the exact age
predicted by the geophysicists from counting magnetic
anomalies. Occasionally, sediments were somewhat younger, which means that the basaltic rock was bare for a
while, before it collected sediments. Other major results
were more subtle but have had far-reaching implications
for our understanding of the coevolution of life and climate and for the role of the ocean in climatic change over
long periods of time.
In the early years of deep-sea drilling, present sedimentation patterns were assumed to be static, so that downcore changes would be interpreted mainly in terms of
motions of the seafloor. It soon became clear, however,
that the ocean’s productivity changed markedly through
geologic time, which produced large changes in sedimentation patterns. Also, it became evident that changes in
ocean conditions (as reflected in sediments) were quite
sudden at certain times and that such “steps” in climatic
change were associated with reorganizations of the marine
biosphere, including extinctions and subsequent radiations. The most intriguing period in the ocean’s history,
in this regard, proved to be the transition between the Cretaceous and the Tertiary, which witnessed large-scale
extinction of tropical planktonic organisms (as well as
many other terrestrial and oceanic organisms).
The importance of the deep-sea record for the reconstruction of Earth’s history for the last 100 million years
or so became obvious very quickly. The record on land
is patchy and incomplete by nature – land is eroded and
delivers sediment to the sea. This renders suspect all arguments about the pace of evolution that depend on a continuous record (Darwin pointed this out a long time ago).
Only the record in the deep ocean can promise complete
sequences, and even here gaps prove to be quite common
in many settings. The gaps are not distributed randomly
but occur preferentially just where conditions change.
This illustrates a certain obstinacy of the ocean in yielding
up the secrets of its history, something that many marine
geologists have come to appreciate.
Deep-sea drilling has gone through important steps of
evolution. While the technique to reenter a drill hole
through a cone several times to exchanging the actual drilling tool has already been developed during DSDP and
ODP times, the engaged international scientific community is nor striving for further progress. For the years
2003–2023, it has been decided to continue these efforts
under the frame of IODP (Integrated Ocean Discovery
Program, cf. Kiyoshi, this volume). Instead of using only
one drilling platform with a limited scope of the scientific
problems to be attacked, IODP is now trying to drill
deeper and more dangerous areas than before by
employing the Japanese Chikyu which can deploy a
riser-protected drill string thus allowing into the seismically active zones of Japan, for example. JOIDES Resolution is still available to conduct drilling in all major ocean
basins, with the cold subpolar deep-sea basins being much
in the focus.
A system of Mission Specific Platforms has been
equipped to drill in shallow shelf seas for determining,
for example, timing and extent of global sea-level
changes, the history of the Great Barrier Reef, or the central Arctic Ocean, putting the age of the first Northern
Hemisphere ice covers back into the Eocene. In addition
to drilling, technologies have been developed to install
numerous measuring devices or observatories on a permanent or semipermanent basis in some of the drill holes.
One of the most notable aspects of deep ocean drilling –
now improved through the deployment of the larger
drilling vessels JOIDES Resolution and Chikyu – is the
creation of an international community of marine geologists, hundreds of scientists from around the world who
were shipmates at one time or another, eagerly listening
for the driller’s call “core-on-deck” and sharing the thrill
of exploring where nobody had gone before.
The treasures of the seafloor
After the discovery of the principles in plate tectonics and
mapping of the oceanic spreading centers, it was only a
question of time to dive down to the production centers
of new seafloor. Here, along the spreading axes, hot mantle material is upwelling and rises as magma and emerges
as lava produced by cooling new oceanic crust. In 1977
scientists from the Scripps Institution of Oceanography
used the deep submersible Alvin to dive to the East Pacific
Rise. These scientists described the first time visually
active hydrothermal venting and related processes. To
their surprise they found a diverse inventory of venting
phenomena such as hot water chimneys separated into
black and white smokers along with chemosynthetic life
forms which were completely unknown before
(Londsdale, 1977). For the history of hydrothermal vent
discovery, see “Hydrothermalism” (this encyclopedia).
The discovery of chemosynthetic life initiated the development of new biological theory, such as the assumption
of Gold (1992) who postulated a phylogenetic pathway
of organisms from the “Deep Hot Biosphere” to the
surface.
Predicted by economic geologists who had studied
hydrothermal sulfides on land, in the course of exploring
marine hydrothermal vents, significant polymetallic
enrichment was found in the vicinity of the vents which
was assigned to hydrothermal activities at or in the vicinity
of the spreading centers. The identification of massive sulfide deposits leads to an intense international activity in
exploration of marine ore reserves (Francheteau et al.,
1979). Saline brines and metalliferous marine muds had
been identified in the Red Sea already in the 1960s of
the last century (Degens and Ross 1969), but the development of a general genetic concept of marine ores could not
MARINE GEOSCIENCES: A SHORT, ECCLECTIC AND WEIGHTED HISTORIC ACCOUNT
443