be accomplished before the discoveries of the hydrothermal marine sulfides (Hannington et al., 2011). Together
with the discovery of hydrothermal sulfides along spreading centers of the oceans, polymetallic (manganese) nodules covering wide areas of the oceanic basins have
raised international interest during the last decades of the
twentieth century (“Marine Mineral Resources,” “Manganese Nodules,” this encyclopedia). In a kind of “gold
rush,” the developed nations spared neither cost nor effort
to explore marine ore deposits. National and international
consortia (as Interoceanmetal) explored the ocean floor,
whereby areas of the Pacific Ocean between Clarion and
Clipperton Fracture Zones (CCZ) were – and are still –
in the center of interest because of their economic favorability. Despite intense mapping and exploration, an
industrial exploitation of polymetallic nodules has never
started because of the drop in ore prices and unsolved
environmental problems expected to be provoked by an
industrial submarine ore mining. In contrast, commercial
interests currently are focusing on seafloor massive sulfides (SMS) located on convergent plate boundaries
(Rona, 2003), and in 2005 the first commercial SMS survey was launched at the Manus Basin, Papua New Guinea.
During the last third of the twentieth century, the international interest in seabed-bounded mineral resources
exploded in the fear of a depletion of onshore deposits.
So, extensive exploration programs were launched worldwide for sand and gravel, placer (heavy minerals, diamonds, gold), phosphorites, and carbonates on the
continental margins, and most of the adjoining coastal
states exploit mineral offshore resources (“Marine Mineral
Resources,” this encyclopedia) according to international
and national laws. A historical pace forward in this respect
was the establishment of an international legal regime for
the world’s oceans and seas by the United Nations Convention on the Law of the Sea in 1982 (United Nations,
1997). Within the frame of this law, the International Seabed Authority (ISA) based at Kingston, Jamaica, was
founded, a UN body taking care of the organization, regulation, and control of all mineral-related activities in the
international seabed area at the high sea, beyond the limits
of national jurisdiction (for the program see United
Nations, 2004). In addition to mineral deposits, another
resource of the seafloor did raise enormous interest during
the second half of the last century: hydrocarbons (oil and
gas) and gas hydrates (“Energy Resources,” this encyclopedia). After the first discoveries of offshore oil deposits
at the US West Coast, during World War II, their systematic exploration and exploitation started in the Gulf of
Mexico. After the war, worldwide discoveries followed
in the Persian Gulf, Caspian Sea, Arabian Sea and the
North Sea, and many other areas. The last and probably
very big fossil hydrocarbon province is expected to be
found under the Arctic shelf seas and continental margins.
Very soon the areas of interest moved from the shelf to
deepwater fields at water depths >1,500 m so that at the
beginning of the twenty-first century already >50 % of
new discoveries are located at deepwater environments.
Target areas for present future exploration and drilling
activities are the so-called golden triangle of Brazil, the
Gulf of Mexico, and West Africa and the oil and gas in
deepwater environments at continental margins of the
Arctic Ocean. Drilling in the deep ocean raises the risk
of technical accidents and environmental disasters. The
Deepwater Horizon oil spill in the Gulf of Mexico (“Oil
Spill,” this encyclopedia) in 2012 has shown the limits
and threats of current exploitation of marine resources.
Another phenomenon of the world ocean related to
energy sources has been discovered during the 1970s of
the twentieth century: gas hydrates (“Marine Gas
Hydrates,” this encyclopedia). In 1970 the first time
marine gas hydrates have been sampled at the Blake Ridge
(Atlantic continental margin of North America). After
these first discoveries (Kvenvolden and McMenamin
1980), drilling campaigns and international research programs have helped during the last decades to understand
the theoretical background for genesis, structure, and
appearance of marine (and continental) methane hydrates
(cf. Suess et al., 1999). But, we are still far from the exploitation of gas hydrate reserves as energy source.
Oil and gas deposits and accumulation of gas hydrates
are bounded to ocean margins with their sedimentary
wedges hosting continental erosional products with relative high proportions of organic matter descending from
the high productivity of the ocean margin waters. This
organic matter forms the source for hydrocarbons or methane trapped in hydrate cages. For the exploration and
balancing of reserves, a stratigraphic framework for the
sedimentary successions is of extreme importance.
Deep biosphere
The discoveries of the “Deep Hot Biosphere” along with
the investigation of hydrothermalism had raised special
interest in the new “exotic” ecosystems. The ODP and
later on the IODP drilling campaigns lead to a systematic
search for evidences of microbial life in marine sediments
and igneous rocks. These systematic discoveries did
change completely the understanding of the limits of living organisms on our planet (Parkes et al., 2000; D’Hondt
et al., 2004; Jørgensen et al., 2006). For an overview about
discoveries and review articles, see “Deep Biosphere”
(this encyclopedia). Despite the major progress in
research, there are still important questions waiting to be
answered. Among these, the balance of the microbial life,
the energy source of microbial growth, the role of deep
biosphere in the generation and destruction of hydrocarbons and gas hydrates, or in the remobilization of material
from descending lithospheric plates is just a selection of
important question. Origin and evolutionary history of
the deep biosphere and the influence of the marine environments on their abundance is to be addressed for understanding the evolution of ancient life on Earth and will
provide analogs for comparative cosmological studies.
The crucial scientific problems and pathways to solution
have been described as key topics in the science plans of
444
MARINE GEOSCIENCES: A SHORT, ECCLECTIC AND WEIGHTED HISTORIC ACCOUNT
with the discovery of hydrothermal sulfides along spreading centers of the oceans, polymetallic (manganese) nodules covering wide areas of the oceanic basins have
raised international interest during the last decades of the
twentieth century (“Marine Mineral Resources,” “Manganese Nodules,” this encyclopedia). In a kind of “gold
rush,” the developed nations spared neither cost nor effort
to explore marine ore deposits. National and international
consortia (as Interoceanmetal) explored the ocean floor,
whereby areas of the Pacific Ocean between Clarion and
Clipperton Fracture Zones (CCZ) were – and are still –
in the center of interest because of their economic favorability. Despite intense mapping and exploration, an
industrial exploitation of polymetallic nodules has never
started because of the drop in ore prices and unsolved
environmental problems expected to be provoked by an
industrial submarine ore mining. In contrast, commercial
interests currently are focusing on seafloor massive sulfides (SMS) located on convergent plate boundaries
(Rona, 2003), and in 2005 the first commercial SMS survey was launched at the Manus Basin, Papua New Guinea.
During the last third of the twentieth century, the international interest in seabed-bounded mineral resources
exploded in the fear of a depletion of onshore deposits.
So, extensive exploration programs were launched worldwide for sand and gravel, placer (heavy minerals, diamonds, gold), phosphorites, and carbonates on the
continental margins, and most of the adjoining coastal
states exploit mineral offshore resources (“Marine Mineral
Resources,” this encyclopedia) according to international
and national laws. A historical pace forward in this respect
was the establishment of an international legal regime for
the world’s oceans and seas by the United Nations Convention on the Law of the Sea in 1982 (United Nations,
1997). Within the frame of this law, the International Seabed Authority (ISA) based at Kingston, Jamaica, was
founded, a UN body taking care of the organization, regulation, and control of all mineral-related activities in the
international seabed area at the high sea, beyond the limits
of national jurisdiction (for the program see United
Nations, 2004). In addition to mineral deposits, another
resource of the seafloor did raise enormous interest during
the second half of the last century: hydrocarbons (oil and
gas) and gas hydrates (“Energy Resources,” this encyclopedia). After the first discoveries of offshore oil deposits
at the US West Coast, during World War II, their systematic exploration and exploitation started in the Gulf of
Mexico. After the war, worldwide discoveries followed
in the Persian Gulf, Caspian Sea, Arabian Sea and the
North Sea, and many other areas. The last and probably
very big fossil hydrocarbon province is expected to be
found under the Arctic shelf seas and continental margins.
Very soon the areas of interest moved from the shelf to
deepwater fields at water depths >1,500 m so that at the
beginning of the twenty-first century already >50 % of
new discoveries are located at deepwater environments.
Target areas for present future exploration and drilling
activities are the so-called golden triangle of Brazil, the
Gulf of Mexico, and West Africa and the oil and gas in
deepwater environments at continental margins of the
Arctic Ocean. Drilling in the deep ocean raises the risk
of technical accidents and environmental disasters. The
Deepwater Horizon oil spill in the Gulf of Mexico (“Oil
Spill,” this encyclopedia) in 2012 has shown the limits
and threats of current exploitation of marine resources.
Another phenomenon of the world ocean related to
energy sources has been discovered during the 1970s of
the twentieth century: gas hydrates (“Marine Gas
Hydrates,” this encyclopedia). In 1970 the first time
marine gas hydrates have been sampled at the Blake Ridge
(Atlantic continental margin of North America). After
these first discoveries (Kvenvolden and McMenamin
1980), drilling campaigns and international research programs have helped during the last decades to understand
the theoretical background for genesis, structure, and
appearance of marine (and continental) methane hydrates
(cf. Suess et al., 1999). But, we are still far from the exploitation of gas hydrate reserves as energy source.
Oil and gas deposits and accumulation of gas hydrates
are bounded to ocean margins with their sedimentary
wedges hosting continental erosional products with relative high proportions of organic matter descending from
the high productivity of the ocean margin waters. This
organic matter forms the source for hydrocarbons or methane trapped in hydrate cages. For the exploration and
balancing of reserves, a stratigraphic framework for the
sedimentary successions is of extreme importance.
Deep biosphere
The discoveries of the “Deep Hot Biosphere” along with
the investigation of hydrothermalism had raised special
interest in the new “exotic” ecosystems. The ODP and
later on the IODP drilling campaigns lead to a systematic
search for evidences of microbial life in marine sediments
and igneous rocks. These systematic discoveries did
change completely the understanding of the limits of living organisms on our planet (Parkes et al., 2000; D’Hondt
et al., 2004; Jørgensen et al., 2006). For an overview about
discoveries and review articles, see “Deep Biosphere”
(this encyclopedia). Despite the major progress in
research, there are still important questions waiting to be
answered. Among these, the balance of the microbial life,
the energy source of microbial growth, the role of deep
biosphere in the generation and destruction of hydrocarbons and gas hydrates, or in the remobilization of material
from descending lithospheric plates is just a selection of
important question. Origin and evolutionary history of
the deep biosphere and the influence of the marine environments on their abundance is to be addressed for understanding the evolution of ancient life on Earth and will
provide analogs for comparative cosmological studies.
The crucial scientific problems and pathways to solution
have been described as key topics in the science plans of
444
MARINE GEOSCIENCES: A SHORT, ECCLECTIC AND WEIGHTED HISTORIC ACCOUNT