construction, oil and gas exploration, fisheries, and possible deep-sea mining for metals, can have a great impact on
sediment mobilization and transport and on the ecosystems in general. Our present understanding of the complex
sedimentation processes and ecosystems on continental
margins is not sufficient, and integrated studies using
modern technologies for observation and modeling are
needed.
Bibliography
Freiwald, A., and Roberts, J. M. (eds.), 2005. Cold-Water Corals
and Ecosystems. Berlin/Heidelberg: Springer.
Krastel, S., Lehr, J., Winkelmann, D., Schwenk, T., Preu, B.,
Strasser, M., Wynn, R. B., Georgiopoulou, A., and Hanebuth,
T. J. J., 2014. Mass wasting along Atlantic continental margins:
a comparison between NW-Africa and the de la Plata River
region (northern Argentina and Uruguay). In Krastel, S.,
et al. (eds.), Submarine Mass Movements and Their Consequences. Advances in Natural and Technological Hazards
Research. Dordrecht: Springer, Vol. 37, pp. 459–469.
Seibold, E., and Berger, W., 1996. The Sea Floor. Berlin/Heidelberg: Springer.
Tarbuck, E. J., and Lutgens, F. K., 2009. Earth Science. Upper Saddle River: Pearson Prentice-Hall.
Wefer, G., Billet, D., Hebbeln, D., Jørgensen, B. B., and van
Weering, T. (eds.), 2002. Ocean Margin Systems. Berlin/Heidelberg: Springer.
Cross-references
Active Continental Margins
Coasts
Cold Seeps
Contourites
Deep-sea Sediments
Marine Gas Hydrates
Mass Wasting
Methane in Marine Sediments
Passive Plate Margins
Reefs (Biogenic)
Turbidites
OCEANIC PLATEAUS
Andrew C. Kerr
School of Earth and Ocean Sciences, Cardiff University,
Cardiff, Wales, UK
Definition
Oceanic plateaus are large areas of elevated, overthickened basaltic ocean floor (>5 Â 10
5 km
3
) which have
formed throughout most of Earth’s history, and, unlike
most oceanic crust, they are not primarily the result of seafloor spreading processes and melting of ambient upper
mantle but rather are widely regarded to have been formed
by decompression melting of hot mantle plumes (Kerr,
2014).
Introduction
The vast erupted and intruded volume of oceanic plateaus
means that they are classed as large igneous provinces
(LIPs), along with continental flood basalts and volcanic
rifted margins. The term large igneous provinces was originally proposed by Coffin and Eldholm (1992) as a generic
term for igneous provinces with a volume exceeding 0.1 Â
10
6 km
2 (see also Coffin and Eldholm 2005). More
recently, this definition has been revised by Bryan and
Ernst (2008), who proposed a classification scheme that
includes giant radiating dike swarms and silicic LIPs.
Bryan and Ernst’s formal definition is as follows
LIPs are magmatic provinces with areal extents >0.1 Â
10
6 km
2
, igneous volumes >0.1 Â 10
6 km
3 and maximum
lifespans of ~50 m.y. that have intraplate tectonic settings
or geochemical affinities, and are characterised by igneous
pulse(s) of short duration (~1–5 m.y.), during which a large
proportion (>75 %) of the total igneous volume has been
emplaced.
In the early 1970s, new evidence from seismic surveys
revealed that several large portions of the ocean floor were
much thicker than “normal” oceanic crust (6–7 km) (see
Layering of Oceanic Crust). One of the first areas of such
over-thickened crust to be identified was the Caribbean
Plate which Donnelly (1973) proposed to be an “oceanic
flood basalt province.” The term “oceanic plateau” was
first used by Kroenke (1974) to describe the large area of
thickened crust (>30 km) and then recently discovered
in the Western Pacific and now known as the Ontong Java
Plateau.
The thick crustal sections and elevated topography of
oceanic plateaus (generally 2–3 km above the surrounding
ocean floor) result in them being more buoyant than normal oceanic crust. Thick oceanic plateaus and those that
are relatively young when they interact with subduction
zones are therefore difficult to subduct (e.g., Cloos,
1993; Tetreault and Buiter, 2012). The resultant collision
of thick, buoyant oceanic crust with subduction zones
results in extensive oceanic plateau fragments being preserved in accreted terrains (see below). These accreted
oceanic plateaus are more likely to be preserved in the
geological record than continental flood basalts that are
more easily eroded by subaerial processes, and so oceanic
plateaus could have been major contributors to the growth
of continental crust throughout Earth’s history (Kerr and
Mahoney, 2007).
As our knowledge of the ocean basins and accreted terrains has improved over the last 30 years, many more oceanic plateaus have been identified, both relatively recent
“in situ” plateaus (Figure 1) and older accreted examples.
Characteristics of oceanic plateaus
The three best-known extant (i.e., still predominantly in
the oceanic realm and not accreted) oceanic plateaus are
the Ontong Java, Kerguelen, and Caribbean–Colombian
plateaus (Figure 1). The following sections will mostly
558
OCEANIC PLATEAUS
sediment mobilization and transport and on the ecosystems in general. Our present understanding of the complex
sedimentation processes and ecosystems on continental
margins is not sufficient, and integrated studies using
modern technologies for observation and modeling are
needed.
Bibliography
Freiwald, A., and Roberts, J. M. (eds.), 2005. Cold-Water Corals
and Ecosystems. Berlin/Heidelberg: Springer.
Krastel, S., Lehr, J., Winkelmann, D., Schwenk, T., Preu, B.,
Strasser, M., Wynn, R. B., Georgiopoulou, A., and Hanebuth,
T. J. J., 2014. Mass wasting along Atlantic continental margins:
a comparison between NW-Africa and the de la Plata River
region (northern Argentina and Uruguay). In Krastel, S.,
et al. (eds.), Submarine Mass Movements and Their Consequences. Advances in Natural and Technological Hazards
Research. Dordrecht: Springer, Vol. 37, pp. 459–469.
Seibold, E., and Berger, W., 1996. The Sea Floor. Berlin/Heidelberg: Springer.
Tarbuck, E. J., and Lutgens, F. K., 2009. Earth Science. Upper Saddle River: Pearson Prentice-Hall.
Wefer, G., Billet, D., Hebbeln, D., Jørgensen, B. B., and van
Weering, T. (eds.), 2002. Ocean Margin Systems. Berlin/Heidelberg: Springer.
Cross-references
Active Continental Margins
Coasts
Cold Seeps
Contourites
Deep-sea Sediments
Marine Gas Hydrates
Mass Wasting
Methane in Marine Sediments
Passive Plate Margins
Reefs (Biogenic)
Turbidites
OCEANIC PLATEAUS
Andrew C. Kerr
School of Earth and Ocean Sciences, Cardiff University,
Cardiff, Wales, UK
Definition
Oceanic plateaus are large areas of elevated, overthickened basaltic ocean floor (>5 Â 10
5 km
3
) which have
formed throughout most of Earth’s history, and, unlike
most oceanic crust, they are not primarily the result of seafloor spreading processes and melting of ambient upper
mantle but rather are widely regarded to have been formed
by decompression melting of hot mantle plumes (Kerr,
2014).
Introduction
The vast erupted and intruded volume of oceanic plateaus
means that they are classed as large igneous provinces
(LIPs), along with continental flood basalts and volcanic
rifted margins. The term large igneous provinces was originally proposed by Coffin and Eldholm (1992) as a generic
term for igneous provinces with a volume exceeding 0.1 Â
10
6 km
2 (see also Coffin and Eldholm 2005). More
recently, this definition has been revised by Bryan and
Ernst (2008), who proposed a classification scheme that
includes giant radiating dike swarms and silicic LIPs.
Bryan and Ernst’s formal definition is as follows
LIPs are magmatic provinces with areal extents >0.1 Â
10
6 km
2
, igneous volumes >0.1 Â 10
6 km
3 and maximum
lifespans of ~50 m.y. that have intraplate tectonic settings
or geochemical affinities, and are characterised by igneous
pulse(s) of short duration (~1–5 m.y.), during which a large
proportion (>75 %) of the total igneous volume has been
emplaced.
In the early 1970s, new evidence from seismic surveys
revealed that several large portions of the ocean floor were
much thicker than “normal” oceanic crust (6–7 km) (see
Layering of Oceanic Crust). One of the first areas of such
over-thickened crust to be identified was the Caribbean
Plate which Donnelly (1973) proposed to be an “oceanic
flood basalt province.” The term “oceanic plateau” was
first used by Kroenke (1974) to describe the large area of
thickened crust (>30 km) and then recently discovered
in the Western Pacific and now known as the Ontong Java
Plateau.
The thick crustal sections and elevated topography of
oceanic plateaus (generally 2–3 km above the surrounding
ocean floor) result in them being more buoyant than normal oceanic crust. Thick oceanic plateaus and those that
are relatively young when they interact with subduction
zones are therefore difficult to subduct (e.g., Cloos,
1993; Tetreault and Buiter, 2012). The resultant collision
of thick, buoyant oceanic crust with subduction zones
results in extensive oceanic plateau fragments being preserved in accreted terrains (see below). These accreted
oceanic plateaus are more likely to be preserved in the
geological record than continental flood basalts that are
more easily eroded by subaerial processes, and so oceanic
plateaus could have been major contributors to the growth
of continental crust throughout Earth’s history (Kerr and
Mahoney, 2007).
As our knowledge of the ocean basins and accreted terrains has improved over the last 30 years, many more oceanic plateaus have been identified, both relatively recent
“in situ” plateaus (Figure 1) and older accreted examples.
Characteristics of oceanic plateaus
The three best-known extant (i.e., still predominantly in
the oceanic realm and not accreted) oceanic plateaus are
the Ontong Java, Kerguelen, and Caribbean–Colombian
plateaus (Figure 1). The following sections will mostly
558
OCEANIC PLATEAUS