Hedges, J. I., Keil, R., and Benner, R., 1997. What happens to terrestrial organic matter in the ocean? Organic Geochemistry, 27,
195–212.
Lisitzin, A. P., 2004. Sediment fluxes, natural filtration, and sedimentary systems of a “living ocean”. Russian Geology and Geophysics, 45, 12–43.
Romankevich, E. A., 1984. Biogeochemistry of Organic Matter in
the Ocean. Berlin: Springer, p. 334.
Romankevich, E. A., and Vetrov, A. A., 2013. Masses of carbon in
the Earth’s hydrosphere. Geochemistry International, 51,
431–455.
Stein, R., and Macdonald, R. W. (eds.), 2004. The Organic Carbon
Cycle in the Arctic Ocean. Berlin: Springer. 363 p.
Suess, E., 1980. Particulate organic carbon flux in the oceans – surface productivity and oxygen utilization. Nature, 288, 260–263.
Thomas, D. N., Papadimitriou, S., and Michel, C., 2010. Biogeochemistry of sea ice. In Dieckmann, G. S., and Thomas, D. N.
(eds.), Sea Ice. Oxford, Ames: Wiley-Blackwell, pp. 425–467.
Cross-references
Anoxic Oceans
Chemosynthetic Life
Cold Seeps
Deep-sea Sediments
Diatoms
Energy Resources
Estuary, Estuarine Hydrodynamics
Marine Gas Hydrates
Methane in Marine Sediments
Radiocarbon: Clock and Tracer
Sapropels
Turbidites
OROGENY
Bernhard Grasemann and Benjamin Huet
Department for Geodynamics and Sedimentology,
University of Vienna, Wien, Austria
Synonyms
Orogens: orogenic belts, mountain belts; Orogeny: mountain building, formation of orogens
Definition
Orogeny, from the Greek ὅrοB (óros) “mountain” and
gέnesiB (ge ´nesis) “creation,” refers to the geodynamic
processes leading to deformation of the Earth lithosphere
resulting in crustal thickening, surface uplift, and the formation of large-scale topography rising more or less
abruptly from the surrounding level.
Introduction
Orogenic belts are large mountain belts forming usually at
destructive plate boundaries, as part of an orogenic cycle.
They record a number of complex geodynamic processes,
often associated with subduction of an oceanic plate
beneath another tectonic plate, which is eventually
followed by collision between two continents or between
a continent and an island arc. Contrary to the continental
crust, which is thick (generally >30 km) and buoyant
(density ~2,700 kg m
À3
), the oceanic crust is thin
(generally <10 km) and dense (density ~2,900 kg m
À3
).
It can be easily recycled into the mantle during subduction, due to its transformation to very dense eclogite
(density >3,300 kg m
À3
). Since subduction has been consuming oceanic lithosphere through the Earth history,
almost no oceanic crust older than ~180 Ma (lower Jurassic) exists. Orogenic belts represent thus important
archives for more than 95 % of the Earth history
(Figure 1).
The formation of mountain belts has induced major
environmental and climatic global changes during the
Earth history, through modifying the atmospheric and oceanic circulations, the location of elevated terrains suitable
for inland ice, the radiation balance, and the geochemical
cycles. The present-day orogenic belts are associated with
active tectonics and volcanism which manifest them by
potentially deadly geological hazards (earthquakes, landslides, and volcanic eruptions). Understanding the formation and the destruction of orogens at both short and long
term is, therefore, essential.
Although orogens are generally considered to form at
destructive plate boundaries, it is important to note that
deformation of the lithosphere and its resulting topography may develop in other geodynamic environments:
along constructive plate boundaries (e.g., East African
Rift), extensional orogens (e.g., Canadian Cordillera),
along conservative plate boundaries (e.g., Dead Sea
Transform fault system), and above hot spots (e.g., Hawaiian–Emperor Seamount Chain).
The orogenic cycle
The Canadian geologist John Tuzo Wilson (1908–1993)
described the periodic opening and closing of oceans giving rise to the formation of orogens as the orogenic cycle
(sometimes called “Wilson Cycle” or “supercontinent
cycle”). Each stage of such a cycle combines a number
of different geodynamic processes (Moores and Twiss,
1995). For example, deep tectonic processes controlling
the formation and the destruction of an orogen are always
associated with erosion and sedimentation, which act at
the surface (England and Molnar, 1990; Avouac and
Burov, 1996).
There are four characteristic stages in an orogenic
cycle:
(i) Continental rifting and opening of a new oceanic
basin. Thick shallow-water sediments accumulate
along the margin of an oceanic basin. In the more
central parts of the basin, deep-water sediments are
deposited on top of basaltic flows and gabbroic intrusions forming at the mid-ocean ridge.
(ii) Subduction of the oceanic lithosphere initiates along a
ridge-parallel fault, an oceanic fracture zone, a transform fault, or an ocean–continent transition. It may
be associated with the obduction of oceanic
602
OROGENY
195–212.
Lisitzin, A. P., 2004. Sediment fluxes, natural filtration, and sedimentary systems of a “living ocean”. Russian Geology and Geophysics, 45, 12–43.
Romankevich, E. A., 1984. Biogeochemistry of Organic Matter in
the Ocean. Berlin: Springer, p. 334.
Romankevich, E. A., and Vetrov, A. A., 2013. Masses of carbon in
the Earth’s hydrosphere. Geochemistry International, 51,
431–455.
Stein, R., and Macdonald, R. W. (eds.), 2004. The Organic Carbon
Cycle in the Arctic Ocean. Berlin: Springer. 363 p.
Suess, E., 1980. Particulate organic carbon flux in the oceans – surface productivity and oxygen utilization. Nature, 288, 260–263.
Thomas, D. N., Papadimitriou, S., and Michel, C., 2010. Biogeochemistry of sea ice. In Dieckmann, G. S., and Thomas, D. N.
(eds.), Sea Ice. Oxford, Ames: Wiley-Blackwell, pp. 425–467.
Cross-references
Anoxic Oceans
Chemosynthetic Life
Cold Seeps
Deep-sea Sediments
Diatoms
Energy Resources
Estuary, Estuarine Hydrodynamics
Marine Gas Hydrates
Methane in Marine Sediments
Radiocarbon: Clock and Tracer
Sapropels
Turbidites
OROGENY
Bernhard Grasemann and Benjamin Huet
Department for Geodynamics and Sedimentology,
University of Vienna, Wien, Austria
Synonyms
Orogens: orogenic belts, mountain belts; Orogeny: mountain building, formation of orogens
Definition
Orogeny, from the Greek ὅrοB (óros) “mountain” and
gέnesiB (ge ´nesis) “creation,” refers to the geodynamic
processes leading to deformation of the Earth lithosphere
resulting in crustal thickening, surface uplift, and the formation of large-scale topography rising more or less
abruptly from the surrounding level.
Introduction
Orogenic belts are large mountain belts forming usually at
destructive plate boundaries, as part of an orogenic cycle.
They record a number of complex geodynamic processes,
often associated with subduction of an oceanic plate
beneath another tectonic plate, which is eventually
followed by collision between two continents or between
a continent and an island arc. Contrary to the continental
crust, which is thick (generally >30 km) and buoyant
(density ~2,700 kg m
À3
), the oceanic crust is thin
(generally <10 km) and dense (density ~2,900 kg m
À3
).
It can be easily recycled into the mantle during subduction, due to its transformation to very dense eclogite
(density >3,300 kg m
À3
). Since subduction has been consuming oceanic lithosphere through the Earth history,
almost no oceanic crust older than ~180 Ma (lower Jurassic) exists. Orogenic belts represent thus important
archives for more than 95 % of the Earth history
(Figure 1).
The formation of mountain belts has induced major
environmental and climatic global changes during the
Earth history, through modifying the atmospheric and oceanic circulations, the location of elevated terrains suitable
for inland ice, the radiation balance, and the geochemical
cycles. The present-day orogenic belts are associated with
active tectonics and volcanism which manifest them by
potentially deadly geological hazards (earthquakes, landslides, and volcanic eruptions). Understanding the formation and the destruction of orogens at both short and long
term is, therefore, essential.
Although orogens are generally considered to form at
destructive plate boundaries, it is important to note that
deformation of the lithosphere and its resulting topography may develop in other geodynamic environments:
along constructive plate boundaries (e.g., East African
Rift), extensional orogens (e.g., Canadian Cordillera),
along conservative plate boundaries (e.g., Dead Sea
Transform fault system), and above hot spots (e.g., Hawaiian–Emperor Seamount Chain).
The orogenic cycle
The Canadian geologist John Tuzo Wilson (1908–1993)
described the periodic opening and closing of oceans giving rise to the formation of orogens as the orogenic cycle
(sometimes called “Wilson Cycle” or “supercontinent
cycle”). Each stage of such a cycle combines a number
of different geodynamic processes (Moores and Twiss,
1995). For example, deep tectonic processes controlling
the formation and the destruction of an orogen are always
associated with erosion and sedimentation, which act at
the surface (England and Molnar, 1990; Avouac and
Burov, 1996).
There are four characteristic stages in an orogenic
cycle:
(i) Continental rifting and opening of a new oceanic
basin. Thick shallow-water sediments accumulate
along the margin of an oceanic basin. In the more
central parts of the basin, deep-water sediments are
deposited on top of basaltic flows and gabbroic intrusions forming at the mid-ocean ridge.
(ii) Subduction of the oceanic lithosphere initiates along a
ridge-parallel fault, an oceanic fracture zone, a transform fault, or an ocean–continent transition. It may
be associated with the obduction of oceanic
602
OROGENY