Davis, G. H., 1983. Shear-zone model for the origin of metamorphic
core complexes. Geology, 11, 342–347.
Deckert, H., Ring, U., and Mortimer, N., 2002. Tectonic significance of Cretaceous bivergent extensional shear zones in the
Torlesse accretionary wedge, central Otago Schist, New
Zealand. New Zealand Journal Geology and Geophysics, 45,
537–547.
Fitzgerald, P. G., Reynolds, S. J., Stump, E., Foster, D. A., and
Gleadow, A. J. W., 1993. Thermochronologic evidence for
timing of denudation and rate of crustal extension of the south
mountains metamorphic core complex and sierra estrella, Arizona. International Journal of Radiation Applications and
Instrumentation, 21, 555–563.
Foster, D. A., and John, B. E., 1999. Quantifying tectonic exhumation in an extensional orogen with thermochronology: examples
from the southern Basin and Range Province. Geological Society
Special Publication, 154, 343–364, doi:10.1144/GSL.
SP.1999.154.01.16.
Gans, P., 1987. An open-system two-layer crustal stretching model
for the eastern Great Basin. Tectonics, 6, 1–12.
Gessner, K., Ring, U., Johnson, C., Hetzel, R., Passchier, C. W., and
Güngör, T., 2001. An active bivergent rolling-hinge detachment
system: the Central Menderes metamorphic core complex in
western Turkey. Geology, 29, 611–614.
Gessner, K., Wijns, C., and Moresi, L., 2007. A dynamic process
model for tectonic denudation of metamorphic core complexes.
Tectonics, 26.
John, B. E., and Foster, D. A., 1993. Structural and thermal constraints on the initiation angle of detachment faulting in the
southern Basin and Range: the Chemehuevi Mountains study.
Geological Society of America Bulletin, 105, 1091–1108.
Jolivet, L., and Brun, J.-P., 2010. Cenozoic geodynamic evolution
of the Aegean. International Journal of Earth Sciences, 99,
109–38.
Krabbendam, M., 2001. When the Wilson cycle breaks down: how
orogens can produce strong lithosphere and inhibit their future
reworking. Geological Society Special Publication, 184, 57–75.
Kumerics, C., Ring, U., Brichau, S., Glodny, J., and Monie, P.,
2005. The extensional Ikaria shear zone and associated brittle
detachments faults, Aegean Sea, Greece. Journalof the Geological Society London, 162, 701–721.
Lister, G. S., and Davis, G. A., 1989. The origin of metamorphic
core complexes and detachment faults formed during Tertiary
continental extension in the northern Colorado River region, U.S. Journal of Structural Geology, 11, 65–94, doi:10.1016/01918141(89)90036-9.
Reynolds, S. J., 1982. Geology and Geochronology of the South
Mountains, Central Arizona. Unpublished Ph.D dissertation,
University of Arizona, Tucson, Arizona.
Ring, U., Layer, P. W., and Reischmann, T., 2001. Miocene highpressure metamorphism in the Cyclades and Crete, Aegean
Sea, Greece: evidence for large-magnitude displacement on the
Cretan detachment. Geology, 29, 395–398.
Ring, U., Thomson, S. N., and Bröcker, M., 2003. Fast extension
but little exhumation: the Vari detachment in the Cyclades,
Greece. Geological Magazine, 140, 245–252.
Ring, U., Glodny, J., Thomson, S., and Will, T., 2010. The Hellenic
subduction system: High-pressure metamorphism, exhumation,
normal faulting and large-scale extension. Annual Review of
Earth and Planetary Sciences, 38, 45–76, doi:10.1146/
annurev.earth. 050708.170910.
Rosenbaum, G., and Lister, G. S., 2004. Neogene and Quaternary
rollback evolution of the Tyrrhenian Sea, the Apennines and
the Sicilian Maghrebides. Tectonics, 23, doi: 10.1029/
2003TC001518
Schulte, D. O., Ring, U., Thomson, S., Glodny, J., and Carrad, H.,
2014. Two-stage development of the Paparoa Metamorphic Core
Complex, West Coast, South Island, New Zealand: hot continental extension precedes seafloor spreading by ~25 Myr. Lithosphere, 6, 177–194, doi:10.1130/L348.1.
Thomson, S. N., and Ring, U., 2006. Thermochronologic evaluation of post-collision extension in the Anatolide Orogen, western
Turkey. Tectonics, 25, TC3005, 20 p, doi:10.1029/2005
TC001833.
Tucholke, B. E., Lin, J., and Kleinrock, M. C., 1998. Megamullions
and mullion structure defining oceanic metamorphic core complexes on the Mid-Atlantic Ridge. Journal of Geophysical
Research, B: Solid Earth, 103, 9857–9866.
Wernicke, B. P., 1981. Low-angle normal faults in the Basin and
Range Province-Nappe tectonics in an extending orogen.
Nature, 291, 645–648.
Cross-references
Magmatism at Convergent Plate Boundaries
Marginal Seas
Oceanic Rifts
Passive Plate Margins
Plate Tectonics
METHANE IN MARINE SEDIMENTS
Gerhard Bohrmann
1 and Marta E. Torres
2
1
MARUM-Center for Marine Environmental Sciences,
University of Bremen, Bremen, Germany
2
College of Earth, Ocean, and Atmospheric Sciences,
Oregon State University, Corvallis, OR, USA
Definition
Methane is the simplest hydrocarbon with the chemical
formula CH 4 . At room temperature and standard pressure,
methane is a colorless, odorless gas. It is the main component of natural gas and thus important as an energy source.
Due to its ability to absorb energy on the infrared band,
methane plays a direct role in the Earth’s greenhouse
effect.
Methane distribution
Methane represents a key component of the carbon cycle
in marine sediments. The amount of carbon that presently
occurs as methane in marine sediments is thought to be
~500–10,000 Gt (Kvenvolden and Lorenson, 2001;
Milkov, 2004; 1 Gt ¼ 10
15 g). The size of this reservoir
is ultimately determined by a balance of organic carbon
sources and sinks, which vary in time and space.
The loci of large methane deposits are further controlled
by thermal, lithological, and structural characteristics of
the sediments. Methane production is fundamentally controlled by organic carbon rain to the sediments, which in
turn depends on ocean productivity and water depths
(Suess, 1980). Only a fraction of the organic carbon that
reaches the seafloor is available for methane generation
at greater depth, because a significant part of the organic
carbon rain is already remineralized within the top meters
METHANE IN MARINE SEDIMENTS
495
core complexes. Geology, 11, 342–347.
Deckert, H., Ring, U., and Mortimer, N., 2002. Tectonic significance of Cretaceous bivergent extensional shear zones in the
Torlesse accretionary wedge, central Otago Schist, New
Zealand. New Zealand Journal Geology and Geophysics, 45,
537–547.
Fitzgerald, P. G., Reynolds, S. J., Stump, E., Foster, D. A., and
Gleadow, A. J. W., 1993. Thermochronologic evidence for
timing of denudation and rate of crustal extension of the south
mountains metamorphic core complex and sierra estrella, Arizona. International Journal of Radiation Applications and
Instrumentation, 21, 555–563.
Foster, D. A., and John, B. E., 1999. Quantifying tectonic exhumation in an extensional orogen with thermochronology: examples
from the southern Basin and Range Province. Geological Society
Special Publication, 154, 343–364, doi:10.1144/GSL.
SP.1999.154.01.16.
Gans, P., 1987. An open-system two-layer crustal stretching model
for the eastern Great Basin. Tectonics, 6, 1–12.
Gessner, K., Ring, U., Johnson, C., Hetzel, R., Passchier, C. W., and
Güngör, T., 2001. An active bivergent rolling-hinge detachment
system: the Central Menderes metamorphic core complex in
western Turkey. Geology, 29, 611–614.
Gessner, K., Wijns, C., and Moresi, L., 2007. A dynamic process
model for tectonic denudation of metamorphic core complexes.
Tectonics, 26.
John, B. E., and Foster, D. A., 1993. Structural and thermal constraints on the initiation angle of detachment faulting in the
southern Basin and Range: the Chemehuevi Mountains study.
Geological Society of America Bulletin, 105, 1091–1108.
Jolivet, L., and Brun, J.-P., 2010. Cenozoic geodynamic evolution
of the Aegean. International Journal of Earth Sciences, 99,
109–38.
Krabbendam, M., 2001. When the Wilson cycle breaks down: how
orogens can produce strong lithosphere and inhibit their future
reworking. Geological Society Special Publication, 184, 57–75.
Kumerics, C., Ring, U., Brichau, S., Glodny, J., and Monie, P.,
2005. The extensional Ikaria shear zone and associated brittle
detachments faults, Aegean Sea, Greece. Journalof the Geological Society London, 162, 701–721.
Lister, G. S., and Davis, G. A., 1989. The origin of metamorphic
core complexes and detachment faults formed during Tertiary
continental extension in the northern Colorado River region, U.S. Journal of Structural Geology, 11, 65–94, doi:10.1016/01918141(89)90036-9.
Reynolds, S. J., 1982. Geology and Geochronology of the South
Mountains, Central Arizona. Unpublished Ph.D dissertation,
University of Arizona, Tucson, Arizona.
Ring, U., Layer, P. W., and Reischmann, T., 2001. Miocene highpressure metamorphism in the Cyclades and Crete, Aegean
Sea, Greece: evidence for large-magnitude displacement on the
Cretan detachment. Geology, 29, 395–398.
Ring, U., Thomson, S. N., and Bröcker, M., 2003. Fast extension
but little exhumation: the Vari detachment in the Cyclades,
Greece. Geological Magazine, 140, 245–252.
Ring, U., Glodny, J., Thomson, S., and Will, T., 2010. The Hellenic
subduction system: High-pressure metamorphism, exhumation,
normal faulting and large-scale extension. Annual Review of
Earth and Planetary Sciences, 38, 45–76, doi:10.1146/
annurev.earth. 050708.170910.
Rosenbaum, G., and Lister, G. S., 2004. Neogene and Quaternary
rollback evolution of the Tyrrhenian Sea, the Apennines and
the Sicilian Maghrebides. Tectonics, 23, doi: 10.1029/
2003TC001518
Schulte, D. O., Ring, U., Thomson, S., Glodny, J., and Carrad, H.,
2014. Two-stage development of the Paparoa Metamorphic Core
Complex, West Coast, South Island, New Zealand: hot continental extension precedes seafloor spreading by ~25 Myr. Lithosphere, 6, 177–194, doi:10.1130/L348.1.
Thomson, S. N., and Ring, U., 2006. Thermochronologic evaluation of post-collision extension in the Anatolide Orogen, western
Turkey. Tectonics, 25, TC3005, 20 p, doi:10.1029/2005
TC001833.
Tucholke, B. E., Lin, J., and Kleinrock, M. C., 1998. Megamullions
and mullion structure defining oceanic metamorphic core complexes on the Mid-Atlantic Ridge. Journal of Geophysical
Research, B: Solid Earth, 103, 9857–9866.
Wernicke, B. P., 1981. Low-angle normal faults in the Basin and
Range Province-Nappe tectonics in an extending orogen.
Nature, 291, 645–648.
Cross-references
Magmatism at Convergent Plate Boundaries
Marginal Seas
Oceanic Rifts
Passive Plate Margins
Plate Tectonics
METHANE IN MARINE SEDIMENTS
Gerhard Bohrmann
1 and Marta E. Torres
2
1
MARUM-Center for Marine Environmental Sciences,
University of Bremen, Bremen, Germany
2
College of Earth, Ocean, and Atmospheric Sciences,
Oregon State University, Corvallis, OR, USA
Definition
Methane is the simplest hydrocarbon with the chemical
formula CH 4 . At room temperature and standard pressure,
methane is a colorless, odorless gas. It is the main component of natural gas and thus important as an energy source.
Due to its ability to absorb energy on the infrared band,
methane plays a direct role in the Earth’s greenhouse
effect.
Methane distribution
Methane represents a key component of the carbon cycle
in marine sediments. The amount of carbon that presently
occurs as methane in marine sediments is thought to be
~500–10,000 Gt (Kvenvolden and Lorenson, 2001;
Milkov, 2004; 1 Gt ¼ 10
15 g). The size of this reservoir
is ultimately determined by a balance of organic carbon
sources and sinks, which vary in time and space.
The loci of large methane deposits are further controlled
by thermal, lithological, and structural characteristics of
the sediments. Methane production is fundamentally controlled by organic carbon rain to the sediments, which in
turn depends on ocean productivity and water depths
(Suess, 1980). Only a fraction of the organic carbon that
reaches the seafloor is available for methane generation
at greater depth, because a significant part of the organic
carbon rain is already remineralized within the top meters
METHANE IN MARINE SEDIMENTS
495