Small-scale convection produces sedimentary sequences
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Інститут геофізики ім. С.I. Субботіна НАН України
2010
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| Zitieren: | Small-scale convection produces sedimentary sequences / S. Nielsen, K. Petersen, O. Clausen, R. Stephenson, T. Gerya // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 123-124. — Бібліогр.: 1 назв. — англ. |
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irk-123456789-1021322016-06-11T03:02:07Z Small-scale convection produces sedimentary sequences Nielsen, S. Petersen, K. Clausen, O. Stephenson, R. Gerya, T. 2010 Article Small-scale convection produces sedimentary sequences / S. Nielsen, K. Petersen, O. Clausen, R. Stephenson, T. Gerya // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 123-124. — Бібліогр.: 1 назв. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/102132 en Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
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Article |
| author |
Nielsen, S. Petersen, K. Clausen, O. Stephenson, R. Gerya, T. |
| spellingShingle |
Nielsen, S. Petersen, K. Clausen, O. Stephenson, R. Gerya, T. Small-scale convection produces sedimentary sequences Геофизический журнал |
| author_facet |
Nielsen, S. Petersen, K. Clausen, O. Stephenson, R. Gerya, T. |
| author_sort |
Nielsen, S. |
| title |
Small-scale convection produces sedimentary sequences |
| title_short |
Small-scale convection produces sedimentary sequences |
| title_full |
Small-scale convection produces sedimentary sequences |
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Small-scale convection produces sedimentary sequences |
| title_full_unstemmed |
Small-scale convection produces sedimentary sequences |
| title_sort |
small-scale convection produces sedimentary sequences |
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Інститут геофізики ім. С.I. Субботіна НАН України |
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2010 |
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http://dspace.nbuv.gov.ua/handle/123456789/102132 |
| citation_txt |
Small-scale convection produces sedimentary sequences / S. Nielsen, K. Petersen, O. Clausen, R. Stephenson, T. Gerya // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 123-124. — Бібліогр.: 1 назв. — англ. |
| series |
Геофизический журнал |
| work_keys_str_mv |
AT nielsens smallscaleconvectionproducessedimentarysequences AT petersenk smallscaleconvectionproducessedimentarysequences AT clauseno smallscaleconvectionproducessedimentarysequences AT stephensonr smallscaleconvectionproducessedimentarysequences AT geryat smallscaleconvectionproducessedimentarysequences |
| first_indexed |
2025-07-07T11:53:05Z |
| last_indexed |
2025-07-07T11:53:05Z |
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1836988977445339136 |
| fulltext |
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Small-scale convection produces sedimentary sequences
S. Nielsen1, K. Petersen1, O. Clausen1, R. Stephenson2, T. Gerya3, 2010
1Aarhus University, Department of Earth Sciences, Denmark
sbn@geo.au.dk
kenni@geo.au.dk
orc@geo.au.dk
2Geology and Petroleum Geology, School of Geosciences, College of Physical Sciences, Meston
Building, King’s College, Aberdeen, Scotland
r.stephenson@abdn.ac.uk
3Department of Geosciences, ETH-Zürich, Zürich, Switzerland
taras.gerya@erdw.ethz.ch
It is generally acknowledged that heat transfer
in the sub-lithospheric mantle is dominated by con-
vection that maintains an adiabatic temperature gra-
dient close to 0.6 K/km. Transfer of the advected
heat to the conductive lithosphere takes place at
the base of the lithosphere, which is maintained at
a relatively constant temperature in the vicinity of
1300 C. However, the thermo-mechanical details
of this highly dynamic boundary condition at the
base of the lithosphere are frequently approximated
by a fixed temperature at the assumed long-term
equilibrium depth of the base of the lithosphere (the
plate model). The present contribution investigates
this approximation. We apply a two-dimensional,
numerical, thermo-mechanical model of the lithos-
phere and upper mantle [Petersen, 2010] to asses
the effects resulting from a more correct represen-
tation of the sub-lithospheric small-scale convec-
tion, which is responsible for heat transfer in the
sub-lithospheric mantle. Given a particular mantle
rheology, our model shows small-scale convection,
and converges over time towards a self-consistent,
quasi-steady-state with a stable lithosphere, the
thickness of which depends on the chosen creep
parameters (within experimental constraints)
and hence on the vigour of small scale convection
and the heat transfer. At the base of the long term
stable litho-sphere, a thermal boundary layer is
formed in which the heat exchange between the
convecting sub-litho-spheric mantle and the
lithosphere takes place. Small ascending diapers of
warmer material slow down and spread out laterally
at the base of the lithosphere, pealing off colder
material that descends back into the upper
mantle. The buoyancy effects of this partly chaotic
mass movements cause low-amplitude and
relatively rapid vertical movements of the surface
of the lithosphere, which show only limited
horizontal correlation. The faster vertical
movements occur with periods from 2—20 Myr
and have amplitudes up to 20—40 m. Long term
surface movements have higher amplitudes and are
caused by quasi-static organisa-tion of the
convective pattern in the sub-lithospheric mantle,
which last long enough to influence the ther-mal
state of the lithosphere. Because of the visco-
elastic nature of the lithosphere, the more rapid
buoy-ancy changes are filtered by a stiffer
lithosphere than long term buoyancy changes.
The shorter periods therefore correlate for slightly
larger distances.
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much like the well-known plate model. However, in contrast to the plate model, the elevated astheno-
sphere is not instantaneously decoupled from the convecting upper mantle below, and cooling is thus
not entirely conductive above the former base of the lithosphere. This causes significantly protracted
cooling and slower and more linear post-rift subsi-dence. This model exhibits improved consistency
with subsidence data from several rifted margins and intra-continental basins. Because of the small scale
convection the long-term subsidence pattern in the presence of small-scale convection is superimposed
by the aforementioned low-amplitude vertical move-ments due to convection dynamics at the base of
the lithosphere. These movements are a recurrent and a potential cause for the development of strati-
graphic sequences at similar time scale. Such se-quences are commonly assumed to be caused by
eustatic variations. The results therefore have im-portant implications for inferences on global eustat-ic
variations inferred form sedimentary sequences by e.g. back stripping analyses and assumptions
about the thermal subsidence history based on the plate model of lithospheric cooling. Our results are
furthermore important for the assessment of hydro-carbon potential of sedimentary basins in terms of
stratigraphic correlation and thermal maturation. Extension of the convecting equilibrium model causes
fault-controlled continental rifting and sub-sidence, followed by protracted thermal subsidence,
Petersen K. Continental rifting in the presence of
small-scale convection — subsidence, strati-
graphy and upper mantle strength: PhD-thesis,
Aarhus University, 2010.
References
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