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| Titel |
First results of 2D Thermo-mechanical modelling of Cenozoic lithospheric deformation in the Himalaya-Tibet-Pamir-Tien Shan orogen |
| VerfasserIn |
Jens Tympel, Stephan Sobolev |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053518
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| Zusammenfassung |
| Earth’s most impressive and frequently studied orogeny, which was induced by
the ongoing continent-continent collision of India and Eurasia, is the Himalayan
orogeny. The collision, starting at around 55 Ma gave rise to the Tibetan plateau,
the largest highest plateau of the world, with an average elevation exceeding 5000
m.
One of the mountain ranges of the Himalayan-Tibet orogenic belt is the Pamir-Tien Shan,
which accumulates the largest strain of the entire orogenic system and hosts the Earth‘s most
important active intra-continental subduction zone. The Tien Shan and Pamir collision zones
are studied by a series of geophysical experiments within the framework of the
multi-disciplinary Tien Shan - Pamir Geodynamic Program.
As participants of the program, our aim is to find controlling factors for
continent-continent collisions with the help of 2D (and later on 3D) thermo-mechanical
models and to integrate the geologic-geophysical work of TIPAGE. For this approach the
finite-element code SLIM3D (Popov and Sobolev, 2008) is used, which allows coupled
thermo-mechanical treatment of deformation processes and is capable of highly
non-linear visco-elasto-plastic rheology, allowing self-consistent generation of faults as
well.
We hereby present our current model setup which is used to study the initiation of
intra-continental subduction. The size of the model is 3000 km N-S and 400 km in depth with
a resolution of 5 km. Given that our experiments are starting at 45 Ma and the postcollision
shortening within Asia is well beyond 1000 km, we are using the “moving window”
technique which has been used before in (Sobolev and Babeyko, 2006) to follow the center of
collision, while the Indian plate is advancing.
The Indian plate in our model consists of a strong central part, plus a postulated northern
extension which is weaker and already subducted in present time.
We will be running different model setups for N-S cross sections in the Pamir region of
Eurasia, including sections through the major tectonic features, the Tajik basin and the strong
archean Tarim block. The latter one will be studied in several section with different versions
of size, growing larger from west to east.
Boundary condition for the left side are dynamic-velocity values taken from
paleoreconstructions in (Molnar and Stock, 2009) while the right side is closed and free slip
condition is applied. The bottom of the model has been left open and true free surface is
applied on top.
We also implemented gabbro-eclogite, coesite-stishovite phase transitions which are
playing an important role in the lower crust of the upper plate and in the crust of the
subducting plate, respectively. We also applied a realistic rheology which is constantly
adjusted to recent research results.
The experiments are performed at the moment and their results will be presented at the
EGU.
In future another major aim is to include erosion and sedimentation routines in the model,
given that climate has a profound effect on tectonics which seem to be generally
underestimated. This will be done with the help of a new 2D-erosioncode which is currently
in development as part of the Theme (II) (CRP-collaborative research project 6) inside
TIPAGE. |
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