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| Titel |
Nature of orogenesis and volcanism in the Caucasus region based on results of regional tomography |
| VerfasserIn |
I. Koulakov, I. Zabelina, I. Amanatashvili, V. Meskhia |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1869-9510
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| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 3, no. 2 ; Nr. 3, no. 2 (2012-10-17), S.327-337 |
| Datensatznummer |
250000991
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| Publikation (Nr.) |
 copernicus.org/se-3-327-2012.pdf |
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| Zusammenfassung |
| In the paper, we discuss the problem of continental collision and related
volcanism in the Caucasus and surrounding areas based on the analysis of the
upper mantle seismic structure in a recently derived model by Koulakov (2011). This model, which includes P and S-velocity anomalies down to 1000 km depth,
was obtained from tomographic inversion of worldwide travel time
data from the catalogue of the International Seismological Center. It can be
seen that the Caucasus region is squeezed between two continental plates,
Arabian to the south and European to the north, which are displayed in the
tomographic model as high-velocity bodies down to about 200–250 km depth. On
the contrary, a very bright low-velocity anomaly beneath the collision area
implies that the lithosphere in this zone is very thin, which is also
supported by strong horizontal deformations and crustal thickening
indicating weak properties of the lithosphere. In the contact between stable
continental and collision zones, we observe a rather complex alternation of
seismic anomalies having the shapes of sinking drops. We propose that the
convergence process causes crustal thickening and transformation of the
lower crust material into the dense eclogite. When achieving a critical
mass, the dense eclogitic drops trigger detachment of the mantle lithosphere
and its delamination. The observed high-velocity bodies in the upper mantle
may indicate the parts of the descending mantle lithosphere which were
detached from the edges of the continental lithosphere plates. Very thin, or
even absent, mantle parts of the lithosphere leads to the presence of hot
asthenosphere just below the crust. The crustal shortening and
eclogitisation of the lower crustal layer leads to the dominantly felsic
composition of the crust which is favourable for the upward heat transport
from the mantle. This, and also the factors of frictional heating and the
radioactivity of felsic rocks, may be the origin of volcanic centres
in the Caucasus and surrounding collisional areas. |
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