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| Titel |
Distributed and localized horizontal tectonic deformation as inferred from drainage network geometry and topology: A case study from Lebanon |
| VerfasserIn |
Liran Goren, Sebastien Castelltort, Yann Klinger |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250127581
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| Publikation (Nr.) |
 EGU/EGU2016-7473.pdf |
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| Zusammenfassung |
| Partitioning of horizontal deformation between localized and distributed modes in regions of
oblique tectonic convergence is, in many cases, hard to quantify. As a case study, we consider
the Dead Sea Fault System that changes its orientation across Lebanon and forms a
restraining bend. The oblique deformation along the Lebanese restraining bend is
characterized by a complex suite of tectonic structures, among which, the Yammouneh
fault, is believed to be the main strand that relays deformation from the southern
section to the northern section of the Dead Sea Fault System. However, uncertainties
regarding slip rates along the Yammouneh fault and strain partitioning in Lebanon still
prevail.
In the current work we use the geometry and topology of river basins together with numerical
modeling to evaluate modes and rates of the horizontal deformation in Mount Lebanon that is
associated with the Arabia-Sinai relative plate motion. We focus on river basins that drain
Mount Lebanon to the Mediterranean and originate close to the Yammouneh fault.
We quantify a systematic counterclockwise rotation of these basins and evaluate
drainage area disequilibrium using an application of the χ mapping technique, which
aims at estimating the degree of geometrical and topological disequilibrium in river
networks. The analysis indicates a systematic spatial pattern whereby tributaries of the
rotated basins appear to experience drainage area loss or gain with respect to channel
length.
A kinematic model that is informed by river basin geometry reveals that since the late
Miocene, about a quarter of the relative plate motion parallel to the plate boundary has been
distributed along a wide band of deformation to the west of the Yammouneh fault. Taken
together with previous, shorter-term estimates, the model indicates little variation
of slip rate along the Yammouneh fault since the late Miocene. Kinematic model
results are compatible with late Miocene paleomagnetic rotations in western Mount
Lebanon. A numerical landscape evolution experiment demonstrates the emergence
of a similar χ pattern of drainage area disequilibrium in response to progressive
distributed shear deformation of river basins with relatively minor drainage network
reorganization. |
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