Mapping and Analyzing the Volcano-Petrology and Tectono-Seismicity Characteristics Along the Syrian Rift – NW the Arabian Plate - Advances in Data, Methods, Models and Their Applications in Geoscience - page 158

5. Conclusion
The Syrian rift is a world structure, and constitute the north part of the Dead Sea Fault Zone
(DSFZ).Structural analysis using variable techniques attest that many faults have recently or
are still active to occuresent along the Syrian rift. This is notably indicated by two
phenomena: volcanism and seismicity.
The composition of the underlying lithospheric mantle points to a complex history
involving polybaric partial melting at various degrees, starting in the garnet - and
proceeding in the spinel stability field. Some clinopyroxenes at least record mantle
metasomatism, caused by ephemeral carbonate magmas or percolating basalting melts
issued from a mantle plume under the Arabic plate.
Most major seisms in Syria occur in two zones (Fig.14): with the rift zone, in a North - South
direction, but not exactly along the fractures. Most epicenters occur westward along the
coast or in the sea. The other zone is SW - NE oriented, along the Damascus Palmyra
mountain chain. It does not seem to be related to any volcanic activity, but corresponds
namely to superficial deformation of the sedimentary cover.
For volcanic-related seismicity, Petrological data from volcanic xenoliths have identified the
existence of a hot spot (plume), under the Syrian rift. In the earliest period of volcanic
activity (Cretaceous), this plume started at the level of mantel garnet peridotite, leading to a
marked explosive volcanism. It may be hypothesized that this type of volcanism did
correspond to major seismicity. In more recent time, the plume head tends to rise, while at
the same time migrating towards the West. This was accompanied by a more effusive type
of volcanism, associated to the moderate seismicity, presently shown. The last eruption
(10.000 y) occurred in the large volcanic massif at the South (Djebel Al Arab). With one
exception, no major seism relates to this last eruption. This recent massif, by far the larger in
Syria, seems to distantiate from the rift zone, at the difference, notably, of older Cretaceous
volcanism.
At the scale of the human observation, the seismicity does not seem to be directly related to
present-day volcanic activity.Either reminiscence of ancient volcanism, or consequence of
superficial deformation. Both phenomena tend to fade out with time, in line with the
decrease of major seismic intensity which has occurred during the last millennium.
6. References
Adiyaman, O. and Chorowicz, J. (2002)-Late Cenozoic tectonics and volcanism in the
northwestern corner of the Arabian plate:a consequence of the strik-slip Dead Sea
Fault Zone and lateral escape of Anatolia. Journal of Volcanologyand Geothermal
Research , 117, 327-345.
Al Abdalla, A. (2008)- Evolution tectonique de la plat-form Arabe en Syrie depuis le Mesozoique .
These Doctorat, Universite Pierre et Marie Curie.302p.
Al Damegh, K; Sandvol, and Barazangi, M. (2005) - Crustal structure of the Arabian Plate:
New constraints from the analysis of teleseismic receiver functions. Earth and
Planeta Sciences Letters , 231, 9, p. 177-196. Contrib. Mineral.Petrol. 50: 79-92.
Al Mishwat, AT. and Nasir, SJ. (2004)- Composition of the lower crust of the Arabian plate: a
xenolith perspective. Lithos , 72: 45-48.;
Al-Tarazi, E. (1999)- Regional seismic hazard study for the eastern Mediterranean (Trans-
Jordan, Levant and Antakia) and Sinai Region. J. of African Earth Sciences, vol. n°3,
743-750.