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STT-01 General contributions to tectonics and structural geology - Part 2

 

Meso-Cenozoic tectonic evolution of the south-eastern Levant margin

 

Clément Hardy, Universite Pierre et Marie Curie (France)
Catherine Homberg, Universite Pierre et Marie Curie (France)
Yehuda Eyal, Ben-Gurion University of the Negev (Israel)
Eric Barrier, Universite Pierre et Marie Curie (France)
Carla Müller, Consultant (France)
 

 

We investigated the age and duration of each tectonic event that occurred in the southern Levant margin in Israel, between the southern segment of the Dead Sea transform to the east, and the Levantine basin to the west. We performed a structural field study focused on the analysis of fault-slip data. We measured 3920 faults in 132 sites. The data inversion (Angelier, 1990) allows us to reconstruct 267 paleostress states. In tilted sites, we were able to establish a relative age of the stress state with respect to folding. Syndepositional normal faults were found in Lower Jurassic, Campanian and Eocene units, indicating extensional tectonics during these time periods. In the light of these new data, we propose a new tectonic calendar for the southern Levant domain with five main steps.
(1) During Triassic, a NW-SE regional extension led to the develoment of the Levantine basin, as evidenced by offshore NE-SW basins and normal faults. In Lower Jurassic, NW-SE syndepositional normal faults indicate a NNE-SSW extension. Wether this extension reflects a major reorganization of the rifting process or a local deformation is not known.
(2) NNE-SSW extension occured during Campanian, as evidenced by NW-SE syndepositional normal faults and pre-tilting stress states affecting Upper Cretaceous units. This extension likely corresponds to a major regional event because the NW-SE trending Azrak and Euphrates grabens developped at the same time under similar conditions.
(3) Unconformities and thickness variations support a Santonian to Paleocene age for folding and inversion of previous structures. This folding is associated with a WNW-ESE compression. Active extension during Campanian indicates either that this folding phase was discontinuous since the Santonian (with the main folding phase during the Maastrichtian), or that it only started after the Campanian.
(5) During the Eocene, a N-S to NNE-SSW extension produced normal faulting in the whole NW Arabian platform as evidenced by syndepositional normal faults. This extension is known in Syria and Lebanon during Eocene-Oligocene.
(6) Since the Miocene, the northward movement of Arabia with respect to Africa led to the development of the 1000 km long left-lateral Dead Sea transform. It accommodated almost 100 km of displacement. It is associated with a strike-slip regime with a NNW-SSE compression, which is the main Neogene event. In the Galilee and Samaria, a WNW-ESE compression led folding and faulting during the Neogene, as evidenced the folded Miocene unconformity and compatible strike-slip faulting in Eocene rocks. Moreover, a newly described NE-SW compression occurred, maybe in relation with the beginning of the Zagros orogeny. In addition to these compressions, in the Galilee, the movement along the Levant transform also led the development of horsts, grabens and tilted blocks.

 

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