Tectonic isolation of the
Levant basin offshore Galilee-Lebanon - Effects of the Dead Sea fault plate
boundary on the Levant continental margin, eastern Mediterranean
Schattner U.1, Ben-Avraham Z.1,
Lazar M.1 and C. Hüebscher2
1Department
of Geophysics and Planetary Sciences, Tel Aviv University, P.O.B. 39040, Ramat
Aviv, 69978, uris@gaia.tau.ac.il*,
zvi@terra.tau.ac.il,
2Institute
of Geophysics, University
of Hamburg, huebscher@dkrz.de.
The continental margin of the central
Levant, offshore northern Israel
and southern Lebanon
is characterized by a sharp continental-oceanic crustal transition, exhibited
on the bathymetry as a steep continental slope. At the base of the slope a
narrow zone of faulting deforms the upper Messinian-recent sedimentary sequence.
Further into the basin no major deformations are observed. However, onland a
restraining bend along the Dead Sea fault plate boundary results in the
formation of the Lebanon
and anti-Lebanon mountain ranges, which exhibit a large positive isostatic
anomaly not compensated at depth. All these geologic features follow a NNE-SSW
trend.
A dense network of multi-channel and
single-channel seismic profiles, covering 5000 km of
ship-track offshore northern Israel and southern Lebanon, was analyzed for the propose
of characterizing the continental margin. Additional seismic surveys covering
the area between the Levant margin and the
Cyprean Arc were examined. Data were then incorporated with magnetic, gravity
and earthquake measurements to reveal the deep crustal structure of the area
and integrated with bathymetry data to describe the behavior of the young
sedimentary basin fill.
Results indicate that the Levant basin,
offshore northern Israel and
southern Lebanon (up to Beirut) is more-or-less
unaffected by the intense tectonic deformation occurring onland. The transition
between the deformed area onland and the undeformed Levant Basin
occurs along the base of the continental slope. Along the base, the upper
Messinian-recent sedimentary sequence is cut by two sets of faults: shallow
growth faults resulting from salt tectonics and high angle faults, marking the
surface expression of a deeper crustal discontinuity - the marine extension of
the Carmel
fault zone.
The central Levant continental margin is being
reactivated by transpressional faulting of the marine continuation of the Carmel fault, at the base
of the continental slope. This fault system coincides with the sharp
continental-oceanic crustal transition, and acts as an isolator between the Levant Basin
and its land counterpart. To the north, this feature may initiate the formation
of a new triple junction, with the eastern Cyprean Arc (Latakia Ridge) and the
East Anatolian fault.