Аннотация
The gravity field of Dead Sea Rift / Dead Sea Transform was investigated
with regard to the isostatic state, the crustal density structure
of the orogeny and the rigidity of the lithosphere in the Central
Arava Valley. Our multi-national and interdisciplinary gravity group
with participants from the Geophysical Institute of Israel, the Natural
Resources Authority (Jordan), and the An-Najah National University
(Palestine), is aiming to study the crustal density structure, the
isostatic state of the lithosphere and mechanical properties of the
Dead Sea Rift system under the framework of the international DESERT
program which is coordinated by the GeoForschungsZentrum (GFZ, Potsdam,
Germany). The study area is located about 100 km away from both the
basin of the Dead Sea and the Gulf of Elat/Aqaba basin, respectively.
Between March and May 2002 some 800 new gravity observations were
recorded at a local(Arava valley) and regional scale (along the DESERT
seismic line). Station spacing in the Arava valley was 100 - 300
m and in the nearest neighborhood of the fault 50 m only. The survey
of detailed observations covered an area of 10 by 10 km and was completed
by a likewise dense survey at the western side of the valley in Israel.
All gravity data were tied to the IGSN -71 gravity datum and are
terrain-corrected as well. The station complete Bouguer gravity field,
Free air anomaly and residual isostatic anomalies (based on both
Airy and Vening-Meinesz models) were merged with the existing regional
gravity data bases of the region. Constraining information for the
3D density models at regional and local came from recent geophysical
field data acquisition and consist of seismic, seismological, electromagnetic,
and geologic studies which represent the integrated part of the interdisciplinary
research program. Novel methods e.g. curvature techniques, and Euler
deconvolution of the gravity fields shed new insight into the structure
of upper and lower crust and the causing density domains. In particular
the "dip-curvature" reveal a clear course of underground structures
which could be linked to the Arava fault system with their pull-apart
structures. The results of preliminary 3D density models which are
constrained by the seismic refraction and reflection profile of the
DESERT program and seismic tomography show a good correlation with
the near surface velocity field in the area of the Arava fault and
as lightly different picture of the Moho at a depth of interface
which stemmed from refraction modeling along the DESERT profile.
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