The structure, isostasy and gravity field of the Levant continental margin and the southeast Mediterranean area

Amit Segev, Michael Rybakov, Vladimir Lyakhovsky, Avraham Hofstetter, Gidon Tibor, Vladimir Goldshmidt, Zvi Ben Avraham

Research output: Contribution to journalArticlepeer-review


A 3-D layered structure of the Levant and the southeastern Mediterranean lithospheric plates was constructed using interpretations of seismic measurements and borehole data. Structural maps of three principal interfaces, elevation, top basement and the Moho, were constructed for the area studied. This area includes the African, Sinai and Arabian plates, the Herodotus and the Levant marine basins and the Nile sedimentary cone. In addition, an isopach map of the Pliocene sediments, as well as the contemporaneous amount of denuded rock units, was prepared to enable setting up the structural map of the base Pliocene sediment. Variable density distributions are suggested for the sedimentary succession in accord with its composition and compaction. The spatial density distribution in the crystalline crust was calculated by weighting the thicknesses of the lower mafic and the upper felsic crustal layers, with densities of 2.9 g/cm3 and 2.77 g/cm3, respectively. Results of the local (Airy) isostatic modeling with compensation on the Moho interface show significant deviations from the local isostasy and require variable density distribution in the upper mantle. Moving the compensation level to the base of the lithosphere (∼ 100 km depth) and adopting density variations in the mantle lithosphere yielded isostatic compensation (± 200 m) over most of the area studied. The spatial pattern obtained of a density distribution with a range of ± 0.05 g/cm3 is supported by a regional heat flux. Simulations of the flexure (Vening Meinesz) isostasy related to the Pliocene to Recent sedimentary loading and unloading revealed concentric oscillatory negative and positive anomalies mostly related to the Nile sedimentary cone. Such anomalies may explain the rapid subsidence in the Levant Basin and the arching in central Israel, northern Sinai and Egypt during Pliocene-Recent times. Comparison between the observed (Bouguer) gravity and the calculated gravity for the constructed 3-D lithospheric structure, which has variable density distributions, provided a good match and an independent constraint for the large-scale structure suggested and confirmed an oceanic nature for the Levant Basin lithosphere.

Original languageEnglish
Pages (from-to)137-157
Number of pages21
Issue number1-4
StatePublished - 13 Oct 2006
Externally publishedYes

Bibliographical note

Funding Information:
Discussions with R. Weinberger and Z. Gvirtzman were greatly appreciated. We thank Hans Thybo (editor), J. Ebbing and J.C. Mareschal for their constructive reviews, and B. Katz for editing the text. The study was partially supported by a grant from the US–Israel Binational Science Foundation (BSF), Jerusalem, Israel (2004946) to A. Segev and V. Lyakhovsky.


  • 3-D model
  • Gravity
  • Isostasy
  • Levant
  • Mediterranean
  • Middle East
  • Nile cone

ASJC Scopus subject areas

  • Geophysics
  • Earth-Surface Processes


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