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A seismic refraction/wide-angle reflection experiment was undertaken in the Levant Basin, eastern Mediterranean. Two roughly east–west profiles extend from the continental shelf of Israel toward the Levant Basin. The northern profile crosses the Eratosthenes Seamount and the southern profile crosses several distinct magnetic anomalies. The marine operation used 16 ocean bottom seismometers deployed along the profiles with an air gun array and explosive charges as energy sources. The results of this study strongly suggest the existence of oceanic crust under portions of the Levant Basin and continental crust under the Eratosthenes Seamount. The seismic refraction data also indicate a large sedimentary sequence, 10–14 km thick, in the Levant Basin and below the Levant continental margin. Assuming the crust is of Cretaceous age, this gives a fairly high sedimentation rate. The sequence can be divided into several units. A prominent unit is the 4.2 km/s layer, which is probably composed of the Messinian evaporites. Overlying the evaporitic layer are layers composed of Plio–Pleistocene sediments, whose velocity is 2.0 km/s. The refraction profiles and gravity and magnetic models indicate that a transition from a two layer continental to a single-layer oceanic crust takes place along the Levant margin. The transition in the structure along the southern profile is located beyond the continental margin and it is quite gradual. The northern profile, north of the Carmel structure, presents a different structure. The continental crust is much thinner there and the transition in the crustal structure is more rapid. The crustal thinning begins under western Galilee and terminates at the continental slope. The results of the present study indicate that the Levant Basin is composed of distinct crustal units and that the Levant continental margin is divided into at least two provinces of different crustal structure. 相似文献
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Geophysical prediction and following development sinkholes in two Dead Sea areas, Israel and Jordan 总被引：2，自引：0，他引：2
M. G. Ezersky L. V. Eppelbaum A. Al-Zoubi S. Keydar A. Abueladas E. Akkawi B. Medvedev 《Environmental Earth Sciences》2013,70(4):1463-1478
Geophysical methods—seismic refraction (SRFR), electrical resistivity tomography (ERT), and microgravity—were applied to the Dead Sea (DS) sinkhole problem in the Ein Gedi area at the earlier stage of the sinkhole development (1998–2002). They allowed determining the sinkhole formation mechanism and localizing the sinkhole hazardous zones. The SRFR method permitted to delineate the underground edge of a salt layer at the depth of 50 m. The salt edge was shaped like the sinkhole line on the surface. It was concluded that the sinkhole development is linked to the salt edge. Geoelectrical quasi-3D mapping based on the ERT technique detected large resistivity anomalies with 250–300 m2 diameter and 25–35 m deep. The Ein Gedi area has been also mapped by the use of Microgravity method. The residual Bouguer gravity anomaly map shows negative anomalies arranged along the edge of the salt layer. Those gravity anomalies overall are very similar in plan to the resistivity distribution in this area. The results of forward modeling indicate that both high resistivity and residual gravity anomalies are associated with a subsurface decompaction of the soil mass and deep cavity at the sinkhole site. Following monitoring of the sinkhole development carried out by the Geological Survey of Israel confirmed our suggestions. The drilling of numerous boreholes verified the location of the salt edge. Geographical Information System (GIS) database testifies that during 2003–2009 new sinkholes are continuing to develop along the salt edge within a narrow 50–100 m wide strip oriented approximately in north–south direction (slightly parallel to the shoreline). No promotion in west–east direction (perpendicularly to the DS shoreline) was observed in Israel. Collapse of sinkholes and their clustering have been occurred within the area of high resistivity anomaly and negative residual gravity anomaly. Similar studies carried out at the Ghor Al-Haditha area (Jordan) have shown that sinkholes there are also arranged along the winding line conforming to the salt edge. In this area sinkholes are slowly moved to the Dead Sea direction. Results of geophysical studies in numerous DS sites indicate similar sinkhole development. It allowed generating of the sinkhole formation model based on ancient (10,000–11,000-year old) salt belt girding the Dead Sea along its shores 相似文献
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As a consequence of drilling and completion operations most wells have reduced permeability near the borehole (skin zone). This may result in a corresponding change of thermal conductivity of formations near the borehole. At the same time the mathematical models, which describe the process of thermal recovery of formations are based on the assumption that the thickness of the radius of heated zone (during circulation of the drilling mud) is significantly larger than the well radius (or skin zone). It is shown below that the radius of the heated zone (radius of investigation or radius of thermal influence) can be approximated by simple formulas. It is shown that for six field bottom-hole temperature surveys the radius of thermal influence (RTI) is too small, and for this reason, the duration of the drilling mud circulation period should increased. 相似文献
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The determination of the lower edges of magnetized bodies in the Earth's crust is a complex geophysical problem, although these values can be estimated by using geothermal data. An analysis of the temperature regime and location of the lower edges of magnetized bodies has been carried out for the geosynclinal region of the southern Caucasus and the area joining the ancient platform with the Arabian Shield in Israel. Geothermal calculations for Israel have been performed for three models of the thermal regime for the Earth's crust and upper mantle. The process of ultrabasic rock serpentinization is accompanied by the transformation of iron suboxide to iron oxide. Both these processes run under identical thermodynamic conditions within an average temperature interval of 200°-400°C. The Curie surface controls the position of lower edges only in fault zones where oxidation conditions hold up to great depths. 相似文献
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Thermodynamic conditions (first of all, temperature) are the main dynamic factors in the transformation process of ferrous
to ferric iron (TFFI). TFFI usually takes place within a temperature range of 473–843 K (most active at temperatures above
673 K) and does not require presence of the oxidizing agents above 673 K. Analysis of the chemical composition of different
rocks and minerals indicates that only for some sedimentary rocks is the relative content of ferrous iron oxide less than
its value in magnetite, and this value is minimal for oceanic sediments. The relative content of ferrous iron oxide in oceanic
magmatic rocks exceeds this value in continental magmatic rocks and depends on the rate of rock cooling. An investigation
of the role of the titanium oxide content of different rocks on stability of ferrous iron oxide against its transformation
to ferric iron oxide shows that a significant correlation (r = 0.79) does exist between the relative content of ferrous iron oxide and ratio of TiO2/Fe2O3. Temperature within the solar nebula at location of the Earth was within the temperature range of the TFFI. During the Earth
accretion and its early evolution, ferric iron oxide was unstable and most likely did not exist. The first magnetic minerals
containing ferric iron could have appeared only after the Earth’s surface had cooled below ∼843 K. The formation of the first
Algoma-type banded iron formations could be used as a marker of the Earth’s surface cooling below ∼843 K. 相似文献
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A. V. Nikolaev D. S. Gorkin L. V. Eppelbaum N. Arnon P. G. Manukov A. Libin A. M. Buloshnikov 《Doklady Earth Sciences》2018,482(2):1320-1323
The archeological site of Machpelah Temple (Cave of the Patriarchs), Israel, was studied. At the moment, the first stage of investigations is finished: it included the study of a certain part inside the temple proper. New high-frequency impulse sounding hardware was applied, and its depth and spatial resolution of physical inhomogeneities exceeded the capabilities of existing electromagnetic prospecting methods by an order of magnitude. 相似文献