Dead Sea Transform Fault System Research Articles

Retracted Article: A Spiritual View to the Huge Earthquake in Türkiye

The shaking of the earth is a common phenomenon that has been experienced by humans from the earliest of times.[1] The Dead Sea Transform fault system, also sometimes referred to as the Dead Sea Rift, is a series of faults that run from the Maras Triple Junction (a junction with the East Anatolian Fault in southeastern Türkiye) to the Northern end of the Red Sea Rift (just offshore of the Southern tip of the Sinai Peninsula).[2] Throughout history, many large earthquakes have occurred in the Dead Sea Transform fault system. In the 1800s before Christ, the earthquake, which is stated in the Quran[3] [4] as punishment for the people of Lut (Lot)[5] for their denial and immorality, probably took place in the Dead Sea Rift region.[6] Maghreb (Northwest African region), Egypt, Antakya (Antioch), Damascus (Dimaşk), Mosul, Homs (Hims), and whole Al-Jazira region were affected by the earthquake that occurred on November 24, 847 with an estimated magnitude of 7.0. In that earthquake, 20,000 people in Antakya and 50,000 people in Mosul died.[6] Lastly, on February 6, 2023 at 04:17 a.m. Türkiye time, a massive earthquake struck Southern Türkiye and Syria with a magnitude of Mw 7.7. An unusually strong Mw 7.6 aftershock as well as hundreds of smaller aftershocks occurred at 01:24 p.m. Türkiye time after the mainshock. Very heavy damage and tens of thousands of deaths occurred. Herein, we discussed earthquake from the Islamic perspective to attract attention to the spiritual dimension of the earthquake.

Expanding the speciation of terrestrial molybdenum: Discovery of polekhovskyite, MoNiP2, and insights into the sources of Mo-phosphides in the Dead Sea Transform area

Abstract Polekhovskyite, MoNiP2, is the first terrestrial Mo phosphide, a phosphorus-rich homolog of meteoritic monipite, MoNiP. The mineral represents a novel phosphide type of terrestrial Mo speciation. It was discovered among phosphide assemblages in pyrometamorphic rocks of the Hatrurim Formation (the Mottled Zone) in Israel, the area confined to the Dead Sea Transform fault system. Polekhovskyite occurs in the altered diopside microbreccia, as micrometer-sized euhedral crystals intimately intergrown with murashkoite, FeP and transjordanite, Ni2P, in association with Si-rich fluorapatite, hematite, and magnetite. In reflected light, the mineral has a bluish-gray color with no observable bireflectance and anisotropy. Chemical composition (electron microprobe, wt%): Mo 44.10, Ni 22.73, Fe 4.60, P 29.02, total 100.45, which corresponds to the empirical formula Mo0.99(Ni0.83Fe0.18)1.01P2.01 and leads to the calculated density of 6.626 g/cm. Polekhovskyite is hexagonal, space group P63/mmc, a = 3.330(1), c = 11.227(4) Å, V = 107.82(8) Å3, and Z = 2. The crystal structure has been solved and refined to R1 = 0.0431 based on 50 unique observed reflections. The occurrence of Mo-bearing phosphides at the Dead Sea Transform area is a regional-scale phenomenon, with the localities tracked across both Israel and Jordan sides of the Dead Sea. The possible sources of Mo required for the formation of Mo-bearing phosphides are herein reviewed; they are likely related to the processes of formation of the Dead Sea Transform fault system. The problem of anthropogenic contamination of geological samples with Mo and Ni is also discussed in the paper in the context of the general aspects of discrimination between natural and technogenic ultra-reduced phases.

Asymmetry of faults and stress patterns within the Dead Sea basin as displayed by seismological analysis

The Dead Sea pull-apart basin (DSB), which is located within the Dead Sea Transform fault system, displays tectonic asymmetry between its eastern and western longitudinal zones. We investigate the seismological and mechanical signature of this asymmetry by the analyzing the hypocenter distribution and focal-mechanisms of 114 Mw = 1.5–5.2 earthquakes recorded from 1985 till 2012. The analysis indicates that the seismicity along the western longitudinal zone is deeper than the eastern one. Focal mechanism analysis indicates that about 50% of solutions are strike-slip, compatible with the plate motions along the Dead Sea transform. Comparison between the two longitudinal zones of the basin shows that the focal mechanisms in the eastern DSB are dominated by strike-slip faulting shallower than 12 km depth, whereas those in the western DSB are dominated by oblique faulting below 12 km depth. The b value of the Gutenberg-Richter magnitude distributions also show difference between the two zones with ~0.9 in the west and ~0.7 in the east zone.We develop stress-inversion analysis to identify the fault planes of the focal mechanisms by using friction-dependent selection process. The horizontal maximum compression (σHmax) trends NNW-SSE, with increasing value of the vertical stress component along the western part of the basin, corresponds to the oblique faulting in this zone. The optimal friction coefficient determined by the stress-inversion for the fault planes is μ ~ 0.5. Our analysis emphasizes the significant contribution of frictional dependent stress-inversion as an effective tool in seismotectonic analysis.

Interseismic deformation in the Gulf of Aqaba from GPS measurements

SUMMARYAlthough the Dead Sea Transform (DST) fault system has been extensively studied in the past, little has been known about the present-day kinematics of its southernmost portion that is offshore in the Gulf of Aqaba. Here, we present a new GPS velocity field based on three surveys conducted between 2015 and 2019 at 30 campaign sites, complemented by 11 permanent stations operating near the gulf coast. Interseismic models of strain accumulation indicate a slip rate of $4.9^{+0.9}_{-0.6}~\mathrm{ mm}\,\mathrm{ yr}^{-1}$ and a locking depth of $6.8^{+3.5}_{-3.1}~\mathrm{ km}$ in the gulf’s northern region. Our results further indicate an apparent reduction of the locking depth from the inland portion of the DST towards its southern junction with the Red Sea rift. Our modelling results reveal a small systematic left-lateral residual motion that we postulate is caused by, at least in part, late post-seismic transient motion from the 1995 MW 7.2 Nuweiba earthquake. Estimates of the moment accumulation rate on the main faults in the gulf, other than the one that ruptured in 1995, suggest that they might be near the end of their current interseismic period, implying elevated seismic hazard in the gulf area.

Seismic and Geodetic Crustal Moment-Rates Comparison: New Insights on the Seismic Hazard of Egypt

A comparative analysis of geodetic versus seismic moment-rate estimations makes it possible to distinguish between seismic and aseismic deformation, define the style of deformation, and also to reveal potential seismic gaps. This analysis has been performed for Egypt where the present-day tectonics and seismicity result from the long-lasting interaction between the Nubian, Eurasian, and Arabian plates. The data used comprises all available geological and tectonic information, an updated Poissonian earthquake catalog (2200 B.C.–2020 A.D.) including historical and instrumental datasets, a focal-mechanism solutions catalog (1951–2019), and crustal geodetic strains from Global Navigation Satellite System (GNSS) data. The studied region was divided into ten (EG-01 to EG-10) crustal seismic sources based mainly on seismicity, focal mechanisms, and geodetic strain characteristics. The delimited seismic sources cover the Gulf of Aqaba–Dead Sea Transform Fault system, the Gulf of Suez–Red Sea Rift, besides some potential seismic active regions along the Nile River and its delta. For each seismic source, the estimation of seismic and geodetic moment-rates has been performed. Although the obtained results cannot be considered to be definitive, among the delimited sources, four of them (EG-05, EG-06, EG-08, and EG-10) are characterized by low seismic-geodetic moment-rate ratios (<20%), reflecting a prevailing aseismic behavior. Intermediate moment-rate ratios (from 20% to 60%) have been obtained in four additional zones (EG-01, EG-04, EG-07, and EG-09), evidencing how the seismicity accounts for a minor to a moderate fraction of the total deformational budget. In the other two sources (EG-02 and EG-03), high seismic-geodetic moment-rates ratios (>60%) have been observed, reflecting a fully seismic deformation.

Multi- and inter-disciplinary approaches towards understanding the sinkholes’ phenomenon in the Dead Sea Basin

Over the last few decades, thousands of sinkholes have developed at an increasing pace, with the majority along the western and eastern shores of the Dead Sea. Recent studies indicate that the number of sinkholes in the Dead Sea Basin (DSB) has reached more than 6000; each of them, on average, 1–10 m deep and up to 25–30 m in diameter. These sinkholes can open-up suddenly and swallow whatever exists above them, resulting in an area that looks like an earthquake zone. Sinkholes in the DSB are formed when a subterranean salt layer that once bordered the Dead Sea is dissolved by underground freshwater that follows the migration of the saltwater–freshwater interface, due to receding water level of the Dead Sea. Consequently, large areas of land are subsiding, causing the formation of sinkholes in the region. Also, based on the fact that the Dead Sea’s region is tectonically and seismically active, as being greatly affected by the Dead Sea transform fault system, sinkholes can also be evolved as a result of tectonic and seismic activities. This paper presents multi- and inter-disciplinary approaches towards understanding the occurrence of sinkholes in the DSB, with respect to geomorphology, geology, geophysics, tectonics, seismology, limnology, climatology, biodiversity, and socioeconomics, as well as the steady decline of the Dead Sea’s water level and the continuous shrinkage of its surface area and its water volume, at alarming rates. The occurrence of sinkholes in this region could be attributed to anthropogenic reasons and/or natural reasons.

Geochemical characterisation of gases along the dead sea rift: Evidences of mantle-co2 degassing

The Dead Sea Transform (DST) fault system, where a lateral displacement between the African and Arabian plates occurs, is characterised by anomalous heat flux in the Israeli area close to the border with Syria and Jordan. The concentration of He and CO2, and isotopic composition of He and total dissolved inorganic carbon were studied in cold and thermal waters collected along the DST, in order to investigate the source of volatiles and their relationship with the tectonic framework of the DST. The waters with higher temperature (up to 57.2°C) are characterised by higher amounts of CO2 and helium (up to 55.72 and 1.91∗10−2 cc l−1, respectively). Helium isotopic data (R/Ra from 0.11 to 2.14) and 4He/20Ne ratios (0.41–106.86) show the presence of deep-deriving fluids consisting of a variable mixture of mantle and crust end-members, with the former reaching up to 35%. Carbon isotope signature of total dissolved carbon from hot waters falls within the range of magmatic values, suggesting the delivery of deep-seated CO2. The geographical distribution of helium isotopic data and isotopic carbon (CO2) values coupled with (CO2/3He ratios) indicate a larger contribution of mantle-derived fluids affecting the northern part of the investigated area, where the waters reach the highest temperature. These evidences suggest the occurrence of a favourable tectonic framework, including a Moho discontinuity up-rise and/or the presence of a deep fault system coupled with the recent magmatic activity recognised in the northern part of Israel.

Helium isotopes in Dead Sea Transform waters

The concentrations and isotopic compositions of helium, and relative abundances of CO2, were studied in brines and freshwater springs, groundwater wells, and gas bubbles, in and around the Dead Sea Transform (DST) fault system. The latter forms part of the plate boundary between the African and Arabian plates along which intensive tectonic and volcanic activity occurred and where a range of freshwater to hypersaline water bodies percolate.The atmosphere-normalized 3He/4He ratios (R/Ra) show a distinct geographic gradient, whereby fluids in the north part of the DST, near Lake Kinneret, are characterized by R/Ra≈2. These values decrease gradually southward until the Arava Valley, where they are approximately 0.15, reflecting a corresponding decrease in the mantle-derived He fraction, from about ~30% in the north, to a few percent in the south. Freshwater springs outside the DST, in the Galilee and Judea Mountains, are characterized by R/Ra ratios close to unity, reflecting the dominance of atmosphere-derived helium, although they still contain a few percent of a mantle component.The spatial pattern of change in R/Ra ratios is independent of regional tectonic activity (rifting), which is similar around the Lake Kinneret basin and the Dead Sea, and a correlation does not exist between such activity and He concentrations and CO2/3He ratios. In contrast, helium concentrations, and to a lesser extent CO2/He ratios, correlate with temperatures of the sampled fluids, reflecting a dilution process of a deep, hot mantle component as it percolates upwards toward the surface. The preferential injection of a mantle He toward the surface in the north DST is facilitated by deep faults and a shallower Moho boundary, which are also associated with enhanced volcanism in the north DST, and is superimposed over a regionally scaled mantle background value. Regionally, the observations reflect a transition from a domination of a dilute mantle end member in the north, which itself is the product of a mixture between mantle and crustal helium, to a dominant crustal (radiogenic) end member in the south.The R/Ra ratio in basaltic olivines and diopside from the Golan is on average 6.6±0.7, lower than typical mantle values (~8) but corresponding to comparable sub-continental mantle compositions.

A shear wave velocity model of the European upper mantle from automated inversion of seismic shear and surface waveforms

SUMMARY We present a new, S-velocity model of the European upper mantle, constrained by inversions of seismic waveforms from broad-band stations in Europe and surrounding regions. We collected seismograms for the years 1990–2007 from all permanent stations in Europe for which data were available. In addition, we incorporated data from temporary experiments. Automated multimode inversion of surface and S-wave forms was applied to extract structural information from the seismograms, in the form of linear equations with uncorrelated uncertainties. The equations were then solved for seismic velocity perturbations in the crust and mantle with respect to a 3-D reference model with a realistic crust. We present two versions of the model: one for the entire European upper mantle and another, with the highest resolution, focused on the upper 200 km of the mantle beneath western and central Europe and the circum Mediterranean. The mantle lithosphere and asthenosphere are well resolved by both models. Major features of the lithosphere–asthenosphere system in Europe and the Mediterranean are indentified. The highest velocities in the mantle lithosphere of the East European Craton (EEC) are found at about 150 km depth. There are no indications for a deep cratonic root below about 330 km depth. Lateral variations within the cratonic mantle lithosphere are resolved as well. The locations of kimberlites correlate with reduced S-wave velocities in the shallow cratonic mantle lithosphere. This anomaly is present in regions of both Proterozoic and Archean crust, pointing to an alteration of the mantle lithosphere after the formation of the craton. Strong lateral changes in S-wave velocity are found at the northwestern margin of the EEC and may indicate erosion of cratonic mantle lithosphere beneath the Scandes by hot asthenosphere. The mantle lithosphere beneath western Europe and between the Tornquist–Teisseyre Zone and the Elbe Line shows moderately high velocities and is of an intermediate character, between cratonic lithosphere and the thin lithosphere of central Europe. In central Europe, Caledonian and Variscian sutures are not associated with strong lateral changes in the lithosphere–asthenosphere system. Cenozoic anorogenic intraplate volcanism in central Europe and the circum Mediterranean is found in regions of shallow asthenosphere and close to changes in the depth of the lithosphere–asthenosphere boundary. Very low velocities at shallow upper-mantle depths are present from eastern Turkey towards the Dead Sea transform fault system and Sinai, beneath locations of recent volcanism. Low-velocity anomalies extending vertically from shallow upper mantle down to the transition zone are found beneath the Massif Central, Sinai and the Dead Sea, the Canary Islands and Iceland.

Hypogene and supergene alteration of the zeolite-bearing pyroclastic deposits at Tell Rimah, Jordan, and rift-related processes along the Dead-Sea-Transform Fault System during the Quaternary

The boundary between the Arabian and African plates, is marked in the Middle East by one of the most prominent deep-seated lineamentary structures, called the Dead-Sea-Transform Fault System (DSTFS). Structural and mineralogical processes related to the DSTFS were correlated with equivalent processes leading to the alteration of pyroclastic deposits of alkali-olivine basaltic to nepheline basaltic composition which formed during a time span of less than 0.5Ma. The large deposit of Tell Rimah, Jordan, is operated for the exploitation of zeolites, tuffs, and as pozzolana raw material. Four discrete stages of mineralizations have been distinguished from each other within these volcanic-hosted mineral deposits.(1) Hypogene syneruptive alteration of pyroclastic rocks produced siliceous gels (“allophane”), smectite, analcime, and phillipsite in vesicles when the groundwater level was low in the rift basin of the DSTFS. The lake-level lowstand caused the fluid system in the pyroclastic cone to become self-sufficient and it has been considered as a closed hydrothermal system. (2) Periods of tectonic and magmatic quiescence grinded the detrital sedimentation in the rift basin to a halt, while triggering a supergene alteration in the eruptive cones on the adjacent Arabian Plate. (3) Epigenetic alteration affected the pyroclastic rocks in the distal part of the DSTFS as a result of a rising water level. The water gradually filled the pore space of the permeable pyroclastic deposits almost to completeness and caused meniscus and blocky cements of calcite, phillipsite and chabazite to develop. In the rift basin, contemporaneously with the alteration of the pyroclastic rocks, freshwater limestones formed on calcareous bedrocks. Ba and Mn minerals in these freshwater limestones were supplied by subaquatic brines. Subsequently, a drastic lowering of the lake water level in the DSTFS converted the system of subaquatic freshwater limestones into subaerial tufa and travertine. As long as the basal parts of the pyroclastic units at Tell Rimah were in the reaches of the saline groundwaters, calcite and faujasite developed in the pyroclastic host rocks. (4) Another lake level lowstand within the rift basin caused the pyroclastic host rocks to get emerged and forced zeolite–carbonate mineralization in the tuffs to a complete stillstand. Hypogene and supergene alteration in these phreatomagmatic–strombolian pyroclastic cones of the Pleistocene x were correlated with lake high- and lowstands in the adjacent rift basin along the DSTFS.The results obtained by current tectono-morphological studies of the rift-related alteration of pyroclastic rocks along the DSTFS may also be applied to basin-and-swell-topographies elsewhere in the world. The current studies involved microscopy supplemented by SEM-EDX, X-ray diffraction analysis, mid (MIR) and far (FIR) infrared spectroscopy. Major and trace elements were analyzed by X-ray fluorescence spectrometry (XRF). C- and O isotope analyses were conducted on carbonate minerals, which were also targeted on by radiocarbon dating.

Anatomy of landslides along the Dead Sea Transform Fault System in NW Jordan

In the mountainous region north of Amman, Jordan, Cenomanian calcareous rocks are being monitored constantly for their mass wasting processes which occasionally cause severe damage to the Amman–Irbid Highway. Satellite remote sensing data (Landsat TM, ASTER, and SRTM) and ground measurements are applied to investigate the anatomy of landslides along the Dead Sea Transform Fault System (DSTFS), a prominent strike-slip fault. The joints and faults pertinent to the DSTFS match the architectural elements identified in landslides of different size. This similarity attests to a close genetic relation between the tectonic setting of one of the most prominent fault zones on the earth and modern geomorphologic processes. Six indicators stand out in particular:1) The fractures developing in N–S and splay faults represent the N–S lateral movement of the DSTFS. They governed the position of the landslides. 2) Cracks and faults aligned in NE–SW to NNW–SSW were caused by compressional strength. They were subsequently reactivated during extensional processes and used in some cases as slip planes during mass wasting. 3) Minor landslides with NE–SW straight scarps were derived from compressional features which were turned into slip planes during the incipient stages of mass wasting. They occur mainly along the slopes in small wadis or where a wide wadi narrows upstream. 4) Major landslides with curved instead of straight scarps and rotational slides are representative of a more advanced level of mass wasting. These areas have to be marked in the maps and during land management projects as high-risk area mainly and may be encountered in large wadis with steep slopes or longitudinal slopes undercut by road construction works. 5) The spatial relation between minor faults and slope angle is crucial as to the vulnerability of the areas in terms of mass wasting. 6) Springs lined up along faults cause serious problems to engineering geology in that they step up the behavior of marly interbeds to accelerate sliding during mass wasting. The most vulnerable areas prone to slope instabilities are those with compressional tectonics followed by extensional movements, with fault bound springs and smectite-bearing marly layers interbedded with pure massive limestones. The semi-arid to arid climate with periodic rainfalls combined with subsurface water circulation along the joints and faults can trigger mass wasting.

The surface heat flow of the Arabian Shield in Jordan

Surface heat flow in southern Jordan (western part of the Arabian Plate) was determined in a dense cluster of five, up to 900-m-deep boreholes that have encountered sedimentary rocks of Paleozoic (Ordovician and Silurian) age. These rocks are underlain by an igneous and metamorphic basement, which has been studied for its radiogenic heat production, along the eastern margin of the Dead Sea Transform (DST) fault system. The heat flow, calculated from continuous temperature logs and laboratory-measured thermal conductivity of drillcores and surface samples, averages to 60.3 ± 3.4 mW m −2 and contrasts the common view of the late Proterozoic-consolidated Arabian Shield constituting a low heat-flow province of ⩽45 mW m −2. Although only characterizing an area of about 300 km 2, this average is unlikely representing a positive local anomaly caused by voluminous HHP granites/rhyolites at shallow depths. Instead, a heat flow of 60 mW m −2 is considered a robust estimate of the Phanerozoic conductive surface heat flow not only for Jordan, but for the Arabian Shield in areas unaffected by younger reactivation. The large variation in conductive heat flow (36–88 mW m −2) previously observed in Jordan, southern Syria, and Saudi Arabia is irreconcilable with their broad similarity in lithosphere structure and composition and rather reflects a combination of factors including low-quality temperature data and insufficient knowledge on thermal rock properties.

Evidence for ground-rupturing earthquakes on the Northern Wadi Araba fault at the archaeological site of Qasr Tilah, Dead Sea Transform fault system, Jordan

The archaeological site of Qasr Tilah, in the Wadi Araba, Jordan is located on the northern Wadi Araba fault segment of the Dead Sea Transform. The site contains a Roman-period fort, a late Byzantine–Early Umayyad birkeh (water reservoir) and aqueduct, and agricultural fields. The birkeh and aqueduct are left-laterally offset by coseismic slip across the northern Wadi Araba fault. Using paleoseismic and archaeological evidence collected from a trench excavated across the fault zone, we identified evidence for four ground-rupturing earthquakes. Radiocarbon dating from key stratigraphic horizons and relative dating using potsherds constrains the dates of the four earthquakes from the sixth to the nineteenth centuries. Individual earthquakes were dated to the seventh, ninth and eleventh centuries. The fault strand that slipped during the most recent event (MRE) extends to just below the modern ground surface and juxtaposes alluvial-fan sediments that lack in datable material with the modern ground surface, thus preventing us from dating the MRE except to constrain the event to post-eleventh century. These data suggest that the historical earthquakes of 634 or 659/660, 873, 1068, and 1546 probably ruptured this fault segment.

Neogene volcanic activity of western Syria and its relationship with Arabian plate kinematics

The Cenozoic (mostly Neogene) volcanic activity in Syria is part of the extensive magmatism that took place in the Mashrek Region, Middle East, from upper Eocene to Holocene (∼40–0.0005 Ma). Samples in western Syria are mostly high TiO2 (TiO2 ∼1.8–3.7 wt.%) alkaline mafic rocks (basanites, hawaiites and alkali basalts) plus rare transitional/tholeiitic basalts and basaltic andesites) with within-plate-like trace element signature. On the basis of incompatible trace element content, the volcanic activity in Syria has been divided into two stages: the first lasting from ∼25 to ∼5 Ma and the second from ∼5 to recent times. Indeed, the Syrian lavas show incompatible trace element content increasing with decreasing age from ∼25 to ∼5 Ma, followed by an abrupt decrease to low values roughly at the Miocene–Pliocene boundary. This temporal shift in composition is related to major tectonic re-organization occurred during upper Miocene. The proposed petrogenetic model invokes three steps: (a) passive upwelling of the shallow asthenosphere during the development of the Dead Sea transform fault system. Different degrees of partial melting were followed by variable extents of fractional crystallization and limited upper crustal contamination; (b) the Miocene–Pliocene boundary tectonic change enhanced passive decompression of the same sources and a consequent increase in degree of partial melting resulting in low incompatible trace element content of the relatively high-volume liquids; (c) after this phase, the incompatible trace element content in the basaltic magmas increased as consequence of fractional crystallization processes. Major and trace element content similarities with the rest of the circum-Mediterranean igneous rocks are consistent with a common relatively shallow origin for the Cenozoic anorogenic magmatism of the entire circum-Mediterranean area (the so-called Common Magmatic Reservoir). Because much of the igneous activity in the studied area is concentrated near the Dead Sea fault, the origin of Cenozoic magmatism in Syria (and in the rest of the circum-Mediterranean area) reflects a strong lithospheric control on the loci of partial melting. Mantle plumes from lower mantle and/or north-westward channelling of the Afar mantle plume is not needed to explain volcanic activity in Syria and the Mashrek area.

Cenozoic volcanism in the Middle East: petrogenesis of alkali basalts from northern Lebanon

The Cenozoic volcanic field of the Akkar region in northern Lebanon consists of a thick succession (200 m) of basaltic lava flows, erupted at the junction between a restraining bend (the Yammouneh transform fault) and its northern extension (the Ghab transform) in Syria. Both faults are part of the Dead Sea transform fault system, which represents the boundary between the Arabian and African plates and the Levantine subplate. The lavas are made up of about 15–25 vol. % olivine (Fo79–84), 30–40 % clinopyroxene (salite), 40–50 % plagioclase (An58–67), and opaque Fe–Ti oxides (∼ 5 %). Geochemically, they exhibit a narrow range of SiO2 (44.6 to 47.0 wt %), and MgO (2.9 to 7.5 wt %), are relatively enriched in TiO2 (2.0 to 2.9 wt %), and are classified as alkali basalts. Mg-numbers range from 0.32 to 0.59, with an average of 0.47. The rocks are enriched in incompatible trace elements such as Zr (98–184 ppm), Nb (16–39 ppm) and Y (25–34 ppm). The REE patterns are fractionated ((La/Yb)N=8.2), and are generally parallel to subparallel. Such compositions are typical of those of HIMU-OIB and plume-related magmas. Elemental ratios such as K/P (2.9), La/Ta (21.8), La/Nb (0.80), Nb/Y (0.92) and Th/Nb (0.35), and the low average SiO2 content (46.1 wt %) suggest that the magma was subjected to minimal crustal contamination. This may be related to a rapid ascent of the parental magma, in agreement with the nature (mafic, oceanic crust-like) and the thickness (only about 12 km) of the crust of the Eastern Mediterranean region. Cenozoic volcanism in this region is interpreted to have occurred in association with an episode of localized extension, particularly at the junction between the Yammouneh restraining bend and the Dead Sea–Ghab Transform (that is, in a transtensional tectonic regime). The 143Nd/144Nd isotopic composition of the basaltic rocks of northern Lebanon ranges from 0.512842 to 0.512934 (εNd=4.0 to 5.8), and 87Sr/86Sr from 0.703317 to 0.703579, suggesting a HIMU-like mantle source. Modelling indicates that the magma was produced by a small degree of partial melting (F=2 %) of a primitive, garnet lherzolitic mantle source, possibly containing a minor spinel component.

Evaluation of geodynamic activity of the Dead Sea transform fault by radon gas concentrations

Twelve radon lines of dosimeters (detectors) were placed across the Jordan Valley active fault, which is a segment of the active Dead Sea transform fault system. Each line of the dosimeters shows one or more peaks of radon anomaly concentrations. Some of these peaks prove the intersection of the fault trace with these lines in areas where the fault plane is inferred. In other lines, the peaks correspond to the arrangement of faults in areas of pull-apart basins (sag ponds) or pressure ridges, formed due to the left or right step of the fault. Sag ponds usually show low radon emanations, because they are the place for the accumulation of very fine sediments, which decreases their porosity and hence the upward migration of the radon gas. The northern part of the Jordan Valley relatively shows high radon emanation, which could be attributed to the presence of a seismic gap in the upper Jordan valley.

The 1138–1139 and 1156–1159 destructive seismic crises in Syria, south-eastern Turkey and northern Lebanon

The aim of this study is to shed light ontwo important destructive seismicsequences, about 20 years apart (1138–1139and 1156–1159), which hit the northernsector of the Dead Sea transform faultsystem (DSTFS), in the easternMediterranean region. Although some ofthese earthquakes were already known to thescholarly tradition, the interpretationsprovided until today have largely beenpartial and characterised by uncertaintiesand discrepancies among the variousauthors. Our study has developed throughresearch into the original Arabic, Syriac,Armenian and Latin texts and a criticalanalysis relating to a territory fragmentedby the presence of the Christian-Latinstates. This analysis has allowed us toshed light on the already existing, albeitoften uncertain, information and to add newelements of these two important series ofearthquake shocks to our knowledge base.As regards the first seismic sequence(October 1138–June 1139), apart from havingdefined the date with greater accuracy,eight new locations affected have beenidentified, unknown to previous studies.The shocks jolted a vast area withdestructive effects, including theterritory of Aleppo (modern Halab, Syria)and the western part of the region ofEdessa (modern Urfa, Turkey).The second seismic sequence (September1156–May 1159) was much longer anddevastating, and hit a huge area, includedbetween the present-day territories ofnorth-western Syria, northern Lebanon andthe region of Antioch (modern Antakya, insouthern Turkey). A detailed analysis ofthe primary sources has allowed toreconstruct the series of shocks withchronological detail of the effects,improving our previous knowledge. Lastly,the authors formulate an hypothesis as tothe possible seismogenic zones affected.

What is the reason for the Dead Sea Transform fault system segmentation?

What is the reason for the Dead Sea Transform fault system segmentation?

Seismic reflection profiles across the southern Dead Sea basin

The main structural and stratigraphic elements that form the Southern Dead Sea basin (SDSB), which is part of the Dead Sea transform fault system, have been broadly delineated with various degrees of certainty by a number of researchers. The recent exchange of seismic data between Israel and Jordan enable us to fill in some of the dashed lines and eliminate some of the question marks that appear on the previously published geological cross-sections. Two east–west seismic time sections, one from each side of the international border that dissect the basin, have been selected, composed and interpreted. A remarkable correlation of the three major sedimentary sequences that form the basin-fill (Miocene clastics, Pliocene salt and Pleistocene–Holocene clastics and evaporites) has been established between the lines and, hence, across the entire width of the SDSB. The Miocene and Pliocene series are cut off in the east by the Ghor–Safi fault that is the equivalent of the western Sedom fault, thus, indicating that all three major structural steps, known to exist in the west: (1) rim block, (2) intermediate block and (3) deep block, occurs also in the east, and that the SDSB is indeed a full graben. The Ghor Safi fault is the northern extension of the major Arava strike-slip fault. The very thin Miocene (if at all) and lack of Pliocene salt in the eastern intermediate block, unlike the western one, suggests that the Ghor–Safi fault was initiated earlier then the Sedom fault. Salt is present over the entire width of the basin but does not exceed the 900 m that were penetrated by the Sedom Deep-1 borehole. The salt is conformable with the overlying thick Pleistocene and except for the Sedom diapir, no halokinesis phenomena have been recognized to be associated with both units.

Structure and tectonic development of the Ghab basin and the Dead Sea fault system, Syria

We examine the structure and evolution of the Ghab basin that formed on the active, yet poorly understood, northern segment of the Dead Sea transform fault system. The basin formed in Plio-Quaternary time at a complex step-over zone on the fault. Subsidence occurred along cross-basin and transform-parallel faults in two asymmetric depocentres. The larger depocentre in the south of the basin is asymmetric towards the east, the margin along which most active transform displacement apparently occurs. The Syrian Coastal Ranges, located directly west of the Ghab basin, are a consequence of Late Cretaceous and Cenozoic regional compression, heavily modified by the Dead Sea fault system and Ghab basin formation. We prefer a model whereby the Dead Sea fault system in northwest Syria developed in Plio-Quaternary time, consistent with previously proposed models of two-phase Dead Sea fault system movement and Red Sea spreading.