The genesis of the asphalt in the Dead Sea area

The hydrocarbon occurrences of asphalts, heavy oils and oil shales in the Dead Sea area and the possible genetic relation between them have been studied. The similarity in organochemical characteristics, i.e., the elemental composition of asphaltenes, the distribution pattern of the saturated hydrocarbons and the predominance of V (over Ni)-porphyrins in both the oils and the asphalts indicate a close relation between them. On the other hand, dissimilarities in the same organochemical characteristics in both the asphalts and the oil shale exclude the hypotheses that asphalt was generated and expelled from the oil shales or that the shales were contaminated by oils. Water washing and biodegradation are considered to be the processes through which preferential depletion of hydrocarbons occurred, altering the oils to asphalts. The burial of the degraded asphalt to a relatively great depth resulted in a secondary generation of small amounts of light saturated hydrocarbons in these asphalts. The oils, which are thought to be the precursors of the asphalts, have either been flushed into the Dead Sea depression from the surrounding elevated areas or have seeped upwards from deep local accumulations in the graben.     

Biological marker characteristics of oils and asphalts from carbonate source rocks in a rapidly subsiding graben,Dead Sea,Israel

A detailed GC/MS study of biological marker compounds in the saturated and aromatic hydrocarbon fractions of oils and asphalts from the Dead Sea area, Israel, provided decisive information to the solution of a long-lasting controversy by showing that the asphalts are products of early generation in an immature stage from the same type of carbonate source rock which generated more mature oils. The asphalts are not biodegraded residues of the oils.Oils from six different wells, and asphalts from wells, outcrops, and a floating block from the Dead Sea all have very similar sterane and triterpane patterns. They all lack rearranged steranes (diasteranes) indicating a carbonate source matrix and compare reasonably well with a sample of Upper Cretaceous bituminous chalk from Nebi Musa. The main difference between the oils and the asphalts is a significantly higher triaromatic to mono- plus triaromatic steroid hydrocarbon ratio in the former. This is explained as a result of rapid subsidence and heating of their source rock close to the deep parts of the Dead Sea graben. The oils thus were generated in the more deeply buried source rock blocks under the graben fill, whereas the asphalts either originate from an immature source rock section closer to the graben rims or represent an earlier phase of generation and expulsion.This study also provides general information on the evolution of biological markers in carbonate source rocks. Low-activation-energy processes, like isomerisation of steranes, appear to occur much faster at low temperatures than in shales. The high sulfur content and less cross-linking of the biogenic organic matter into a complex kerogen structure are suggested to be responsible for this. Care should be taken when using only sterane isomerisation to assess the maturity of hydrocarbons from carbonate rocks and of carbonate-derived oils.     

Micro- and macroseismicity of the Dead Sea rift and off-coast eastern Mediterranean

The seismicity of Israel has been evaluated from documented earthquake records of the present century and two years of routine monitoring of microearthquake activity by means of eleven stations spreading from the Gulf of Elat to northern Galilee.

The Dead Sea rift asserts itself as the tectonic feature that accounts for the seismicity of our region. The activity peaks at zones where the fault branches sideways or at a junction with other fault systems. In particular, the crescent fault of Wadi Faria seems to be a zone of high strain accumulation. This is probably the site of many historical earthquakes which caused inland and coastal damage. It is thus found that the most active fault today which constitutes the greatest seismic risk to Israeli metropolitan areas extends along the Dead Sea rift from 31.2°N to 33.4°N.

The seismicity around the Dead Sea conforms with the proposed movement along en-echelon faults. While the southwest segment is presently inactive, most of the seismic activity there is limited to the neighbourhood of its eastern shore with extreme seismicity at its southern tip near the prehistorical site of Bab-a-Dara'a. The seismicity of the Arava is much lower than the Jordan-Dead Sea section. The seismicity of the Israeli coast was found to be somewhat higher than that of the Arava.     

A Tsunami Generated by a Possible Submarine Slide: Evidence for Slope Failure Triggered by the North Anatolian Fault Movement

A tsunamigenic sediment layer has been discovered in fluvio-alluvial sequences on the northern coast of the Marmara Sea, northwestern Turkey. The layer consists of unsorted silty coarse sand including terrestrial molluscs and charcoal fragments. The AMS radiometric ages of the shells have been estimated at around BC 400, AD 300, AD 400, and AD 1000. We propose that a tsunami occurred in the Marmara Sea in the middle of 11th century and invaded the fluvial plains. The older fossils were derived from the underlying horizons, and it is probable that buoyant materials such as terrestrial molluscs and charcoals were isolated from liquefied sediments during submarine sliding. Slope failure of coastal blocks triggered by fault movement generated tsunamis, which might have transported floating materials to the backshore.     

Geochemical studies on ozokerite from the Dead Sea area

Ozokerite, a natural mixture of long-chain paraffins, is found at Ein-Humar (Jordan) on the eastern escarpment of the Dead Sea. The Ein-Humar ozokerite is mainly composed of saturated n-paraffins from C₃₀ to presumably well into the C_50′s with a maximum at C₃₈. IR, NMR and chromatographic data indicate the absence of cycloparaffinic and aromatic molecules. The ozokerite is assumed to be related to the heavy asphalts and oils in the Dead Sea area. It probably forms by separation of high-molecular paraffins from non-paraffinaceous heavy oils or asphalts by geothermal heat and precipitation in the conduits due to lowering of temperature.     

Late Quaternary environmental and human events at En Gedi, reflected by the geology and archaeology of the Moringa Cave (Dead Sea area, Israel)

The Moringa Cave within Pleistocene sediments in the En Gedi area of the Dead Sea Fault Escarpment contains a sequence of various Pleistocene lacustrine deposits associated with higher-than-today lake levels at the Dead Sea basin. In addition it contains Chalcolithic remains and 5th century BC burials attributed to the Persian period, cemented and covered by Late Holocene travertine flowstone. These deposits represent a chain of Late Pleistocene and Holocene interconnected environmental and human events, echoing broader scale regional and global climate events. A major shift between depositional environments is associated with the rapid fall of Lake Lisan level during the latest Pleistocene. This exposed the sediments, providing for cave formation processes sometime between the latest Pleistocene (ca. 15 ka) and the Middle Holocene (ca. 4500 BC), eventually leading to human use of the cave. The Chalcolithic use of the cave can be related to a relatively moist desert environment, probably related to a shift in the location of the northern boundary of the Saharo-Arabian desert belt. The travertine layer was U-Th dated 2.46 ± 0.10 to 2.10 ± 0.04 ka, in agreement with the archaeological finds from the Persian period. Together with the inner consistency of the dating results, this strongly supports the reliability of the radiometric ages. The 2.46-2.10 ka travertine deposition within the presently dry cave suggests a higher recharge of the Judean Desert aquifer, correlative to a rising Dead Sea towards the end of the 1st millennium BC. This suggests a relatively moist local and regional climate facilitating human habitation of the desert.     

Preliminary mesozoic palaeomagnetic results from Israel and inferences for a microplate structure in the Lebanon

Preliminary results from a few Triassic, Jurassic and Cretaceous rocks indicate that Israel has behaved as part of the African plate during this period. Earlier palaeomagnetic results from the Lebanon, previously explained in terms of a separate Levantine plate, can be better explained in terms of differential motion between fault blocks in response to motions along the Dead Sea Fault. The available evidence allows determination of the net motions of specific fault blocks and is consistent with independent palaeogeographic indicators of the pretectonic relationship between these blocks.     

Asphalts, heavy oils, ozocerite and gases in the Dead Sea Basin

Solid, liquid and gaseous hydrocarbons occur throughout the Dead Sea Basin (Israel and Jordan) both in surface exposures and in drillings. The unaltered asphalts and heavy oils are characterized by very high sulfur content (ca. 11%) with δ³⁴S = +5% and δ¹³C = −28% to −29%, low content of n-paraffins, pristane to phytane ratio of 0.5 and by containing almost exclusively VO-porphyrins. The distribution of n-paraffins in samples from deep sources shows a smooth enveloped miximizing at C_15–20. Surface and shallow samples show clear evidence of biodegradation. The ozokerite, known only from the east side of the basin, is composed primarily of long chain n-paraffins with a maximum at C₃₉. The gases known from the southern margin of the basin are composed mostly of methane.The source for the bitumens is unknown. Two hypotheses are discussed. The first is that the asphalts and heavy oils represent an alteration products of crude oil which migrated into the basin or which might have been generated in the basin itself. The second hypothesis favors an origin from low temperature alteration of organic matter from a thermally immature source.     

Fluvial environmental contexts for archaeological sites in the Upper Khabur basin (northeastern Syria)

Today the eastern tributaries of the Upper Khabur run dry during the summer and the landscape is devoid of trees. This picture is misleading when we try to understand archaeological sites within their former environmental context. Interdisciplinary geomorphological, archaeobotanical and ostracod research on a sequence from the Wadi Jaghjagh indicates that relatively stable, perennial flow velocities occurred during the mid 4th to mid-3rd millennium BC. Evidence was found for a gallery forest and swamp belt along the Jaghjagh during the mid-4th millennium BC. Oak park woodland was present within the region in the 3rd millennium BC and probably up to at least the 3rd century AD. Shortly after 2500 BC, Jaghjagh stream velocities probably decreased or the stream bed had changed its location. Later deposits, possibly dating to the 5th century BC, indicate similar, rather stable flow of the Jaghjagh. More recently however, about ca. AD 900 or afterwards, a flashflood-like regime occurred, which may relate to deforestation. The Wadi Khanzir sediment archives reflect the flashy intermittent regime of this stream, like it still is today, with flashflood evidence dating to the first half of the Holocene and probably dating to approximately AD 400 or later. Along the Jarrah, topsoil was eroded and redeposited by the wadi sometime between 1300 and 600 BC. This may have been caused by the intensive resettlement program of this region around 800 BC. Between about 600 and 300 BC 1.5 m of clay was deposited on the plain.     

Estimating location and size of historical earthquake by combining archaeology and geology in Umm-El-Qanatir,Dead Sea Transform

We study the Byzantine-to-Ummayad (6th–8th century) archaeological site of Umm-El-Qanatir, located 10 km east of the Dead Sea Transform (DST) in northern Israel. The site was damaged by an earthquake-induced landslide, and in this work we use slope stability analysis to constrain the historical seismic acceleration that occurred along the northern segment of the DST. Umm-El-Qanatir archaeological site is located on a slope of a canyon and contains evidence for earthquake-related damage, including fallen columns and walls, horizontal shift of heavy masonry blocks, and complete burial of ceramic pots and farming tools beneath fallen ceilings. A water pool that collected spring water is displaced nearly one meter by the landslide. The artifacts from the village and the spring area indicate that people inhabited the site until the middle of the 8th century. We argue that the destruction, which forced the abandonment of Umm-El-Qanatir together with nearby settlements, was associated with the earthquake of January 18, 749 CE. In order to evaluate the ground acceleration related to the above earthquake, we back-analyze the stability of a failed slope, which cut and displaced the water-pool, using slope stability software (Slope/W). The results show that the slope is statically stable and that high values of horizontal seismic acceleration (>0.3 g) are required to induce slope failure. Subsequently, we use the Newmark displacement method to calculate the earthquake magnitude needed to cause the slope failure as a function of distance from the site. The results (attributed to the 749 CE earthquake) show that a M_W > 7.0 earthquake up to 25 km from the site could have induced the studied landslide.     

The origin of thermal waters from the eastern flank of the Dead Sea Rift Valley (western Jordan)

Thermal waters emerging along the eastern flank of the northernmost part of the Dead Sea Rift Valley close to the Yarmuk river are dilute, Ca–SO₄–(HCO₃) and Na–Cl water types with measured temperatures of 35–60 °C and estimated teperatures, according to silica solubility, of 60–110 °C. They are fed only by present‐day recharged meteoric waters (Wadi Hasa, Al Himma and North Shuna thermal baths) and by meteoric waters contaminated with saline waters (El Ma'in thermal Bath). Although they have been known for a long time, there is still dispute about their origins and the source of heat. On the basis of new chemical and isotopic analyses, the saline waters could represent residual pockets of groundwater in equilibrium with those filling the Dead Sea depression before the last retreat of Lake Lisan at 17–15 kyr bp or with the ancient seawaters of the Sedom Lagoon in the early Pleistocene, in both cases unaffected by significant evaporation processes but chemically and isotopically modified by water/rock interaction.     

Structure of the earth's crust in Jordan from potential field data

Gravity and magnetic data were collected and used to study the crustal structure of Jordan. Three new geophysical maps of Jordan were created: a Moho discontinuity map, a crystalline basement surface map, and a map showing the lowest limit of magnetic blocks. Depths of the Curie Isotherm were also calculated. Results indicate that the depth to the Moho discontinuity in Jordan varies from 32 to 33 km in the northwest to 38 km in the southeast. The basement complex rocks outcrop on the surface in the southwest but lie at about 8 km in the northeast. The Curie Isotherm (585 °C) lies at a depth of about 10 km in the area east of the Dead Sea and dips southeastward towards the Al-Sirhan (Wadi Sirhan), southeast Jordan, where it is located at 35 km depth. Local isostasy of rock masses (blocks) in Jordan does not occur. Nevertheless, this does not rule out the possible existence of isostasy in a regional scale at greater depths within the mantle.     

Evidence of Multi—Stage Hydrocarbon Charging and Biodegradation of the Silurian Asphaltic Sandstonesin the Tarim Basin,China

Asphalts distributed widely in the Silurian sandstones of the Tarim Basin include dry asphalt, soft asphalt and heavy oil. These asphaltic sandstones underwent multi-episodic sedimentary and tectonic events, and their occurrence is diverse and complex, being mixed with normal oil usually. So far, very little work has been done on the asphaltic sandstone origin and hydrocarbon charging ages. After detailed study on the Silurian sandstones, the following highlights were obtained from the analytical results: distribution of the mixed asphalt, heavy oil and normal oil in the Silurian sandstones is the result of multi-stage hydrocarbon charging from the Lower Paleozoic marine source rocks; the characters of asphalts formed from oils of different charging ages are of difference; the most important process constraining the asphaltic sandstone origin is thought to be biodegradation. This paper was financially supported by funds of Petroleum & Natural Gas Exploration in the Tarim Basin from the “State 9th Five-Year Plan Period” Key Scientific Project (No. 96-111).     

Variable behavior of the Dead Sea Fault along the southern Arava segment from GPS measurements

The Dead Sea Fault is a major strike-slip fault bounding the Arabia plate and the Sinai subplate. On the basis of three GPS campaign measurements, 12 years apart, at 19 sites distributed in Israel and Jordan, complemented by Israeli permanent stations, we compute the present-day deformation across the Wadi Arava fault, the southern segment of the Dead Sea Fault. Elastic locked-fault modelling of fault-parallel velocities provides a slip rate of 4.7 ± 0.7 mm/yr and a locking depth of 11.6 ± 5.3 km in its central part. Along its northern part, south of the Dead Sea, the simple model proposed for the central profile does not fit the velocity field well. To fit the data, two faults have to be taken into account, on both sides of the sedimentary basin of the Dead Sea, each fault accommodating ∼ 2 mm/yr. Locking depths are small (less than 2 km on the western branch, ∼ 6 km on the eastern branch). Along the southern profile, we are once again unable to fit the data using the simple model, similar to the central profile. It is very difficult to propose a velocity greater than 4 mm/yr, i.e. smaller than that along the central profile. This leads us to propose that a part of the relative movement from Sinai to Arabia is accommodated along faults located west of our profiles.     

Copper-bearing encrustations: a tool for age dating and constraining the physical–chemical regime during the late Quaternary in the Wadi Araba, southern Jordan

The alluvial–fluvial drainage system in the Wadi Araba, southern Jordan, incised into Cambrian clastic sedimentary and felsic igneous rocks giving rise to a disseminated Cu–(Mn) mineralization of diagenetic and epigenetic origin along the southern branch of the Dead Sea Transform Fault (=DSTF). During the Late Pleistocene and Holocene, the primary Cu sulfides were replaced by secondary minerals giving rise to hypogene to supergene encrustations, bearing Cu silicates, Cu carbonates, Cu oxychlorides and cupriferous vanadates. They occur in fissures, coat walls and developed even-rim/meniscus and blocky cements in the arenites near the surface. The first generation cement has been interpreted in terms of freshwater vadose hydraulic conditions, while the second-generation blocky cement of chrysocolla and malachite evolved as late cement. The Cu–Si–C fluid system within the Wadi Araba drainage system is the on-shore or subaerial facies of a regressive lacustrine regime called the “Lake Lisan Stage”, a precursor of the present-day Dead Sea. Radiocarbon dating (younger than 27,740 ± 1,570 years), oxygen-isotope-based temperature determination (hot brine-related mineralization at 60–80 °C, climate-driven mineralization at 25–30 °C) and thermodynamical calculations let to the subdivision of this secondary Cu mineralization into four stages, whose chemical and mineralogical composition was controlled by the variation of the anion complexes of silica and carbonate and the chlorine contents. The acidity of the pore water positively correlates with the degree of oxidation. The highest aridity and most intensive evaporation deduced from the thermodynamical calculations were achieved during stage 3, which is coeval with late Lake Lisan. Geogene processes causing Cu-enriched encrustations overlap with man-made manganiferous slags. The smelter feed has been derived mainly from Cu ore which developed during Late Pleistocene in the region.     

Paleoenvironmental reconstruction of Holocene coastal sediments adjacent to archaeological ruins in Aqaba,Jordan

Stratified cultural remains from the Early Roman/Nabataean to Byzantine periods in the coastal zone of Aqaba, Jordan, and analyses of thirteen sediment cores provide evidence for changes in the depositional environment during the Holocene. The overall trend in subsurface sediments is a basal marine transgressive layer overlain by a regressional sequence of embayment lagoonal sediments identified from microfossil analyses, and backshore pond, alluvium, and eolian deposits until the 1st century B.C., when mudbrick structures appear. Based on two radiocarbon dates, a brackish water coastal embayment formed prior to ca. 5900–5700 B.C. and was subsequently filled by siltation. Local tectonic subsidence along faults of the Dead Sea transform may have helped form the lagoon. Freshwater Candona sp. ostracods found in sand layers in the lagoon facies show signs of having been transported and redeposited. These data indicate that lakes or marshes were likely located inland of the study area. Supporting faunal and floral evidence for wetter climatic conditions, wetland habitats, and extensive water diversion and agricultural terraces has been excavated at late Chalcolithic (4000–3500 B.C.) sites in the Aqaba region (Khalil & Schmidt, 2009 ). By the 8th century B.C., the depositional environment along the coastal plain of Aqaba was dominated by distal alluvial fan and eolian sedimentation and the shoreline had prograded about 400m seaward. The migration of human settlements since the 8th century B.C. from the center of the valley toward the southeast may be driven by the changing course of Wadi Yutim and conditions along the coastal plain. © 2010 Wiley Periodicals, Inc.     

The seismic hazard assessment of the Dead Sea rift, Jordan

The Dead Sea fault system and its branching faults represent one of the most tectonically active regions in the Middle East. The aim of this study is to highlight the degree of hazards related to the earthquake activities associated with the Dead Sea rift, in terms of speculating the possible future earthquakes. The present investigation mainly is based on available data and vertical crustal modeling of Jordan and the Dead Sea model for the Dead Sea basin with particular emphasis of the recent earthquake activities, which occurred on December 31st, 2003 (Mc = 3.7), February 11th, 2004 (strongest Mc = 4.9 R), and March 15th, 2004 (Mc = 4). The present research examines the location of the strong events and correlates them with the various tectonic elements in the area. The source mechanism of the main shock and the aftershock events is also examined. The analyses were based on the available short period seismogram data, which was recorded at the Natural Resources Authority of Jordan, Seismological Observatory. The seismic energy appears to have migrated from the south to the north during the period from December 31st up to March 12th, where the released seismic energy showed a migration character to the southern block of the eastern side of the Dead Sea, which led the seismic event to occur on March 15th.     

Human-induced geological hazards along the Dead Sea coast

The Dead Sea is a terminal lake whose level is currently dropping at a rate of about 1 m per year due to the over exploitation of all its tributaries. The lowering started about four decades ago but geological hazards appeared more and more frequently from the end of the 1980s. The water level lowering is matched by a parallel groundwater level drop, which results in an increasing intensity of underground and surface water flow. The diagonal interface between the Dead Sea brine and the fresh groundwater is pushed downwards and seawards. Nowadays, sinkholes, subsidence, landslides and reactivated salt-karsts affect wide coastal segments. Until now, mainly infrastructures were damaged and few people/animals were injured, but the ongoing development of tourism in this very attractive situation will increase the risk if precautionary measures are not included in the development plans. This paper discusses the main observations made all around the Dead Sea and shed a light on the differences between the geological hazards of the western shore (Israel, Palestinian Authority) and the eastern shore (Jordan). It is the first attempt to bring together an overview of the human-induced geological hazards encountered along the Dead Sea coast.     

Sinkhole hazards prediction at Ghor Al Haditha, Dead Sea, Jordan: “Salt Edge” and “Tectonic” models contribution—a rebuttal to “Geophysical prediction and following development sinkholes in two Dead Sea areas, Israel and Jordan, by: Ezersky, M.G., Eppelbaum, L.V., Al-Zoubi,A.3, Keydar S., Abueladas, A-R., Akkawi E., and Medvedev, B.”

Mikhail Ezersky et al. have published the article “Geophysical prediction and following development sinkholes in two Dead Sea areas, Israel and Jordan” (February 2013) in which the paper “Salt karst and tectonics: sinkholes development along tension cracks between parallel strike-slip faults, Dead Sea, Jordan” published by Closson D, Abou Karaki N, Hallot F in 2009 (Earth Surface Processes and Landforms, 34(10), 1408–1421) is questioned. In this short paper, we propose some clarifications and discuss the criticisms of these authors.     

The thermal springs of Jordan

The thermal springs alongside Wadi Araba, Dead Sea and Jordan valley, Jordan, were investigated and sampled in a comprehensive field study of 2 weeks. Conventional physicochemical properties were measured in situ; dissolved solids and isotopic composition were analyzed. Two main spring locations on the east side of the Dead Sea were mapped. It became evident, that the hottest springs are among the closest to prominent faults; some springs are controlled by gas lift. Jordan’s hot springs are described by means of a broad hydrochemical and physicochemical data set and several figures are presented. Based on their hydrochemistry, the thermal springs are classified into four thermal provinces. Water genesis is discussed. Several geothermometers are applied to estimate reservoir temperatures. Observed discharge rate, water temperature and isotopic composition are compared with data from the literature. Although discharge and water temperature are reported to be constant over the last decades, groundwater overexploitation led to a shift of the isotopic composition, what is documented for the first time in Jordan. Thus, the effect of groundwater mining on Jordan’s hot springs can be stated as a fact.