Geology topics

Research about Israel

Source-linked reports with geographic coverage including Israel.

11 recordsLinked to original sources

USGS2023

Crustal structure across the central Dead Sea Transform and surrounding areas: Insights into tectonic processes in continental transforms

New geophysical profiles across the central Dead Sea Transform (DST) near the Sea of Galilee, Israel, and surrounding highlands, augmented by static stress modeling, allow us to study continental transform plate deformation. The DST separates a ∼10 km thick sedimentary column above a thinned (16–23 km) crust to the west from a ∼7 km column above a ∼30-km thick crust to the east. Crustal thinning starts under the DST, as observed also farther south, indicating that the DST is indeed located along the boundary between the Arabian plate and its continental margin. Moho step here is gradual. The DST's eastern shoulder dips westward toward the DST unlike the upward flexed shoulder observed farther south, perhaps delineating the northern limit of a thinner and hotter lithosphere. The shape of the Sea of Galilee is modeled as an asymmetric pull-apart basin formed by a left-lateral stepover of 2.6 km between slightly divergent and underlapping strike-slip fault strands dipping 70° to the west. Reflection data indicate that these strands are not connected. Several fault traces within the Sea of Galilee have previously been suggested to carry part of the relative plate motion. However, given slip along the main DST faults, Coulomb stress will increase only on fault portions in the northern part of the lake, in accord with the geographical distribution of seismicity, suggesting that these faults are likely secondary. Mismatch between the DST strand locations in the geophysical profiles and the subsidence model, may reflect temporal changes in fault geometry.

Tectonics↗

USGS2021

Stormwater systems as a source of marine debris: A case study from the Mediterranean coast of Israel

Drainage (or stormwater) systems are a potential source of marine debris. Approximately 67 km (33%) of the land along the Mediterranean coast of Israel is considered urban, covered by concrete and asphalt. The purpose of the present pilot study was to determine the composition of the solid waste in a drainage system and evaluate to what extent municipal sources contribute to marine debris. We sampled the waste in Netanya, a medium-size city (245,000 residents) on the central Mediterranean coast of Israel. Samples were taken from seven street stormwater receptacles prior to the first significant rain and then on the beach near a drainage outlet, a few hours after this substantial rain. In terms of composition of the debris, paper, cigarette butts, and sanitary items made up a higher proportion of the drainage system debris than those items did on the beach. In contrast, single-use items, polystyrene pieces, bottle caps, and plastic drinking bottles composed more of the debris on the beaches compared to the debris in the drainage system. Overall, we found that municipal stormwater systems contribute significant amounts of solid waste to marine debris on Israeli beaches. Preventing the waste from reaching the streets might help reduce marine debris on the beaches, especially at the beginning of the rainy season. There are multiple solutions, but all will require creativity and resources and constant maintenance. Educating the public to prevent disposal of solid waste items in the street is also important as a way to reduce terrestrial as well as marine debris.

Journal of Coastal Conservation↗

USGS2019

Semi-automated bathymetric spectral decomposition delineates the impact of mass wasting on the morphological evolution of the continental slope, offshore Israel

Understanding continental slope morphological evolution is essential for predicting depositional systems and reservoirs in the adjacent basin. However, present-day slope seafloor-morphology is complicated by shaping processes, which are not readily separable through pure bathymetric analysis. This study aims to explore the utility of bathymetric spectral decomposition in order to separate and characterize interleaved seafloor imprints of mass wasting, and for clarifying their role in the morphological evolution of the slope of the southeastern Mediterranean Sea passive continental margin. Controlled by margin-parallel transport of Nilotic sediments from the south, this margin exhibits an intertwined variety of mass transport features. Our spectral decomposition of digital bathymetry, integrated with interpretation of seismic reflection data, highlights the long-term shape of the slope and separates the observed mass transport elements into several genetic groups: 1) a series of ~25 km wide, now buried slide scars and lobes; 2) slope-parallel bathymetric scarps representing shallow faults; 3) slope-perpendicular, open slope slide scars; .4) bathymetric roughness representing open slope debris lobes; 5) slope confined gullies. Our results provide a multi-scale view of the interplay between sliding and erosive flows, and shallow faulting accommodating internal deformation and salt retreat, in the evolution of continental slope morphology. The base of the slope and focused disturbances are controlled by relatively deep-seated (~1 km) salt retreat, and therefore mimic the Messinian base of slope. The top of the open slope is delimited by faults, accommodating internal collapse of the margin. The now-buried slide scars appear to have been cohesive and slope-confined and have mostly nucleated along the upper slope faults. The collapse of sediments infilling accommodation spaces created by these buried slides nucleated the more recent open slope slides. The open slope slides transported ~10 km3 of sediments, depositing on the lower slope and basin edge an average sediments thickness of ~3 m. Such a thickness is a significant fraction of the sediments accumulated along the base of the studied continental slope within the last <50 ka. South to north changes in population and size distribution of the open-slope slide scars highlight their role in counterbalancing the northwards diminishing sediment supply and helping to maintain a long-term steady-state bathymetric profile. The latest phase slope-confined gullies were presumably created by channeling of bottom currents into recent slide-scar depressions, possibly establishing incipient canyon headword erosion.

Marine Geology↗

USGS2019

Nearshore survey and cleanup of benthic marine debris using citizen science divers along the Mediterranean coast of Israel

Information on marine debris along the Mediterranean coast of Israel, especially on the seafloor, is limited. Many recreational divers are enthusiasts of marine conservation and can thus contribute to data collection which does not require highly specialized training. The Society for the Protection of Nature in Israel together with The Israeli Diving Federation established the diver volunteer program “Sea Guard” (“Mishmar Hayam” in Hebrew), which supports marine conservation through citizen science. The divers were trained in marine ecology and survey methods to conduct independent surveys and lead underwater cleanups. For the first time, we have described the patterns of benthic debris density and composition in the nearshore environment of the southeastern part of the Mediterranean Sea. We found that benthic marine debris in the nearshore along the Israeli Mediterranean coast is primarily plastic, likely originating from the use of local beaches. Fishing, boating and domestic activities also play an important role as sources for marine debris. The currents' regime prevented the debris from accumulating on the seafloor in the nearshore environment, with the exception of several “debris traps”. Our findings will be useful for the development of programs to improve coastal waste management.

Ocean and Coastal Management↗

USGS2017

Sources, composition and spatial distribution of marine debris along the Mediterranean coast of Israel

Marine debris (litter) is a complex problem that affects human activities and the marine environment worldwide. The Clean Coast Program in Israel has had some success in keeping most of the coasts clean most of the time, but without understanding the mechanisms of accumulation of marine debris on the coasts of Israel. In 2012, we initiated a study to characterize the types of marine debris, its origins and spatial distribution. Nineteen surveys were done from June 2012 to March 2015 on eight beaches that spanned the coast of Israel. Average debris density was 12.1 items per 100 m 2 and 90% of the items were plastic. The top debris categories were food wrappers and disposables, plastic bags and cigarette butts. However, there was variation in the top debris categories among the beaches indicating that a flexible approach with multiple options will be important when addressing the marine debris problem.

Mediterranean coast↗

USGS2010

Sources of aerosol nitrate to the Gulf of Aqaba: Evidence from δ15N and δ18O of nitrate and trace metal chemistry

The nitrogen (N) and oxygen (O) isotopic composition (δ 15 N and δ 18 O) of water soluble aerosol nitrate was measured in aerosol samples collected in Eilat, Israel, from August 2003 to November 2004. During this period δ 15 N values ranged from − 6.9‰ to + 1.9‰ and δ 18 O from + 65.1‰ to + 84.9‰ and exhibited strong seasonal variability with higher average δ 15 N values observed in the summer and higher δ 18 O values in the winter. Nitrate isotopic composition was compared with bulk chemical composition and extractable ion and trace metals on co-collected samples linking nitrate isotopic composition to various sources of aerosols to this region. Atmospheric processes impacting the isotopic signatures of nitrate were also considered. Based on back trajectory analyses, the majority of NO 3 − came from air masses originating over the Mediterranean Sea (34%), Western Europe (20%) and the local Negev desert (19%), which contain a larger anthropogenic imprint compared to southern and eastern air masses which are dominated by mineral dust. The potential role of reactive mineral dust aerosols as a regulator of NO 3 − isotopic composition is considered; however, based on factor analysis, neither δ 15 N nor δ 18 O were associated with mineral dust components (such as Fe or Al), but rather with anthropogenic indicators such as Cu, Cd, P and Pb. Seasonality in primary NO x cycling reactions driven by seasonal changes in solar radiation, relative humidity and temperature also influence the observed isotopic signatures. The isotope data, together with trace element analysis, suggests that seasonal variations in both δ 15 N NO3 and δ 18 O NO3 are related to both NO x source and transport processes as well as NO x chemical reactions in the atmosphere. The flux-weighted δ 15 N of aerosol NO 3 − in this area averaged − 2.6‰ making aerosol deposition a substantial contributor of low δ 15 N nitrogen to the oligotrophic waters of the Gulf of Aqaba. Thus, while the flux of atmospheric N to oligotrophic marine systems is smaller than the upward flux of NO 3 − from deep water, it nonetheless represents an important source of new N having a low δ 15 N. Further, if this low δ 15 N signature is not considered, it could interfere with N-fixation estimates based on isotopic composition of dissolved nitrate or particulate organic nitrogen. Thus, atmospheric deposition should be constrained for accurate estimates of marine N-fixation when based on δ 15 N in the ocean. Indeed, in the Gulf of Aqaba, low upper water δ 15 N NO3 values could be related to inputs of atmospheric NO 3 − as well as N-fixation.

Gulf of Aqaba, Eliat↗

USGS2007

Role of aquifer heterogeneity in fresh groundwater discharge and seawater recycling: An example from the Carmel coast, Israel

A case study is shown in which the pattern of submarine groundwater discharge and of seawater recycling is controlled by local hydrogeological variability. The coastal aquifer in Dor Bay is composed of two units: a partly confined calcaranitic sandstone (Kurkar) and an overlying loose sand. Groundwater in the Kurkar has elevated activities of 222 Rn (∼390 dpm/L) and relatively low 224 Ra/ 223 Ra activity ratios (3–4), while the sand groundwater is significantly less radiogenic (6–90 dpm/L) and shows higher 224 Ra/ 223 Ra ratios. Groundwater discharging from sand-covered areas of the bay has salinities of 16–31 and an average 222 Rn activity of 168 dpm/L, which lies on a mixing line between Rn-rich Kurkar fresh water and Rn-poor seawater. Another key observation is that seawater infiltrates to some extent into onshore sand groundwater, while the fresh water within the submarine Kurkar can be traced up to 40 m offshore. This implies that while fresh water mainly discharges from the Kurkar unit, seawater recycling is limited to the loose sand, and that the discharge from sand-covered areas is a mixture of Kurkar water with recycled seawater. Advection rates from the bay floor were calculated from Rn time series and found to vary between 0 and 36 cm/d, correlating negatively with bay water depth. The average flux was 8.1 cm/d, and it did not seem to change much during March, May, and July 2006. The average amount of fresh water discharging to the bay was 5.0 m 3 /d per meter of shoreline. Radon activity in the sand groundwater also fluctuates due to influx of Kurkar-type groundwater.

Carmel Coast, Dor Bay↗

USGS2007

New isotopic evidence for the origin of groundwater from the Nubian Sandstone Aquifer in the Negev, Israel

The geochemistry and isotopic composition (H, O, S, O sulfate , C, Sr) of groundwater from the Nubian Sandstone (Kurnub Group) aquifer in the Negev, Israel, were investigated in an attempt to reconstruct the origin of the water and solutes, evaluate modes of water–rock interactions, and determine mean residence times of the water. The results indicate multiple recharge events into the Nubian sandstone aquifer characterized by distinctive isotope signatures and deuterium excess values. In the northeastern Negev, groundwater was identified with deuterium excess values of ∼16‰, which suggests local recharge via unconfined areas of the aquifer in the Negev anticline systems. The δ 18 O H2O and δ 2 H values (−6.5‰ and −35.4‰) of this groundwater are higher than those of groundwater in the Sinai Peninsula and southern Arava valley (−7.5‰ and −48.3‰) that likewise have lower deuterium excess values of ∼10‰. Based on the geochemical differences between groundwater in the unconfined and confined zones of the aquifer, a conceptual geochemical model for the evolution of the groundwater in the Nubian sandstone aquifer has been reconstructed. The isotopic composition of shallow groundwater from the unconfined zone indicates that during recharge oxidation of pyrite to SO 4 ( δ 34 S SO4 ∼−13‰; δ 18 O SO4 ∼+7.7‰) and dissolution of CaCO 3 ( 87 Sr/ 86 Sr ∼0.70787; δ 13 C DIC = −3.7‰) occur. In the confined zone of the aquifer, bacterial SO 4 reduction removes a significant part of dissolved SO 4 2 - "> SO42- , thereby modifying its isotopic composition ( δ 34 S SO4 ∼−2‰; δ 18 O SO4 ∼+8.5‰) and liberating dissolved inorganic C that contains little or no radiocarbon ( 14 C-free) with low δ 13 C DIC values (<−12‰). In addition to local recharge, the Sr and S isotopic data revealed contribution of external groundwater sources to the Nubian Sandstone aquifer, resulting in further modifications of the groundwater chemical and isotopic signatures. In the northeastern Negev, it is shown that SO 4 -rich groundwater from the underlying Jurassic aquifer contributes significantly to the salt budget of the Nubian Sandstone aquifer. The unique chemical and isotopic composition of the Jurassic groundwater ( δ 34 S SO4 ∼ +14‰; δ 18 O SO4 ∼ 14‰; 87 Sr/ 86 Sr ∼0.70764) is interpreted as reflecting dissolution of Late Triassic marine gypsum deposits. In the southern Arava Valley the authors postulate that SO 4 -rich groundwater with distinctively high Br/Cl (3 × 10 −3 ) low 87 Sr/ 86 Sr (0.70734), and high δ 34 S SO4 values (+15‰) is derived from mixing with underlying brines from the Paleozoic units. The radiocarbon measurements reveal low 14 C activities (0.2–5.8 pmc) in both the northeastern Negev and southern Arava Valley. Taking into account dissolution of carbonate rocks and bacterial SO 4 reduction in the unconfined area, estimated mean residence times of groundwater in the confined zone in the northeastern Negev are on the order of 21–38 ka, which suggests recharge predominantly during the last glacial period. The 14 C signal in groundwater from the southern Arava Valley is equally low but due to evidence for mixing with external water sources the residence time estimates are questionable.

Applied Geochemistry↗

USGS2000

Transient groundwater-lake interactions in a continental rift: Sea of Galilee, Israel

The Sea of Galilee, located in the northern part of the Dead Sea rift, is currently an intermediate fresh-water lake. It is postulated that during a short highstand phase of former Lake Lisan in the late Pleistocene, saline water percolated into the subsurface. Since its recession from the Kinarot basin and the instantaneous formation of the fresh-water lake (the Sea of Galilee), the previously intruded brine has been flushed backward toward the lake. Numerical simulations solving the coupled equations of fluid flow and of solute and heat transport are applied to examine the feasibility of this hypothesis. A sensitivity analysis shows that the major parameters controlling basin hydrodynamics are lake-water salinity, aquifer permeability, and aquifer anisotropy. Results show that a highstand period of 3000 yr in Lake Lisan was sufficient for saline water to percolate deep into the subsurface. Because of different aquifer permeabilities on both sides of the rift, brine percolated into a aquifers on the western margin, whereas percolation was negligible on the eastern side. In the simulation, after the occupation of the basin by the Sea of Galilee, the invading saline water was leached backward by a topography-driven flow. It is suggested that the percolating brine on the western side reacted with limestone at depth to form epigenetic dolomite at elevated temperatures. Therefore, groundwater discharging along the western shores of the Sea of Galilee has a higher calcium to magnesium ratio than groundwater on the eastern side.

Lake Tiberias, Sea of Galilee↗

USGS1996

Gravity field over the Sea of Galilee: Evidence for a composite basin along a transform fault

The Sea of Galilee (Lake Kinneret) is located at the northern portion of the Kinneret-Bet Shean basin, in the northern Dead Sea transform. Three hundred kilometers of continuous marine gravity data were collected in the lake and integrated with land gravity data to a distance of more than 20 km around the lake. Analyses of the gravity data resulted in a free-air anomaly map, a variable density Bouguer anomaly map, and a horizontal first derivative map of the Bouguer anomaly. These maps, together with gravity models of profiles across the lake and the area south of it, were used to infer the geometry of the basins in this region and the main faults of the transform system. The Sea of Galilee can be divided into two units. The southern half is a pull-apart that extends to the Kinarot Valley, south of the lake, whereas the northern half was formed by rotational opening and transverse normal faults. The deepest part of the basinal area is located well south of the deepest bathymetric depression. This implies that the northeastern part of the lake, where the bathymetry is the deepest, is a young feature that is actively subsiding now. The pull-apart basin is almost symmetrical in the southern part of the lake and in the Kinarot Valley south of the lake. This suggests that the basin here is bounded by strike-slip faults on both sides. The eastern boundary fault extends to the northern part of the lake, while the western fault does not cross the northern part. The main factor controlling the structural complexity of this area is the interaction of the Dead Sea transform with a subperpendicular fault system and rotated blocks.

Sea of Galilee↗

USGS1964

Relation of temperature distribution to ground-water movement in carbonate rocks of central Israel

The Cenomanian-Turonian formations of central Israel constitute a highly permeable dolomite and limestone aquifer. In this area it is on the west limb of an anticlinorium that trends north-northeast, and it contains water under artesian pressure. A graph of water temperatures and well depths suggests that there is a very small vertical temperature gradient in local segments of the aquifer. The small gradient is believed to result from a large vertical component of flow that tends to equalize the vertical temperature distribution . On a regional scale the apparent horizontal temperature distribution indicates a westward increase with increasing depth of the aquifer, suggesting a manifestation of the regional geothermal gradient. The westward increase in temperature also implies that the lateral component of flow may be in the normal range for artesian carbonate - rock aquifers whose pores consist mainly of solution cavities. Locally, pumping appears to have affected the temperature distribution by modifying the natural flow pattern. In parts of the most intensively developed area, the aquifer is hydraulically connected with overlying coastal-plain deposits, and some cooler water has been induced to move into the aquifer from this source. At three other areas, pumping has resulted in an apparent horizontal shift of the isotherms on a temperature - distribution map. The data suggest that the spatial distribution of temperature may be used to determine some of the flow characteristics of carbonate - rock aquifers.

Geological Society of America Bulletin↗