The paleoenvironment and the evolution of brines in the Jordan-Dead Sea transform and in adjoining areas

One of the most important processes leading to the deterioration of groundwater in Israel is the migration of brines penetrating into fresh groundwater bodies. Such manifestations occur at an ever increasing frequency and in unexpected locations. The hydrochemistry of these processes reveals the possibility of involvement of several types of brines. The distribution and the hydrostratigraphic sequence of the brines is correlated with the evolution of paleoenvironments during the geological history of the region. Several major phases of brine and evaporite formation are discerned: The earliest phase occurred in the Paleozoic–Early Mesozoic (Yam Suf–Ramon–Lower Arad Groups) during which brines were generated by dissolution of evaporites. The second major phase in the evolution of brines occurred during the Mio-Pliocene. In the western areas of the country, the brines were generated mainly by the post-Messinian ingression of seawater which dissolved evaporites and reacted with the invaded rock sequence. In the Rift and in adjoining areas, the dominant brine was the final product of the evaporation of an inland marine lagoon (the Sdom Sea) which penetrated into an environment prevalently built of previously formed rocks and, particularly of clastic beds filling at that time, the nascent rift. From this evaporating lagoon precipitated evaporates, the dissolution of which produced brines. A further step in the hydrochemical evolution in the Rift was the creation of the Lisan Lake, which became progressively saline, probably as the result of dissolution and flushing of salts derived from the previous hypersaline Sdom Sea. The contemporary phase in the Rift is characterized by an ongoing process of flushing-out of residual brines and dissolution of evaporites by currently recharged fresh water. Throughout the geological history of the area, four major periods of flushing stand out. These occurred between the Triassic and the Jurassic, at the end of the Jurassic, as the result of the Oligocene uplift and as part of the Messinian event. As the result of these processes, the rock-sequences were flushed off previously formed brines and evaporites and were “made ready” for following generations of liquids.     

Chemical evolution of saline waters in the Jordan-Dead Sea transform and in adjoining areas

The Ca–Mg relationship in groundwaters strongly points to the overall dolomitization and local albitization. The Mg/Ca ratios reveal two trends by which saline waters develop: increase of Mg/Ca ratio by evaporation and decreasing Mg/Ca ratios due to dolomitization and albitization. Br/Cl vs. Na/Cl ratios demonstrate that albitization does not play a major role which leaves dolomitization to be the main source for decreasing Mg/Ca ratios in saline waters. In the eastern and southern Region of Lake Kinneret, salinization occurs by mixing with a Ca/Mg molar ratio <1 brine (Ha’On type). Along the western shoreline of the Lake, a Ca/Mg > 1 dominates, which developed by the albitization of plagioclase in abundant mafic volcanics and the dolomitization of limestones. The most saline groundwater of the Tabgha-, Fuliya-, and Tiberias clusters could be regional derivatives of at least two mother brines: in diluted form one is represented by Ha’On water, the other is a Na-rich brine of the Zemah type. Additionally, a deep-seated Ca-dominant brine may ascend along the fractures on the western side of Lake Kinneret, which is absent on the eastern side. Groundwaters of the Lower Jordan Valley are chemically different on both sides of the Jordan River, indicating that the exchange of water is insignificant. All saline waters from the Dead Sea and its surroundings represent a complex mixture of brines, and precipitation and local dissolution of halite and gypsum. Many wells of the Arava/Araba Valley pump groundwater from the Upper Cretaceous limestone aquifer, the origin of the water is actually from the Lower Cretaceous Kurnub Group sandstones. Groundwater drawn from the Quaternary alluvial fill either originates from Kurnub Group sandstones (Eilat 108, Yaalon 117) or from altered limestones of the Judea Group. The origin of these waters is from floods flowing through wadis incised into calcareous formations of the Judea Group. On the other hand, as a result of step-faulting, hydraulic contact is locally established between the Kurnub- and the Judea Groups aquifers facilitating the inter-aquifer flow of the confined Kurnub paleowater into the karstic formations of the Judea Group. Two periods of Neogene brine formation are considered: the post-Messinan inland lagoon resulting in drying up of the Sdom Sea and the evaporation of the Pleistocene Samra Lake, which went further through the stage of Lake Lisan to the present Dead Sea. For the first period, major element hydrochemistry suggests that the saline waters and brines in the Jordan-Dead Sea–Arava Valley transform evolved from the gradual evaporation of an accumulating mixture of sea-, ground-, and surface water. Due to the precipitation of carbonates, gypsum, and halite, such an evaporating primary water body was strongly enriched in Mg, Br, and B and shows high molar ratios of Br/Cl, B/Cl, and Mg/Ca but low Na/Cl ratios. The development of the Br/Cl ratio is chemically modelled, showing that indeed brine development is explicable that way. Along with the evaporation brine, evaporites formed which are leached by infiltrating fresh water yielding secondary brines with Na/Cl ratios of 1. When primary brines infiltrated the sub-surface, they were subjected to Mg–Ca exchange in limestones (dolomitization) and to chloritization and albitization in basic igneous rocks turning them into Ca-Cl brines. These tertiary brines are omnipresent in the Rift. The brines of the late Lisan and Dead Sea were generated by evaporating drainage waters, which leached halite, gypsum, and carbonates from the soil and from the sub-surface. All these brines are still being flushed out by meteoric water, resulting in saline groundwaters. This flushing is regionally enhanced by intensive groundwater exploitation. In variable proportions, the Neogene and late Lisan Lake and Recent Dead Sea brines have to be considered as the most serious sources of salinization of groundwaters in the Rift. Deep-seated pre-Sdom brines cannot strictly be excluded, but if active they play a negligible role only. An erratum to this article can be found at     

Sea-level anticyclogenesis affecting Mediterranean weather

A statistical investigation is made of anticyclogenesis in the Mediterranean and European region during the period 1928 to 1937 inclusive; the distributions of anticyclogenesis in time and space are obtained and described.

---

Zusammenfassung Es wird eine statistische Untersuchung über die Bildung von Antizyklonen im Gebiet des Mittelmeers und Europas während der Periode 1928–1937 durchgeführt; dabei wird die zeitliche und räumliche Verteilung der Antizyklogenese abgeleitet und erörtert.

---

Résumé L'auteur soumet à un examen statistique la genèse des anticyclones qui se sont formés dans la région de la Méditerranée et de l'Europe de 1928 à 1937; par cette procédure il déduit et décrit l'anticyclogénèse dans le temps et l'espace.

---

---

With 7 Figures

---

This research was supported by the Geophysics Research Directorate of the U. S. Air Force Cambridge Research Center, under contract No. AF 19 (122)-466.     

Advertent/inadvertent changes in the spatial distribution of rainfall in the central coastal plain of Israel

Analysis of recent rainfall normals reveals an unusual spatial pattern where the rainfall increases with the distance from the sea over the central coastal plain of Israel. Applying a multiple regression technique separately to rainfall amounts for the two randomized experiments of cloud seeding of seeded days and not seeded days, leads to the conclusion that the inadvertent influence of recent urbanization processes along the coastal plain are the cause of this phenomenon, rather than the advertent artificial cloud seeding. The seeding effect at the target area, on the other hand, seems to increase the inhomogeneity of the spatial structure of the rainfall distribution.     

Thermomineral waters of Ca-chloride composition: review of diagnostics and of brine evolution

 Ca-chloride waters are defined as those in which Q=rCa/r(SO₄+HCO₃)>1, rNa/rCl<0.80, rMg/rCa<0.5 and wCl/wBr<286 (r=meq l^–1 and w=mg l^–1). Throughout the last 50 years, different models for the formation of such waters have been suggested. These models include: (1) filtration through semipermeable membranes under conditions of highly compacted argillaceous sediments, (2) deaquation of seawater by evaporation and/or by freezing followed by dolomitization, (3) hydrolysis of plagioclase and biotites in igneous metamorphic rock masses, (4) radiolytic modification of residual metamorphic fluids, and (5) dissolution of chalks followed by ion exchange on smectites. The better understanding of processes and of natural environments leading to the evolution and natural occurrence of such brines, is imperative for the prospection and further sustained exploitation of such waters. Received: 11 October 1996 · Accepted: 24 February 1997     

Spatial distribution of surface properties,runoff generation and landscape development in the Zin Valley Badlands,northern Negev,Israel

In?ltration tests, soil mapping and soil property analysis were used to assess the effect of within‐storm rainfall conditions on spatial patterns of surface characteristics relevant for runoff generation, continuity and erosion in the Zin Valley Badlands. Runoff and erosion differ strongly between ridges and slopes. Soils at both locations are susceptible to sealing, but on the sideslopes deep desiccation cracks inhibit continuous ?ow, even during high magnitude rainstorms. The discontinuous nature of runoff has a feedback on surface conditions. Erosion on the ridges maintains shallow soils prone to sealing while in?ltration and deposition on the sideslopes enhance soil depth, a prerequisite for stable desiccation cracks. Some runoff generated on the ridges is transmitted to the valley via rills. On straight sideslopes, rills are single and often discontinuous, indicating limited frequency of continuous runoff. Along concave valley heads, rill systems are well integrated and continuous, concentrating runoff and reducing in?ltration losses along slopes. The longitudinal, V‐shaped valley morphology of small catchments in the Zin Valley Badlands re?ects the long‐term effect of different erosion rates in valley heads and on sideslopes. Over time, valley incision lengthened the sideslopes, reducing the portion of annual rainfall that was runoff‐effective. Once sideslopes reached a critical length that inhibited frequent continuous ?ow, a colluvium with an increased in?ltration capacity developed, reducing runoff frequency even further. Consequently, erosion on the valley sideslopes decreased. Continuous ?ow from ridges to the valley channel remained more common in integrated rill systems in concavities and valley heads, leading to more erosion and retreat of the valley heads. The spatial patterns of runoff and erosion in the Zin Valley Badlands demonstrate that landscape development is strongly affected by processes that lead to differentiation of soil properties on hillslopes with uniform lithology. The patterns of surface characteristics and their role in landscape development are strongly dependent on rainfall conditions, highlighting the need for geomorphologists to identify the dynamic spatial and temporal scales relevant for landscape development. Copyright © 2004 John Wiley & Sons, Ltd.     

The Kerguelen Province revisited: Additional constraints on the early development of the Southeast Indian Ocean

The Kerguelen Province, consisting of two oceanic plateaus (Kerguelen, Broken Ridge) and three basins (Enderby, Labuan and Diamantina), covers a large area of ocean floor in the southeast Indian Ocean. As very few magnetic anomalies have been identified in this area and only a few basement ages from the Kerguelen Plateau are known, reconstruction models of the Kerguelen Province are not well constrained. In an effort to gain more understanding about the evolution of this area, we have used satellite gravity to identify additional fracture zones. As they are likely to be associated with high frequency and low amplitude gravity anomalies, we have computed the vertical derivative map instead of the regular satellite gravity map. Using this approach, we have identified a series of fracture zones in the Enderby Basin, which are aligned with the Mesozoic fracture zones in the Perth Basin and converge to the Kerguelen Fracture Zone. In the conjugate Bay of Bengal, we traced an equivalent pattern of fracture zones which, together, better constrain the early evolution of this part of the Indian Ocean. Synthesis of these images and the other available data from the Kerguelen Province, suggests that the spreading of India from both Australia and Antarctica is closely related. Spreading between the three continents appears to have begun about the same time, in the early Cretaceous and thus, the accretion of some parts of the Kerguelen Province must have occurred before the onset of the quiet magnetic period at 118 Ma. At about 96–99 Ma, when the spreading direction in the Indian Ocean had changed into a N-S direction, it also took place throughout the Kerguelen Province. We find that previously proposed slow spreading in the Diamantina Zone and Labuan Basins, between 96–99 Ma and the initiation of the Southeast Indian Ridge at 43 Ma, could not have taken place. Furthermore, we suggest that there is growing evidence that the same is true for spreading in the eastward continuation of the Diamantina Zone and Labuan Basin, between Australia and Antarctica. Initiation of spreading in this area is likely to be contemporaneous with the spreading in the Kerguelen Province and, thus, older than 96–99 Ma. This revised version was published online in November 2006 with corrections to the Cover Date.