ALBERT

Description: According to spider patterns five different types of thermal groundwater are distinguishable in Jordan. Each spider diagram comprises groups of elements which characterise soluble minerals of the aquifer such as halite, calcite, and gypsum, and leachable fractions of trace elements such as B, Ba, Br, Y, Cs, Rb, and U. In Jordan, mineralization of groundwater is largely controlled by dissolution of halite, carbonates, gypsum, and leaching diverse K-bearing minerals. Caused by interaction with Neogene basalts, limestones are silicified and mineralogically altered. Groundwater from these aquifers significantly differs in composition from those of the unaltered limestone aquifers. The benefit of spider patterns is that they visualise (i) chemical differences in groundwater from essentially similar aquifer rock such as young, old or thermally altered limestones and (ii) chemical similarities of groundwater produced from different geological formations. In contrast to spider patterns, ionic ratios widely overlap and do not unequivocally allow grouping of groundwater. 34S(sulfate) varies between -4 and +29 . Low values prove the presence of oxidised sulfides either of igneous origin or from sedimentary rocks. The spread of 34S is caused by mixing with marine sulfate. All analysed water from Paleozoic rocks is replenished from younger aquifers. Considerable transaquifer flow exists more or less all over the Jordan territory. Salinization of sandstone-bound water along the rift escarpment is caused by a Na+-K+-SO42--HCO3- brine, whereas the wells Al Umari 1 and Wadi Araba 5 are affected by the presence of a Ca2+-Cl- brine.

Description: Four types of thermal groundwater in Jordan were distinguished by Y and rare earth elements (REY) distribution patterns. Complementary to the stratigraphic origin of water in springs or of wells, REY patterns identify either recharge areas covered by basalt, limestones or sandstone, or interaction with basalt-limestone contact zones. This hydrochemical grouping does not always correspond with “common geological knowledge” of the aquifer lithology of the thermal water. Therefore, comparison of the hydrochemical signatures of REY patterns and the lithological source of water yield insight into transaquifer flow. Out of 44 analysed groundwater, 18 indicated down- and 3 upflow of water the latter due to step faults near the Rift system. During transaquifer flow REY patterns of groundwater from basalts and gypsum beds or gypsum-cemented sandstones are not changed by subsequent interaction with limestones, whereas in groundwater originating from dissolution of chalk and limestones REY patterns are adjusted to those typical for gypsum-bearing sediments. Cross plots of d18O vs. d2H reveal essentially two trends. The main trend of water from limestone aquifers define a mixing line of past to recent meteoric water with negligible contributions of Pleistocene water. Some water from Eocene aquifers plot on the local Mediterranean meteoric water line, others plot together with water from sandstone aquifers at enhanced d18O values due to hydrothermal overprinting.

Description: Changes in the concentrations of major, some minor and trace elements occurring in both surface and groundwater of the lower Jordan River–Dead Sea drainage basin have been investigated in order to identify the characteristics of the regional aquifers and their recharge areas. Spider patterns of elements and rare earth distribution patterns pinpoint the characteristic chemical features of groundwater. As compared to seawater, the high Br/Cl ratios in groundwater are caused either by high Br/Cl ratios in precipitation, by leaching of Br from bituminous matter or by mixing with brines beyond the epsomite stage. The locations of groundwater samples with enhanced B contents coincide with the distribution of gypsum in the beds of the Lisan Formation, which produces water with nearly constant B/SO42− molar ratios. Aeolian distribution of the unconsolidated Lisan sediments influences the B/SO4 ratio in the area of Lake Tiberias and in the Jordan Highlands. The high Gd anomaly in the Dead Sea water is of geologic origin whereas that in the Jordan River and in Nahal (stream) Qidron is largely anthropogenic. The anthropogenic Gd input to the Dead Sea is insignificant compared to the actual amount in the water of the Dead Sea. Hot saline water encountered along the western shores of the Dead Sea with high Gd anomalies indicate that they contain large amounts of ancient Dead Sea water that mix (as hot ascending brines) with fresh water. The recharge area of groundwater in the lower Jordan Valley extends largely over limestone and dolomite outcrops of the Upper Cretaceous Judea Group. Weathering of locally underlying Lower Cretaceous volcanics in the area of Pezael–Beqaot, and Argaman yield groundwater with δ34S(SO42−) values ranging from − 2 to + 4‰. The presence of sulphide-bearing bodies in this area is attested to magnetic anomalies detected at depths of several kilometres. δ34S(SO42−) indicates very deep groundwater circulation. High δ34S(SO42−) 〉 15‰ is typical for marine sulphates from the Judea and Avedat Group limestone. The springs located along the northwestern shore of the Dead Sea discharge water replenished on the eastern Judea Mountains. The increase in the salinity of this water is due to brines flushed from sediments and from adjacent sedimentary rocks, which host entrapped brines from the precursors of the Dead Sea formed during the late stages of Lake Lisan. Fresher water flushes out these residual brines as a result of falling sea level. Salinity increase in groundwater is also affected by the ascent of deep-seated hot brines from pre-Sedom periods along the Rift faults. Calculations of mixing between fresh and highly saline end-members show that leaching of anhydrite from sediments, precipitation of calcite, formation of dolomite, albitization of plagioclase and ion exchange with abundant clay minerals control the major-element composition of the saline groundwater.