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| Titel |
Processes of mineralization in the Hauran Basin (Syria and Jordan) and in adjoining areas |
| VerfasserIn |
Marwan Al Raggad, Salameh Elias, Nimrod Inbar, Eliahu Rosenthal, Peter Möller, Christian Siebert, Fabien Magri |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140406
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| Publikation (Nr.) |
 EGU/EGU2017-3789.pdf |
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| Zusammenfassung |
| Volcanic rocks covering vast areas in central north Jordan and in central and southern Syria
erupted during 6 different phases starting in Miocene and continuing - with major
interruptions - into the Holocene. The petrological composition of the different
flows of the Harrat ash Shaam Basalt complex is quite homogeneous with the major
minerals: Plagioclase, K-feldspar, clinopyroxene, amphibole, biotite, olivine, magnetite,
limonite, goethite, pyrite and chalcopyrite. The oldest basalts cover Cretaceous
and Paleogene sediments, which at that time formed the land surface of drainage
basins.
The basaltic aquifer contains groundwater with a wide range of salinities. They represent
a continuous sequence of increasingly mineralized groundwater originating from
precipitation over Jebel Druz flowing radially into all directions, in coincidence with the
topographic slopes. Along the flow-paths halite and gypsum are dissolved. Ca2+ not only
depends on gypsum dissolution but also increases proportionally to Mg. This may suggest
that the combination of Ca2+, Mg2+ and sulfate is a saline endmember fluid originating from
the underlying carbonate formations of the basalt. Mixing with recharge water could
explain the chemical composition of the various types of water. The signature of
dissolved gypsum and halite indicates dissolution of evaporites that might have formed
by evaporation either before the basalt covered the area or due to the hot basalts
heating up the underlying carbonates and their enclosed fluids. Evaporation of water
precipitated evaporites. Ca and Mg halides are hygroscopic, thus they are only
present in solution. Such saline water, however, has not affected the low saline
groundwater because their increase in Ca depends neither on the increase of Mg2+
nor of SO42−. This leaves the formation of clay minerals as the probably sink for
Na.
Inverse modelling applying PHREEQC with phreeq.dat database reveals that the
mineralization of groundwater increases due to dissolution of increasing amounts of halite
and gypsum which are mass-wise, the most important reactants. Concurrently, albite
increasingly precipitates. Montmorillonite, gibbsite and calcite form, whereas kaolinite is
consumed. Sulfides are oxidized. δD and δ18O of well and springs fit an evaporation line
rooted on the Ajloun MWL.
Hydrochemically, there are two sources of salts: Mixing with a saline endmember brine
and/or dissolution of evaporites. Near Jebel Druz, dissolution of evaporites dominates,
whereas mixing with a saline endmember and formation of clay minerals occur at greater
distances. |
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