TY - JOUR
T1 - Present and paleo-hydrogeological reconstruction of a complex deep groundwater system in a tectonically active region (Golan Heights, Middle East)
AU - Ben-nun Levanon, Hadas
AU - Burg, Avihu
AU - Gavrieli, Ittai
AU - Rosenberg, Yoav O.
AU - Gersman, Ronen
AU - Bartov, Yuval
AU - Livshitz, Yakov
AU - Starinsky, Avraham
AU - Reznik, Itay J.
N1 - Publisher Copyright:
© The Author(s) 2024.
PY - 2024/6
Y1 - 2024/6
N2 - The geochemical and isotopic composition of deep groundwater in sedimentary aquitards reveals a complex paleo-hydrological system affected by intensive tectonic activity. Water samples collected from deep research boreholes in the Golan Heights (Middle East) exhibit a unique combination of high salinity (>2,000 mg/L Cl) with low Na/Cl (<0.7) and Mg/Ca (<0.3) equivalent ratios, calcium chloride water type [Ca > (HCO3 + SO4)], relatively low δ18OVSMOW and δ2HVSMOW values (–7 and –42‰, respectively), and enriched 87Sr/86Sr ratios compared to the host rocks. The salinity source is related to ancient lagoonary hypersaline brines (10–5 Ma) that existed along the Dead Sea Rift (DSR). These brines intruded into the rocks surrounding the DSR and, based on the current study, also extended away from the rift. Following their subsurface intrusion, the brines have been gradually diluted by 18O- and 2H-depleted freshwater recharged at high elevations, nowadays leaving only traces of the brines that originally intruded. It is also shown that variable hydraulic conductivities in different formations control the dilution rates and subsequently the preservation of the entrapped brines. A paleo-hydrological reconstruction is provided to demonstrate intrusion and backflow dynamics and also the relationship to freshwater dilution, which was triggered by a tectonically active basin of the nearby continental DSR. Brines that initially migrated from the rift have since been gradually flushed back to the rift through the current natural outlets. As the system discharges, it mixes and converges with a separate hydrogeological system, while still preserving some of the geochemical signals of the ancient brines.
AB - The geochemical and isotopic composition of deep groundwater in sedimentary aquitards reveals a complex paleo-hydrological system affected by intensive tectonic activity. Water samples collected from deep research boreholes in the Golan Heights (Middle East) exhibit a unique combination of high salinity (>2,000 mg/L Cl) with low Na/Cl (<0.7) and Mg/Ca (<0.3) equivalent ratios, calcium chloride water type [Ca > (HCO3 + SO4)], relatively low δ18OVSMOW and δ2HVSMOW values (–7 and –42‰, respectively), and enriched 87Sr/86Sr ratios compared to the host rocks. The salinity source is related to ancient lagoonary hypersaline brines (10–5 Ma) that existed along the Dead Sea Rift (DSR). These brines intruded into the rocks surrounding the DSR and, based on the current study, also extended away from the rift. Following their subsurface intrusion, the brines have been gradually diluted by 18O- and 2H-depleted freshwater recharged at high elevations, nowadays leaving only traces of the brines that originally intruded. It is also shown that variable hydraulic conductivities in different formations control the dilution rates and subsequently the preservation of the entrapped brines. A paleo-hydrological reconstruction is provided to demonstrate intrusion and backflow dynamics and also the relationship to freshwater dilution, which was triggered by a tectonically active basin of the nearby continental DSR. Brines that initially migrated from the rift have since been gradually flushed back to the rift through the current natural outlets. As the system discharges, it mixes and converges with a separate hydrogeological system, while still preserving some of the geochemical signals of the ancient brines.
KW - Ca-chloride brines
KW - Deep groundwater
KW - Golan Heights
KW - Paleohydrology
KW - Saltwater-freshwater interactions
UR - http://www.scopus.com/inward/record.url?scp=85190786744&partnerID=8YFLogxK
U2 - 10.1007/s10040-024-02782-2
DO - 10.1007/s10040-024-02782-2
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AN - SCOPUS:85190786744
SN - 1431-2174
VL - 32
SP - 1101
EP - 1124
JO - Hydrogeology Journal
JF - Hydrogeology Journal
IS - 4
ER -