Paleoclimate record in the Nubian Sandstone Aquifer,Sinai Peninsula,Egypt |
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| Authors: | Abdou Abouelmagd Mohamed Sultan Neil C Sturchio Farouk Soliman Mohamed Rashed Mohamed Ahmed Alan E Kehew Adam Milewski Kyle Chouinard |
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| Institution: | 1. Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008-5200, USA;2. Department of Geology, Suez Canal University, Ismailia, 41522, Egypt;3. Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, IL 60607-7059, USA;4. Department of Geology, University of Georgia, Athens, GA 30602, USA |
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| Abstract: | Sixteen groundwater samples collected from production wells tapping Lower Cretaceous Nubian Sandstone and fractured basement aquifers in Sinai were analyzed for their stable isotopic compositions, dissolved noble gas concentrations (recharge temperatures), tritium activities, and 14C abundances. Results define two groups of samples: Group I has older ages, lower recharge temperatures, and depleted isotopic compositions (adjusted 14C model age: 24,000–31,000 yr BP; δ18O: − 9.59‰ to − 6.53‰; δ2H: − 72.9‰ to − 42.9‰; < 1 TU; and recharge T: 17.5–22.0°C) compared to Group II (adjusted 14C model age: 700–4700 yr BP; δ18O: − 5.89‰ to − 4.84‰; δ2H: − 34.5‰ to − 24.1‰; < 1 to 2.78 TU; and recharge T: 20.6–26.2°C). Group II samples have isotopic compositions similar to those of average modern rainfall, with larger d-excess values than Group I waters, and locally measurable tritium activity (up to 2.8 TU). These observations are consistent with (1) the Nubian Aquifer being largely recharged prior to and/or during the Last Glacial Maximum (represented by Group I), possibly through the intensification of paleowesterlies; and (2) continued sporadic recharge during the relatively dry and warmer interglacial period (represented by Group II) under conditions similar to those of the present. |
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| Keywords: | Paleoclimate Nubian Sandstone Aquifer System (NSAS) Sinai Peninsula Noble gases 14C adjusted model age Paleowesterlies Paleomonsoon |
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