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GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L05503, doi:10.1029/2003GL019234, 2004

One million year old groundwater in the Sahara revealed by krypton-81 and chlorine-36

N. C. Sturchio

Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, Illinois, USA


X. Du

Physics Division, Argonne National Laboratory, Argonne, Illinois, USA
Physics Department, Northwestern University, Evanston, Illinois, USA


R. Purtschert

Institute of Physics, University of Bern, Bern, Switzerland


B. E. Lehmann

Institute of Physics, University of Bern, Bern, Switzerland


M. Sultan

Department of Geology, State University of New York at Buffalo, Buffalo, New York, USA


L. J. Patterson

Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, Illinois, USA


Z.-T. Lu

Physics Division, Argonne National Laboratory, Argonne, Illinois, USA


P. Müller

Physics Division, Argonne National Laboratory, Argonne, Illinois, USA


T. Bigler

Institute of Physics, University of Bern, Bern, Switzerland


K. Bailey

Physics Division, Argonne National Laboratory, Argonne, Illinois, USA


T. P. O'Connor

Physics Division, Argonne National Laboratory, Argonne, Illinois, USA


L. Young

Chemistry Division, Argonne National Laboratory, Argonne, Illinois, USA


R. Lorenzo

Institute of Physics, University of Bern, Bern, Switzerland


R. Becker

Department of Geology, State University of New York at Buffalo, Buffalo, New York, USA


Z. El Alfy

Egyptian Geological Survey and Mining Authority, Cairo, Egypt


B. El Kaliouby

Department of Geology, Ain Shams University, Cairo, Egypt


Y. Dawood

Department of Geology, Ain Shams University, Cairo, Egypt


A. M. A. Abdallah

Department of Geology, Ain Shams University, Cairo, Egypt


Abstract

Measurements of 81Kr/Kr in deep groundwater from the Nubian Aquifer (Egypt) were performed by a new laser-based atom-counting method. 81Kr ages range from ∼2 × 105 to ∼1 × 106 yr, correlate with 36Cl/Cl ratios, and are consistent with lateral flow of groundwater from a recharge area near the Uweinat Uplift in SW Egypt. Low δ2H values of the 81Kr-dated groundwater reveal a recurrent Atlantic moisture source during Pleistocene pluvial periods. These results indicate that the 81Kr method for dating old groundwater is robust and such measurements can now be applied to a wide range of hydrologic problems.

Received 8 December 2003; accepted 12 February 2004; published 12 March 2004.

Index Terms: 1035 Geochemistry: Geochronology; 1832 Hydrology: Groundwater transport; 9820 General or Miscellaneous: Techniques applicable in three or more fields.


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Citation: Sturchio, N. C., et al. (2004), One million year old groundwater in the Sahara revealed by krypton-81 and chlorine-36, Geophys. Res. Lett., 31, L05503, doi:10.1029/2003GL019234.