Hostname: page-component-848d4c4894-xm8r8 Total loading time: 0 Render date: 2024-06-21T19:37:20.826Z Has data issue: false hasContentIssue false
  • English
  • Français

Timing and intensity of groundwater movement during Egyptian Sahara pluvial periods by U-series analysis of secondary U in ores and carbonates

Published online by Cambridge University Press:  20 January 2017

J.K. Osmond  and
Adel A. Dabous
Get access Rights & Permissions [Opens in a new window]

Abstract

Wet climatic episodes are known to have prevailed in the Egyptian Sahara several times during the late Quaternary, most recently during the Holocene 8000 yr ago. Earlier wet episodes have been recognized as having occurred during the past 300,000 yr and have been dated by U-series methods in speleothems and in lake travertines. We show here that the times of enhanced groundwater movement can also be determined by 230Th/234U dating of secondary U in ores of uranium, iron, and phosphate. We also present evidence that such acceleration of groundwater movements is indicated by relatively low 234U/238U activity ratios in the secondary uranium. Our new data show that pluvial periods in Egypt occurred during marine oxygen isotope stages 4, 5, 6, and 7 and therefore are consistent with the view that the wet episodes are the results of migration of the tropical monsoonal belt driven primarily by the 23,000-yr precession cycle of the Milankovich curve, modulated by the 100,000-yr eccentricity cycle.

Keywords

GroundwaterPluvialUraniumU-seriesEgyptSaharaSpeleothemsIron orePhosphorite
Type
Research Article
Information
Quaternary Research , Volume 61 , Issue 1 , January 2004 , pp. 85 - 94
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Ayalon, A., Bar-Matthews, M., Kaufman, A., (2002). Climatic conditions during marine oxygen isotope stage 6 in the eastern Mediterranean region from the isotopic composition of speleothems of Soreq Cave, Israel. Geology. 30, 303–306.2.0.CO;2>CrossRefGoogle Scholar
Bar-Matthews, M., Ayalon, A., Kaufman, A., (2000). Timing and hydrological conditions of sapropel events in the Eastern Mediterranean, as evident from speleothems, Soreq Cave, Israel. Chemical Geology. 169, 145–156.Google Scholar
Brook, G., Embabi, N.S., Ashour, M.M., Edwards, R.L., Cheng, H., Cowart, J.B., Dabous, A.A., (2002). Djara cave in the Western Desert of Egypt: morphology and evidence of Quaternary climatic change. Cave and Karst Science. 29, 57–66.Google Scholar
Brook, G., Embabi, N.S., Ashour, M.M., Edwards, R.L., Cheng, H., Cowart, J.B., Dabous, A.A., (2003). Quaternary environmental change in the Western Desert of Egypt: evidence from cave speleothems, spring tufas and playa sediments. Zeitschrift fur Geomorphologie N.F. Suppl.. 131, 59–87.Google Scholar
Burns, S.J., Fleitman, D., Matter, A., Neff, U., Mangini, A., (2001). Speleothem evidence from Oman for continental pluvial events during interglacial periods. Geology. 29, 623–626.Google Scholar
Crombie, M.K., Arvidson, R.E., Sturchio, N.C., El Alfy, Z., Abu Zeid, K., (1997). Age and isotopic constraints on Pleistocene pluvial episodes in the Western Desert, Egypt. Palaeogeography, Palaeoclimatology, Palaeoecology. 130, 337–355.Google Scholar
Dabous, A.A., (1994). The geochemistry of uranium and thorium isotopes in the Western Desert of Egypt. Geochimica et Cosmochimica Acta. 58, 4591–4600.Google Scholar
Dabous, A.A., (2002). Uranium isotopic evidence for the origin of the Bahariya iron deposits of Egypt. Ore Geology Reviews. 19, 165–186.Google Scholar
Dabous, A.A., (2003). Secondary uranium in phosphorites and associated groundwater in Egypt. Geochemical Journal. 37, 413–426.Google Scholar
Dabous, A.A., Osmond, J.K., (2000). U/Th isotopic study of speleothems from the Wadi Sannur Cavern, Eastern Desert of Egypt. Carbonates and Evaporites. 15, 1–6.Google Scholar
Dabous, A.A., Osmond, J.K., (2001). Uranium isotopic study of artesian and pluvial contributions to the Nubian Aquifer, Western Desert, Egypt. Journal of Hydrology. 243, 242–253.Google Scholar
Dabous, A.A., Osmond, J.K., Dawood, Y.H., (2002). Uranium/thorium isotope evidence for ground water history in the Eastern Desert of Egypt. Journal of Arid Environments. 50, 343–357.Google Scholar
Fontugne, M., Arnold, M., Labeyrie, L., Paterne, M., Calvert, S., Duplessy, J.-C., (1994). Paleoenvironment, sapropel chronology and Nile River discharge during the last 20,000 years as indicated by deep-sea sediment records in the Eastern Mediterranean. Bar-Yosef, O., Kra, R.S., Late Quaternary and Paleoclimates of the Eastern Mediterranean, Radiocarbon. 75–88.Google Scholar
Henning, G.H., Grun, R., Brunnacker, K., (1983). Speleothems, travertines, and paleoclimates. Quaternary Research. 20, 1–29.CrossRefGoogle Scholar
Jenkins, J.A., Williams, D.F., (1983). Nile water as a cause of Eastern Mediterranean sapropel formation: evidence for and against. Geophysical Research. 9, 521–534.Google Scholar
Kaufman, A., Broeker, W.S., (1965). Comparison of 230Th and 14C ages for carbonate materials from Lake Lahontan and Bonneville. Journal of Geophysical. Research. 70, 4039–4054.CrossRefGoogle Scholar
Kaufman, A., Wasserburg, G.J., Porcelli, D., Bar-Matthews, M., Ayalon, A., Halicz, L., (1998). U–Th isotope systematics from the Soreq Cave, Israel and climatic correlations. Earth and Planetary Science Letters. 156, 141–155.CrossRefGoogle Scholar
Kutzbach, J.E., (1981). Monsoon climate of the Early Holocene: climate experiment with Earth's orbital parameters for 9000 years ago. Science. 214, 59–61.Google Scholar
Lally, A.E., (1992). Chemical procedures. Ivanovich, M., Harmon, R.S., Uranium Series Disequilibrium: Application to Environmental Problems. 2nd ed. Oxford Univ. Press, Oxford., 95–126.Google Scholar
Livnat, A., Kronfeld, J., (1985). Paleoclimatic implications of U-series dates for lake sediments and travertines in the Arava Rift Valley, Israel. Quaternary Research. 24, 164–172.CrossRefGoogle Scholar
Ludwig, K.R., Titterington, D.M., (1994). Calculations of 230Th/234U isochrons, ages, and errors. Geochimica Cosmochimica Acta. 58, 5031–5042.CrossRefGoogle Scholar
Martinson, D.G., Pisias, N.G., Hays, J.D., Imbrie, J., Moore, T.C. Jr., Shackleton, N.J., (1987). Age dating and the orbital theory of the ice ages: development of a high-resolution 0 to 300,000-year chronostratigraphy. Quaternary Research. 27, 1–29.Google Scholar
Melieres, M.-A., Rossignol-Strick, M., Malaize, B., (1997). Relation between low latitude insolation and δ18O change of atmospheric oxygen for the last 200 kyrs, as revealed by Mediterranean sapropels. Geophysical Research Letters. 24, 1235–1238.CrossRefGoogle Scholar
Osmond, J.K., Cowart, J.B., (2000). U-series nuclides as tracers in groundwater hydrology. Cook, P., Herczeg, A., Environmental Tracers in Subsurface Hydrology. Kluwer, Boston., 145–174.Google Scholar
Osmond, J.K., Dabous, A.A., Dawood, Y.H., (1999). U series age and origin of two secondary uranium deposits, central Eastern Desert, Egypt. Economic Geology. 94, 273–280.Google Scholar
Prell, W.L., Kutzbach, J.E., (1987). Monsoon variability over the past 150,000 years. Journal of Geophysical Research. 92, 8411–8425.Google Scholar
Railsback, L.B., Dabous, A.A., Osmond, J.K., Fleisher, C.J., (2002). Petrographic and geochemical screening of speleothems for U-series dating: an example from recrystallized stalagmites from Wadi Sannur Cavern, Egypt. Journal of Cave and Karst Studies. 64, 108–116.Google Scholar
Rossignol-Strick, M., (1983). African monsoons, an immediate climate response to orbital insolation. Nature. 304, 46–49.Google Scholar
Rossignol-Strick, M., Nesteroff, W., Olive, P., Vergnaud-Grazzini, C., (1982). After the deluge: Mediterranean stagnation and sapropel formation. Nature. 295, 105–110.Google Scholar
Rossignol-Strick, M., Paterne, M., (1999). A synthetic pollen record of the Eastern Mediterranean sapropels of the last 1 Ma: implications for the time-scale and formation of sapropels. Marine Geology. 153, 221–237.CrossRefGoogle Scholar
Ruddiman, W.F., (2001). Earth's Climate: Past and Future. Freeman, New York.Google Scholar
Said, R., (1990). Quaternary. Said, R., The Geology of Egypt. Balkema, Rotterdam., 499–503.Google Scholar
Shackleton, N.J., Opdyke, N.D., (1973). Oxygen isotope and paleomagnetic stratigraphy of equatorial Pacific core V28-238: oxygen isotope temperatures and ice volumes of a 105 and 106 year scale. Quaternary Research. 3, 39–55.CrossRefGoogle Scholar
Szabo, B.J., Haynes, C.V., Maxwell, T.A., (1995). Ages of Quaternary pluvial episodes determined by uranium-series and radiocarbon dating of lacustrine deposits of Eastern Sahara. Palaeogeography, Palaeoclimatology, Palaeoecology. 113, 227–242.CrossRefGoogle Scholar
Thorweihe, U., (1990). Nubian aquifer system. Said, R., Geology of Egypt. Balkema, Rotterdam., 601–611.Google Scholar
Williams, D.F., Thunell, R.C., Kennett, J.P., (1978). Periodic freshwater flooding and stagnation of the Eastern Mediterranean Sea during the Late Quaternary. Science. 201, 252–254.CrossRefGoogle ScholarPubMed