The sedimentology of the Dead Sea
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The Dead Sea, one of the most saline lakes in the world, has recently (1979) undergone a major change in its hydrologic regime resulting in the mixing of its once stable meromictis. Prior to, and during this change, a sedimentologic study was undertaken to document the types of sediments in the Dead Sea, covering the entire western half of the lake, to refine ideas on the formation of the evaporite sediments and to explain the distribution of sediments in the Dead Sea.
Study of the mineralogy and particle-size distribution of sediments of the Dead Sea reveals that, of the primary minerals, gypsum concentrates in the coarse silt and sand-size fractions whereas aragonite falls in the clay and fine silt fractions. The predominant sediment is a clayey silt.
The constituents of the bottom sediments fall into two groups: (1) particles of detrital or recycled rocks (limestone, quartz and clay minerals), and (2) crystals of minerals precipitated in surface waters (aragonite, gypsum, and halite).
Aragonite concentrations are low in bottom sediments of the northern Dead Sea and increase southward. Gypsum occurs in bottom sediments from all water depths. This distribution shows that the rate of sulfate reduction does not keep pace with the rate of sulfate precipitation. Halite was found in the southern part of the northern basin.
The areal distribution of primary minerals is a result of several processes. High concentrations reflect either periods of restricted circulation in certain areas, leading to massive precipitation, or high influx of saturated brines, leading to precipitation. By contrast, low concentrations reflect high input of detrital particles or periods of minor influx of highly saturated brine.
The lack of large concentrations of evaporite minerals reflects: (1) the abundant supply of detrital particles being carried into the Dead Sea that lower the relative contribution of evaporite minerals; (2) dilution of surface waters by fresh water, and (3) the low values of HCO3− and SO4= in Dead Sea waters.
KeywordsGypsum Bottom Sediment Halite Aragonite Evaporite
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- Amit, Ora, 1966, The behavior of clays in the Dead Sea: Unpubl. Masters Thesis, Hebrew University, 32 p. (in Hebrew)Google Scholar
- Begin, Z. B., Ehrlich, A., andNathan, Y., 1974, Lake Lisan, the Pleistocene precursor of the Dead Sea: Geol Survey of Israel Bull., v. 63, 30 pp.Google Scholar
- Beyth, M., 1977a, Recent evolution of Dead Sea brines: Geol. Survey Israel internal report MB/3/77, 11p.Google Scholar
- Beyth, M., 1977b, Present stage of Dead Sea brines: Geol. Survey Israel internal report MG/11/77, 5 p.Google Scholar
- Druckman, Y. andBeyth, M., 1977, “Salt reefs” a product of brine mixing, Lisan Straits, Dead Sea (a preliminary study): Geol. Survey of Israel report, MG/7/77, 15p.Google Scholar
- Friedman, G.M., 1964, Early diagenesis and lithification in carbonate sediments: Jour. Sedimentary Petrology, v. 34, p. 777–813.Google Scholar
- Friedman, G.M., 1965, On the origin of aragonite in the Dead Sea: Israel Jour. Earth-Sciences, v. 14, p. 79–85.Google Scholar
- Friedman, G.M., 1980, Review of depositional environments in evaporite deposits and the role of evaporites in hydrocarbon accumulation: Bull., Centres de Recherches Exploration-Production Elf-Aquitaine, v. 4, p. 589–608.Google Scholar
- Garber, R. A., 1980, The Sedimentology of the Dead Sea: unpubl. Ph.D. Thesis: Rensselaer Polytechnic Institute, Troy N.Y., 169p.Google Scholar
- Jackson, M. L., 1969, Soil Chemical Analysis-Advanced Course 2nd edition, 8th printing, 1973, Published by the author, Dept. of Soil Science, U. of Wisc., Madison, 895 p.Google Scholar
- Manspeizer, W., 1985, The Dead Sea Rift: impact of climate and tectonism on Pleistocene and Holocene sedimentation:in Biddle, K. T. an N. Christie-Blick (eds.), Strike-slip deformation, basin formation, and sedimentation: Soc. Econ. Paleontologists Mineralogists Spec. Publ. No. 37, p. 143–158.Google Scholar
- Millot, G., 1970, Geology of clays—weathering, sedimentology, geochemistry (trans. from French by W. R. Ferrand and Helene Paquet): New York and Berlin, Springer-Verlag, 429 p.Google Scholar
- Neev, D. andEmery, K.O., 1967, The Dead Sea, depositional processes and environments of evaporites: Geol. Survey Israel Bull., v. 41, 147 p.Google Scholar
- Neev, D., andHall, J.K., 1976, The Dead Sea Geophysical Survey, 19 July-1 August 1974: Geol. Survey Israel Internal Report MGD 6/76, 21 p.Google Scholar
- Schmalz, R. F., 1969, Deep-water evaporite deposition: A genetic model: Am Assoc. Petroleum Geol. Bull., v. 53, p. 798–823.Google Scholar
- Shepard, F. P., 1954, Nomenclature based on sand-silt-clay ratios: Jour. Sedimentary Pet., v. 24, p. 151–158.Google Scholar
- Starinsky, A., 1974, Relationship between Ca-chloride brines and sedimentary rocks in Israel: Unpubl. Ph.D. Thesis, Hebrew University, Jerusalem, 176p. (in Hebrew).Google Scholar
- Whitehouse, U. G., Jeffery, L. M., andDebbrecht, J.D., 1960, Differential settling tendencies of clay minerals in saline waters: Proc. Conf. Clays Clay Min., 7th, Washington, D. C., 1958, 5: p. 1–79.Google Scholar
- Yaffa, Shmuel, 1972, The Dead Sea climate: Meteorological Service of Israel, Publication No. 12, 8 p. (in Hebrew).Google Scholar