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Science 12 July 1968:
Vol. 161. no. 3837, pp. 160 - 163
DOI: 10.1126/science.161.3837.160
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Articles

Gels Composed of Sodium-Aluminium Silicate, Lake Magadi, Kenya

Hans P. Eugster 1 and Blair F. Jones 2

1 Department of Geology, Johns Hopkins University, Baltimore, Maryland 21218
2 U. S. Geological Survey, Washington, D.C. 20242

Sodium-aluminum silicate gels are found in surficial deposits as thick as 5 centimeters in the Magadi area of Kenya. Chemical data indicate they are formed by the interaction of hot alkaline springwaters (67° to 82°C; pH, about 9) with alkali trachyte flows and their detritus, rather than by direct precipitation. In the process, Na2O is added from and silica is released to the saline waters of the springs. Algal mats protect the gels from erosion and act as thermal insulators. The gels are probably yearly accumulates that are washed into the lakes during floods. Crystallization of these gels in the laboratory yields analcite; this fact suggests that some analcite beds in lacustrine deposits may have formed from gels. Textural evidence indicates that cherts of rocks of the Pleistocene chert series in the Magadi area may have formed from soft sodium silicate gels. Similar gels may have acted as substrates for the accumulation and preservation of prebiological organic matter during the Precambrian.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Hydrotalcite and an Amorphous Clay Mineral in High-Magnesium Mudstones from the Kozani Basin, Greece.
(2000)
Journal of Sedimentary Research 70, 549-558
Lake Magadi, Kenya: a model for rift valley hydrochemistry and sedimentation?.
H. P. Eugster (1986)
Geological Society, London, Special Publications 25, 177-189
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