Abstract

In 1938, a dredging from the sea floor off California recovered about 6 kilograms of tubular, sub-spherical, flat, and irregular shaped barite concretions embedded in marine mud. These are poorly sorted in weight and size. They range from 1 to 25 centimeters in length. The physical, chemical, and mineralogical characteristics of the nodules are described and compared with those of other barite concretions found on land or dredged from the sea floor. Barium sulphate is present in amounts up to 77 per cent, in the form of small radial aggregates often within the tests of Pliocene Foraminifera.

Various theories of the origin of barite concretions are discussed and tested in terms of those characteristics which seem to be of genetic importance. It is believed that the most probable mode of origin was the interaction of interstitial sulphate-rich sea water of the sediment with ascending magmatic waters containing dissolved barium and strontium. Various bits of evidence suggest that the two other reported occurrences of barite concretions on the sea floor had a similar origin.

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