Abstract
INVESTIGATING the many samples from 131 stations the author determines the distribution of the main types of marine deposits in the Arabian Sea. The new data confirm the essential facts given in Sir John Murray's latest chart. The transitional Globigerina ooze - red clay, however, is indicated separately on the new chart, as this mixed deposit is frequently difficult to assign to one or other of the component types. In several cases the distribution of the pelagic deposits is correlated with water movement, as in the Zanzibar Area. The Pteropod ooze in certain areas is shown to be correlated with the hydrographic conditions which cause a lack of oxygen and increased salinity resulting in a high death-rate in these molluscs. Special attention is given to the biological remains in all the samples as previous authors have worked mainly from the mineralogical and chemical point of view. The remains of organisms in the deposits have been separated out and the percentage remains of each of the common phyla determined. The total percentage of remains in the deposits is correlated with the depth, being high in shallow water, low in 500–600 metres, and then rising again in about 1,000 metres. This rise in the deep water is mainly due to the accumulation of Globigerina and other Foraminifera. Foraminifera are much the commonest constituents of these deposits, Globigerina being the chief genus which with other Foraminfera forms enormous areas of deep sea oozes. It is found that the green and brown muds have the largest foraminiferal fauna, and more than twice as many species occurred in the green mud deposits than in any other. In two instances only did any one species occur in great numbers—Rhabdammina abyssorum from a deposit of mud in the Gulf of Aden where the residue after washing consisted almost entirely of these shells, and Dendrophrya ramosa from a station in the Zanzibar area occurred in very, large numbers.
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Marine Deposits of the Arabian Sea*. Nature 144, 841 (1939). https://doi.org/10.1038/144841b0
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DOI: https://doi.org/10.1038/144841b0