Title:

Distribution of minor elements in cores from the Southwest Africa shelf with notes on plankton and fish mortality

Publication Year:
1980
Abstract:

Twenty-seven minor and a few major elements were analyzed in a grab sample from the Walvis Bay and in cores of organic-rich green muds and terrigenous sediments from the Southwest Africa shelf. The green muds are locally enriched in Ba, Br, Cd, Mo, Se and U. The high Ba concentrations will be due to abundance of certain diatoms. Mo concentrations are high in cores poor in Fe and Mn; hardly any Mo occurs in an ironrich core, arguing against co-precipitation. Zn values are relatively low, except for 344 ppm in a sample with 8% Ba. High values of Fe and other elements in some core-top samples argue for not-strictly anoxic conditions at the sediment—water interface. The vertical distribution of Ba, Ca and Sr suggests less intense upwelling in the past, the process becoming more vigorous about 2000 years ago. Samples of phosphatized muds are enriched in As, Br, La, Sr, U, and depleted in Ce and other elements. Phosphatized muds and unconsolidated phosphorites detected by different expeditions are located in a nearshore area characterized by high phytoplankton productivity and the occurrence of strong seasonal thermoclines.

Publication Title:

Marine Geology

Volume:
37
Issue:
1-2
Pages:
91-132
Item Type:
Journal Article
Language:
en

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