| Реферат: | eng: Variations in the contents of Fe and Mn and a number of trace elements (Co, Ni, Cu, Zn, As, Rb, Sr, Y, Zr, Pb, Th, U, Te, Ba, La, Ce, Nb, and Mo) were simultaneously measured in microlayers in samples of cobalt-rich ferromanganese crusts from the surface of three guyots of the Magellan Seamounts by means of synchrotron micro-XRF analysis on a VEPP-3 accelerator facility at the Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of Sciences. Micro-scale periodic variations were detected in the contents of most trace elements. The high and low contents of Co, Ni, and Mo in the crusts display also a larger scale periodicity. Based on the previous dating of ferromanganese crusts from the Magellan Seamounts and recent estimates of crust growth rates, we determined the geochronological position of maxima in the stratigraphic section and time intervals between trace element extrema. It was shown that micro-scale periodic variations in trace element contents in all the samples analyzed by us are similar despite the significant differences in the absolute contents of trace elements. The similar trace element variations suggest that this periodicity could be related to global changes in climatic conditions in the ocean. The analysis of correlations between trace elements and manganese, the major component of the crust, revealed the persistency of geochemical associations for all the age stages of crust formation. This can be considered as evidence for the hydrogenous origin of ferromanganese materials on the seamounts. Some specific variations in trace element contents observed in layer III were attributed to the contribution of volcanic processes during the respective stage of development.
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