954 resultados para Elevation of event
Resumo:
The first data on chemical composition of nonreef-building non-zooxanthellate deep-sea corals presented in this publication allow us to identify following tendencies manifested in the biomineralization process. Comparison of concentration levels of some chemical elements in scleractinian corals and ambient ocean waters suggests that corals do not accumulate K in the process of biomineralization and weakly accumulate Mg, whereas Ca, Sr, Si, Al, Ti, Mn, Zn, Cu, Cd, Pb, and Fe are concentrated in skeletons of corals with enrichment coefficients of 10**3 to 10**7. Correlations between components contained in the skeletons of scleractinian corals suggest that the source of Al, Si, Fe, and Ti in them is the clayey constituent of bottom sediments and zooplankton, while trace elements are likely accumulated via bioassimilation from seawater. Such elements as Mn, Sr, Pb, and Cd can structurally substitute Ca in calcite and aragonite. Variations in concentrations of the elements in coral skeletons depending on their habitat depths are fairly significant. As could be expected Ca and Mg concentrations are prone to decrease with depth (R = -0.55 and -0.51, respectively), which can possibly be caused by partial dissolution of carbonate skeletons with increasing depth, whereas the Sr/Ca ratio does not depend on depth.
Resumo:
Composition and distribution.of ice-rafted coarse debris from the Kara Sea bottom were investigated. This material was obtained on 42 stations in Cruise 49 of R/V Dmitry Mendeleev by Sigsby trawls, box corers, grabs, and gravity corers. Existence of two main petrographic provinces is suggested: (1) West Kara and (2) East Kara. They differ in composition and sources of debris material. It is supposed that debris was transported mainly by floating ice. In Upper Pleistocene time rafting by glaciers and icebergs was also very possible.
