Quantitative Analysis of Valences for Manganese in Cobalt-rich Crust Samples from the Central Pacific Ocean by X-ray Fluorescence Spectrometry

The Kβspectral peak parameters of the mixed samples with different ratios of MnO and MnO2 were studied using a conventional X-ray fluorescence spectrometer and PeakFit spectral processing software. The measured spectra were decomposed into various single spectral peak parameters such as peak position, peak intensity and FWHM etc. by deconvolution of overlapped spectral peaks. The relationship between the peak parameters and the contents of different Mn valences was studied. According to the results, the relative contents of the Mn4+ in a large number of cobaltrich crust samples from the central Pacific seamount area were quantified with the range of 80%~100%. It summarized a law that the content of Mn4+ is high in cobaltrich crusts′ outer layer and middle layer, but low in cobalt rich crusts′ inner layer. It is thus proposed that the changes of Mn4+ content in cobalt rich crusts could be the result of Antarctic bottom water activity since the Quaternary period.