Distribution of various components in a hydrogeneous ferromanganese nodule and an Afanasiy Nikitin Seamount crust from Indian Ocean - A geochemical study using micro-PIXE

The present study emphasizes the geochemical features pertaining to the distribution of the major and minor elements in a hydrogenous ferromanganese, nodule and a seamount crust originating from the Indian Ocean. The micro-PIXE elemental maps indicate the successive layer formation of Fe and Mn in these deposits. A Ni association with Mn has been further confirmed by observing a Ni-Mn spatial correlation together with their compositional correlation. In addition, the core or the nucleus of the ferromanganese nodule was found to be rich in Fe and not Mn, which strengthens the assumptions made earlier that the nodule formation started with Fe deposition which catalysed the growth of a ferromanganese nodule or crust by successive deposition of Mn and Fe. Irregular patterns of Mn and Fe layers were observed and discussed. Instead of the more often studied Co-Fe association in nodules and crusts, the intra nodule microanalysis revealed a Co-Mn correlation that will be discussed in this paper. (C) 2001 Elsevier Science B.V. All rights reserved.