OSADY EUPELAGICZNE JAKO POTENCJALNE ŹRÓDŁO POZYSKIWANIA PIERWIASTKÓW ZIEM RZADKICH

Abstract

EUPELAGIC SEDIMENTS AS A POTENTIAL RESOURCE FOR RARE EARTH ELEMENTSAbstract. The study deals with the potential and suitability of selected eupelagic sediments (siliceous-clayey silts) and hydrogenic marine ferromanganese oxides (polymetallic nodules and cobalt-rich manganese crust) as a possible resource of rare earth elements (REE). A total of 137 surface sediment samples from the Interoceanmetal Joint Organization (IOM) H11 Fe-Mn nodule deposit, eastern part of the Clarion-Clipperton nodule field (located the Clarion-Clipperton Fracture Zone – CCFZ; tropical Pacific), were collected using a box corer during a research cruise of the R/V Yuzhmorgeologiya. The chemical composition of samples was analysed after 4-acid digestion by inductively coupled plasma mass spectrometry (ICP-MS) and compared with available literature data of REE concentration in marine ferromanganese oxides and eupelagic sediments from the prospective ocean areas. The geochemical analysis shows the total rare earth elements and yttrium (ΣREY) contents in the investigated samples range from 199.99 ppm to 616.56 ppm with an average of 288.81 ppm. Comparative study of average REY concentration in polymetallic nodules and cobalt-rich manganese crust from selected areas of the global ocean reveals the highest content of REY in cobalt-rich manganese crust of the Indian Ocean, Pacific Crust Zone (PCZ – the area of seamounts in the central and western equatorial Pacific, from the equator area to 20°N latitude) and Northern Pacific (non – PCZ). Polymetallic nodules are characterized by intermediate concentration of REY, and the variations of composition depend on genetic types of nodules.