XRD, INAA and Mössbauer characterisation of some antartic soil cores from Wood bay

Marine, lacustrine and terrestrial soil cores, sampled in a restricted area of Wood Bay in Antarctica, were characterised by X-ray diffraction, instrumental neutron activation analysis and 57Fe Móssbauer spectroscopy. The soils, formed from mechanical disgregation and weathering of rocks of volcanic origin from Mt. Melbourne, consist of alkaline feldspar, olivine, augitic clinopvroxene, and iron oxides such as haematite, goethite, and magnetite. Lacustrine and terrestrial soils are richer in clinopyroxene whereas marine soils are richer in olivine. This finding shows that the soils retain a content in olivine and clinopyroxene comparable to that found in the parent lava outcropping in the Mt. Melbourne volcano. The soils appeal' at the initial stage of weathering. Two main weathering effects are observed: 1) atmospheric oxygen determines the oxidation of the iron(Il) present in olivine and clinopyroxene and the neo-formed iron(III) is mainly retained in silicate sites as structural iron(lll). 2) A part of magnetite, present as a primary constituent of the volcanic rocks, is oxidised to bulk haematite and goethite