Mineralogy and geochemistry of the pliocene iron-rich laterite in the Vatera area, Lesvos Island, Greece and its genesis
- 80 Downloads
A nickel laterite deposit occurs in the Vatera area of Lesvos Island, Greece, and is transgressively developed on serpentinized basic rock (norite). The overlying sedimentary rocks include marls and marly limestones with sandstone intercalations and belong to the Pliocene sediments. The following lateritic zones are defined from the bottom to top layers: a) bedrock (norite); b) serpentinized zone; c) goethitic zone. The bedrock consists of the following primary minerals: basic plagioclase, orthopyroxenes and clinopyroxenes. The serpentinized zone includes clinochrysotile, lizardite, antigorite clinoenstatite, calcite and dolomite while in the goethic zone there are goethite, quartz, pyrite, chromite, dolomite. A12O3, Fe2O3, CaO, Na2O, K2O, Ba, Sr, Ni, C and S are enriched in the goethitic zone. Nickel enrichment is related to the formation of nickeliferons minerals substituting for Mg or/and Fe in the goethite and pyrite. Enrichment of Ni in the matrix may be due to the presence of amorphous Ni-silicates (pimelite). There is a significant change (decrease) in the concentration of Ni from the top to bottom parts of the laterite formation, indicating that there was no tendency to migrate downwards (immature laterite). A second support of the immaturity of the Vatera laterite is the incomplete oxidation of ferrous iron to form ferric iron hydroxides.
Under tropical/subtropical conditions, which dominated from the end of Miocene to the Pliocene the norite rocks of the Vatera area altered in response to reaction with acid solutions enriched in CO2. Due to hydrolysis and oxidation of pyroxenes, Mg2+, P4SiO4 and Ni2+ were removed in the continental acid solutions.
Key words:mineralogy geochemistry laterite genesis Lesvos Island Greece
Unable to display preview. Download preview PDF.
- Chatzidimitriadis, E., 1971, The laterite deposit of the Profitis Ilias, Vatera, Lesvos Island, Greece [J]: Bulletin of the Greek Geological Society, v.8, n.l, p. 60–69.Google Scholar
- Hecht, J., 1971–1974, 1:50000, Geological map of Lesvos Island [Z]: IGME.Google Scholar
- Katsikatsos, G., D. Mataragas, G. Mirigos, and E. Triantaphyllis, 1982, Geological study of Lesvos Island [Z]: IGME, Internal Report, Athens, 92p.Google Scholar
- Kelepertsis, A., 1977, Geochemistry of high k-andesites from Polichnitos area (Lesvos Island, Greece) [J: Prakt. Acad. Athenon, v.52, p.499–511.Google Scholar
- Kelepertsis, A., 2000, Applied geochemistry [M]: University of Athens, 232p.Google Scholar
- McFarlane, M. J., 1983, Laterites, in J. Carman and M. Wockes, eds., AGID guide to mineral resources development [M]: AGID, p. 441–448.Google Scholar
- Mayland, B., 1983, Geochemistry of sedimentary ore deposits [M]: Springer-Verlag, New York-Heidelberg-Berlin, 305p.Google Scholar
- Prager, M., 1965, Geological sketch map of the volcanic areas, Lesvos Island [Z].Google Scholar
- Smirnov, V. L., 1976, Geology of mineral deposits [M]: Mir Publishers.Google Scholar
- Voreadis, G., 1957, The Fe-Ni deposits of Profitis Ilias area, Vatera, Lesvos Island, Greece [M]: IGME internal report.Google Scholar