OXYGEN ISOTOPIC COMPOSITION OF OPALINE PHYTOLITHS - POTENTIAL FOR TERRESTRIAL CLIMATIC RECONSTRUCTION

Opaline mineralized bodies are produced by many terrestrial plants and accumulate in certain soils and archaeological sites. Analyses of the oxygen isotopic compositions of these so-called phytoliths from stems and leaves of wheat plants grown in a greenhouse showed a linear rela tionship with stem and leaf water isotopic compositions and hence, ind irectly, rain water isotopic composition. Analyses of wheat plants gro wn in fields showed that stem phytoliths isotopic composition directly reflects the seasonal air temperature change, whereas leaf phytoliths isotopic composition reflects both temperature and relative humidity. Temperature and the oxygen isotopic composition of stem phytoliths we re related by an equation similar to that proposed for marine opal. Ox ygen isotopic compositions of fossil phytoliths, and in particular tho se from stems, could be valuable for reconstructing past terrestrial c limate change.