engleski

Distribution of rare earth elements in different grain-size fractions of terra rossa soils in Istria, Croatia

Distribution of REE was studied in different grain-size fractions of six terra rossa soil samples from Istria, Croatia. Although the total REE content of the <2 mm fraction of different terra rossa samples is quite variable (it ranges from 104.09 to 394.95 ppm), the chondrite-normalized REE distributions show similar patterns to those of ES. No relation was observed between the REE content and clay mineralogy in analysed terra rossa samples. The total REE content of the <2 mm fraction of different terra rossa ranges from 123.44 to 211.14 ppm. This fraction is not the main carrier of the REE. Total REE are 20 to 140% higher in the 2-45 mm fraction than in the <2 mm fraction. *LREE/*HREE ratios are significantly higher in the 2-45 mm and 45-200 mm fractions than in the <2 mm fraction. Significant positive Ce-anomaly was observed in the 2-45 mm fraction and especially in the 45-200 mm fraction of four terra rossa samples. The <2 mm fraction of those samples does not bear this imprint. A wide range of total REE contents in bulk samples, the difference in *LREE/*HREE ratios in different grain size fractions and observed significant positive Ce-anomaly are in favour of polygenetic origin of terra rossa in Istria. The difference in REE distribution can be attributed to the REE content of both parent carbonate rocks and different external materials which have contributed in the genesis of terra rossa (loess, flysch, bauxite), modified by weathering processes which characterise specific pedoenvironment in which terra rossa is formed.

terra rossa; REE; Istria; Croatia

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