Terre rare e minerali pesanti nei paleoplacers della formazione di P.ta Serpeddì (Sardegna - Italia)

This paper describes the results of a detailed investigation carried out in six zones located in the Dolianova sector. These studies were carried out both on bulk samples and preconcentrate samples. Rutile, monazite, zircon and ilmenite, are the most important minerals of the placers. Apatite is a subordinate mineral, and garnets, tormaline, magnetite, micas, barite, pyrite, cromite, cassiterite are rarely found. Chemical characterization, by microprobe analyses, demonstrates that monazite is the most important REE-bearing mineral; it is concentrate in the magnetic classes between 0.5 e 1.3 testa (T). Low content of REE in the apatites also occurs. The rocks show total REE + Y content between 227 and 291 ppm, a moderate but constant fractionation ((La/Lu)n = 16) and a negative Eu anomaly (0.19< (Eu/Eu*)n <0.22).