Li abundances for 9 Turnoff ( TO ) stars of the intermediate metallicity cluster ( [ Fe/H ] =–1.4 ) NGC6752 are presented .
The cluster is known to show abundance anomalies and anticorrelations observed in both evolved and main sequence stars .
We find that Li abundance anticorrelates with Na ( and N ) and correlates with O in these Turn-Off stars .
For the first time we observe Pop II hot dwarfs systematically departing from the Spite plateau .
The observed anticorrelations are in qualitative agreement with what is expected if the original gas were contaminated by Intermediate Mass AGB - processed material .
However , a quantitative comparison shows that none of the existing models can reproduce all the observations at once .
The very large amount of processed gas present in the cluster does not imply a ’ pollution ’ , but rather that the whole protocluster cloud was enriched by a previous generation of stars .
We finally note that the different abundance patterns in NGC 6397 and NGC 6752 imply different ejecta of the preenrichment composition for the two clusters .