Ca II triplet spectroscopy has been used to derive stellar metallicities for individual stars in four LMC fields situated at galactocentric distances of 3° , 5° , 6° and 8° to the north of the Bar .
Observed metallicity distributions show a well defined peak , with a tail toward low metallicities .
The mean metallicity remains constant until 6° ( [ Fe/H ] \sim -0.5 dex ) , while for the outermost field , at 8° , the mean metallicity is substantially lower than in the rest of the disk ( [ Fe/H ] \sim -0.8 dex ) .
The combination of spectroscopy with deep CCD photometry has allowed us to break the RGB age–metallicity degeneracy and compute the ages for the objects observed spectroscopically .
The obtained age–metallicity relationships for our four fields are statistically indistinguishable .
We conclude that the lower mean metallicity in the outermost field is a consequence of it having a lower fraction of intermediate-age stars , which are more metal-rich than the older stars .
The disk age–metallicity relationship is similar to that for clusters .
However , the lack of objects with ages between 3 and 10 Gyr is not observed in the field population .
Finally , we used data from the literature to derive consistently the age–metallicity relationship of the bar .
Simple chemical evolution models have been used to reproduce the observed age–metallicity relationships with the purpose of investigating which mechanism has participated in the evolution of the disk and bar .
We find that while the disk age–metallicity relationship is well reproduced by close-box models or models with a small degree of outflow , that of the bar is only reproduced by models with combination of infall and outflow .