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[ABRIDGED] The purpose of this work is to evaluate how several elementsproduced by different nucleosynthesis processes behave with stellar age andprovide empirical relations to derive stellar ages from chemical abundances. Wederive different sets of ages using Gaia parallaxes for a sample of more than1000 FGK dwarf stars for which he have spectra from the HARPS-GTO program. Weanalyze the temporal evolution of different abundance ratios to find the bestchemical clocks. We find that [$\alpha$/Fe] ratio (average of Mg, Si and Ti),[O/Fe] and [Zn/Fe] are good age proxies with a lower dispersion than theage-metallicity dispersion. Several abundance ratios present a significantcorrelation with age for chemically separated thin disk stars (i.e.low-$\alpha$) but in the case of the chemically defined thick disk stars (i.e.high-$\alpha$) only the elements Mg, Si, Ca and TiII show a clear correlationwith age. We find that the thick disk stars are more enriched in light-selements than thin disk stars of similar age. The maximum enrichment ofs-process elements in the thin disk occurs in the youngest stars which in turnhave solar metallicity. The slopes of the [X/Fe]-age relations are quiteconstant for O, Mg, Si, Ti, Zn, Sr and Eu regardless of the metallicity.However, this is not the case for Al, Ca, Cu and most of the s-processelements, which display very different trends depending on the metallicity.This demonstrates the limitations of using simple linear relations based oncertain abundance ratios to obtain ages for stars of different metallicities.Finally, we show that by using 3D relations with a chemical clock and twostellar parameters (either Teff, [Fe/H] or stellar mass) we can explain up to89% of age variance in a star. A similar result is obtained when using 2Drelations with a chemical clock and one stellar parameter, being up to a 87% ofthe variance explained.

Abundance to age ratios in the HARPS-GTO sample with Gaia DR2: Chemical clocks for a range of [Fe/H]