Context : Chemical element abundances for distant Galactic globular clusters ( GCs ) hold important clues to the origin of the Milky Way halo and its substructures .

Aims : We study the chemical composition of red giant stars in Pal 4 — one of the most remote GCs in the Milky Way — and compare our abundance measurements to those for both low surface brightness dwarf galaxies , and GCs in the inner and the outer halo .

Methods : By co-adding high-resolution , low-S/N Keck/HIRES spectra of 19 stars along the red giant branch , we estimate chemical abundance ratios of 20 \alpha - , iron peak- , and neutron-capture elements .
Our method gives total uncertainties on most element-to-iron ratios of typically 0.2 dex .

Results : We measure { [ Fe / H ] } = -1.41 \pm 0.04 ~ { } { ( statistical ) } \pm 0.17 ~ { } { ( systematic ) } and an \alpha -enhancement of [ \alpha /Fe ] = +0.38 \pm 0.11 dex , which is consistent with the canonical value of \sim +0.4 dex found for Galactic halo field stars and most halo GCs at this metallicity .
Although Pal 4 has higher enhancements in the heavier elements with respect to the halo , the majority of the element ratios are , within the measurement errors , consistent with those for local halo field stars .
We find , however , evidence for a lower [ Mg/Ca ] ratio than in other halo clusters .

Conclusions : Based on the available evidence , we conclude that the material from which Pal 4 and the Galactic halo formed experienced similar enrichment processes , despite the apparently younger age of this cluster .
Within the limitations of our methodology we find no significant indication of an iron spread , as is typical of genuine GCs of the Milky Way .
However , abundance ratios for individual stars in Pal 4 and other distant satellites are urgently needed to understand the relationship , if any , between remote GCs and other halo substructures ( i.e. , luminous and ultra-faint dwarf spheroidal galaxies ) .