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High-resolution optical spectra of 30 metal-poor stars selected from the\Pristine\ survey are presented, based on observations taken with the GeminiObservatory GRACES spectrograph. Stellar parameters \teff and \logg aredetermined using a Gaia DR2 colour-temperature calibration and surface gravityfrom the Stefan-Boltzmann equation. GRACES spectra are used to determinechemical abundances (or upper-limits) for 20 elements (Li, O, Na, Mg, K, Ca,Ti, Sc, Cr, Mn, Fe, Ni, Cu, Zn, Y, Zr, Ba, La, Nd, Eu). These stars areconfirmed to be metal-poor ([Fe/H]$<-2.5$), with higher precision than fromearlier medium-resolution analyses. The chemistry for most targets is similarto other extremely metal-poor stars in the Galactic halo. Three stars near[Fe/H]$=-3.0$ have unusually low Ca and high Mg, suggestive of contributionsfrom few SN~II where alpha-element formation through hydrostaticnucleosynthesis was more efficient. Three new carbon-enhanced metal-poor starsare also identified (two CEMP-s and one potential CEMP-no star) when ourchemical abundances are combined with carbon from previous medium-resolutionanalyses. The GRACES spectra also provide precision radial velocities($\sigma_{\rm RV}\le0.2$km\,s$^{-1}$) for dynamical orbit calculations with theGaia DR2 proper motions. Most of our targets are dynamically associated withthe Galactic halo; however, five stars with [Fe/H]$<-3$ have planar-likeorbits, including one retrograde star. Another five stars are dynamicallyconsistent with the Gaia-Sequoia accretion event; three have typical halo[$\alpha$/Fe] ratios for their metallicities, whereas two are[Mg/Fe]-deficient, and one is a new CEMP-s candidate. These results arediscussed in terms of the formation and early chemical evolution of the Galaxy.

The Pristine survey -- XII: Gemini-GRACES chemo-dynamical study of newly discovered extremely metal-poor stars in the Galaxy