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We present deep (9 hours) Gemini-N/GNIRS near-infrared spectroscopicobservations of ULAS J1342+0928, a luminous quasar at z=7.54. Various broademission lines were detected, as well as the underlying continuum and ironforests over the rest-frame wavelength 970-2930A. There is a clear trend thathigher-ionization emission lines show larger blueshifts with CIV1549 exhibiting5510^{+240}_{-110} km s-1 blueshift with respect to the systematic redshiftfrom the far-infrared [CII] 158um emission line. Those high ionization lineshave wide profiles with FWHM more than 10000 km s-1. A modest blueshift of340^{+110}_{-80} km s-1 is also seen in MgII, the lowest ionization lineidentified in the spectrum. The updated MgII-based black hole mass ofM_BH=9.1_{-1.3}^{+1.4} x 10^8 M_sun and the Eddington ratio ofL_bol/L_Edd=1.1_{-0.2}^{+0.2} confirm that ULAS J1342+0928 is powered by amassive and actively accreting black hole. There is no significant differencein the emission line ratios such as SiIV/CIV and AlIII/CIV when compared tolower-redshift quasars in a similar luminosity range, which suggests earlymetal pollution of the broad-line-region clouds. This trend also holds for theFeII/MgII line ratio, known as a cosmic clock that traces the iron enrichmentin the early universe. Different iron templates and continuum fitting rangeswere used to explore how the FeII/MgII measurement changes as a function ofspectral modeling. Quasars at even higher redshift or at fainter luminosityrange (L_bol<10^46 erg s-1) are needed to probe the sites of early metalenrichment and a corresponding change in the FeII/MgII ratio.

No Redshift Evolution in the Broad Line Region Metallicity up to z=7.54: Deep NIR Spectroscopy of ULAS J1342+0928