The Mazaertag layered intrusion is located in the northwestern part of the Tarim large igneous province where several early Permian layered ma?c-ultrama?c intrusions host important Fe-Ti oxide deposits. The intrusion covers an area of ~0.13 km2 and has a vertical stratigraphic thickness of at least 300 m. It consists chie?y of olivine clinopyroxenite, and is cut through by the nearby mafic-ultramafic dykes. In this paper, we report new mineral chemistry data and whole-rock chemical and isotopic compositions for the Mazaertag intrusion along with whole-rock isotopic compositions for the nearby mafic dykes. The averaged compositions of cumulus olivine, clinopyroxene and intercumulus plagioclase within individual samples range from Fo71?73, Mg# = 76 to 79 and An65?75 but they do not define sustained reversals. The observed mineral compositions are consistent with the differentiation of a single batch of magma in a closed system. Rocks of the Mazaertag intrusion are characterized by enrichment in light REE relative to heavy REE, positive Nb and Ta anomalies and a small range of age-corrected εNd(t) (?0.1 to +0.9) and initial 87Sr/86Sr values (0.7044 to 0.7068). The slightly lower εNd(t), initial 206Pb/204Pb and higher initial 87Sr/86Sr values of the intrusion compared to those of the least contaminated dykes [εNd(t) = +2.8 to +3.4; (206Pb/204Pb)i = 18.516?18.521; (87Sr/86Sr)i = 0.7038?0.7041] imply that the Mazaertag magma was subjected to small to modest degrees of contamination by the upper crust. The Sr-Nd isotopic compositions of the least contaminated dykes are consistent with derivation from a FOZO-like mantle source. The parental magma of the Mazaertag intrusion, estimated from clinopyroxene compositions using mineral-melt partition coef?cients, has trace element compositions similar to some of the most primitive mafic dykes in the same area. This suggests that the Mazaertag intrusion and mafic dykes shared a similar mantle source. Therefore, the parental magma of the Mazaertag intrusion was interpreted to have originated from a mantle plume. Based on the Cr2O3 contents in titanomagnetite and less-evolved characteristics of the Mazaertag intrusion compared to the Wajilitag Fe-Ti oxide deposit in Bachu, it is speculated that there might not be a potential to ?nd economic Fe-Ti oxide mineralization in the intrusion.