Arc magmas are more oxidized than mid-ocean ridge basalts; however, there is continuing debate as to whether this higher oxidation state is inherited from the source magma or developed during late-stage magmatic differentiation processes. Well-constrained Late Jurassic to Early Cretaceous arc-related intermediate to felsic rocks derived from distinct magma sources provide us with a good opportunity to resolve this enigma. A series of granitoids from the western Central Lhasa subterrane were analyzed for whole-rock magnetic susceptibility, Fe2O3/FeO ratios, and trace elements in zircon. Compared to Late Jurassic samples (1.8 +/- 2.0 x 10(-4) emu g(-1) oe(-1), Fe3+/Fe-total = 0.32 +/- 0.07, zircon Ce4+/Ce3+* = 15.0 +/- 13.4), Early Cretaceous rocks show higher whole-rock magnetic susceptibility (5.8 +/- 2.5 x 10(-4) emu g(-1) oe(-1)), Fe3+/Fe-total ratios (0.43 +/- 0.04), and zircon Ce4+/Ce3+* values (23.9 +/- 22.3). In addition, positive correlations among whole-rock magnetic susceptibility, Fe3+/Fe-total ratios, and zircon Ce4+/Ce3+* reveal a slight increase in oxidation state from fO(2) = QFM to NNO in the Late Jurassic to fO(2) = similar to NNO in the Early Cretaceous. Obvious linear correlation between oxidation indices (whole-rock magnetic susceptibility, zircon Ce4+/Ce3+*) and source signatures (zircon epsilon Hf(t), T-DM (C) ages) indicates that the oxidation state was predominantly inherited from the source with only a minor contribution from magmatic differentiation. Thus, the sources for both the Late Jurassic and Early Cretaceous rocks were probably influenced by mantle wedge-derived magma, contributing to the increased fO(2). Compared to ore-forming rocks at giant porphyry Cu deposits, the relatively low oxidation state (QFM to NNO) and negative epsilon Hf(t) (-16 to 0) of the studied granitoids implies relative infertility. However, this study demonstrates two potential fast and effective indices (fO(2) and epsilon Hf(t)) to evaluate the fertility of granitoids for porphyry-style mineralization. In an exploration context for the west Central Lhasa subterrane, features indicative of potential fertility might include more oxidized, positive epsilon Hf(t), young rocks (< 130 Ma).