Mantle-derived rocks in large igneous provinces yield large variations in their chemical and isotopic compositions as well as redox conditions; however, the origin of these heterogeneities remains unclear. We present new geochemical and Sr–Nd–Hf–O isotopic data for the Hongge mafic–ultramafic intrusion and associated syenite in the Emeishan large igneous province (ELIP), and combine them with previously published data from coeval intrusive and volcanic rocks in the ELIP, to constrain the generation of the ELIP and associated world-class Fe–Ti–V oxide deposits. The rocks from the marginal zone of the Hongge intrusion have high-Ti basaltic-like compositions with high initial ⁸⁷Sr/⁸⁶Sr ratios (0.7084–0.7096) and unradiogenic ε_Nd (−7.7 to −5.9) and ε_Hf (−6.0 to −2.4) values, and represent the most enriched endmember of the high-Ti basaltic series observed in the ELIP to date. The marginal zone rocks, temporally and spatially associated basalts, and syenites yield depleted Zr and Hf contents with Zr/Sm (7.1–38.3) and Hf/Nd (0.05–0.12) ratios between those of marine sediment and OIB. The NdHf isotopic compositions of the marginal zone rocks plot above the terrestrial array, suggesting decoupling between Nd and Hf isotopic compositions. Mixing between subducted oceanic crusts, marine sediments and mantle peridotite accounts for the enriched SrNd isotopic compositions, ZrHf depletion, and the decoupling between Nd and Hf isotopic compositions in these samples as well as in other mafic–felsic intrusions of the ELIP. Zircon grains from the syenites yield more radiogenic ε_Hf values (+3.7 − +6.6) than the marginal zone rocks and have δ¹⁸O values of 3.9–5.7‰, most of which are much lower than mantle-zircon values, suggesting that oceanic crust altered at high temperature was involved in the mantle source. The integrated Sr–Nd–Hf–O isotopic compositions of these mafic–felsic intrusions can be explained by a model for the generation of the ELIP whereby a mantle plume interacted with the subducted Paleo-Tethyan oceanic lithospheric slab and overlying marine sediment. Our results suggest that the inclusion of the recycled altered oceanic slab in the mantle source of the ELIP led to its geochemical and, potentially, redox heterogeneity.

大型火成岩省的地幔衍生岩石的化学和同位素组成以及氧化还原条件变化很大；然而，这些异质性的起源仍不清楚。我们提供了峨眉山大火成岩省（ELIP）红格镁铁质-超镁铁质侵入体和相关正长岩的新地球化学和 Sr-Nd-Hf-O 同位素数据，并将它们与之前发表的 ELIP 中同时期侵入岩和火山岩的数据相结合，以限制 ELIP 和相关的世界级 Fe-Ti-V 氧化物沉积物的生成。红阁侵入体边缘带的岩石具有高钛玄武质成分，具有高初始⁸⁷ Sr/ ⁸⁶ Sr 比率（0.7084-0.7096）和非放射成因 εNd _（ -7.7 至 -5.9）和 ε_Hf（-6.0 到 -2.4）值，代表迄今为止在 ELIP 中观察到的高钛玄武岩系列中最富集的端元。边缘带岩石、时空关联的玄武岩和正长岩产生贫化的 Zr 和 Hf 含量，其中 Zr/Sm（7.1-38.3）和 Hf/Nd（0.05-0.12）的比率介于海洋沉积物和 OIB 之间。边缘带岩石的 Nd Hf 同位素组成绘制在陆地阵列上方，表明 Nd 和 Hf 同位素组成之间存在脱钩。俯冲洋壳、海洋沉积物和地幔橄榄岩之间的混合解释了富集的 Sr Nd 同位素组成 ZrHf 耗尽，以及这些样品中的 Nd 和 Hf 同位素组成之间的去耦，以及 ELIP 的其他镁铁质-长英质侵入体中。来自正长岩的锆石颗粒比边缘带岩石产生更多的放射性 ε _{Hf值 (+3.7 - +6.6) 并且具有 δ} ¹⁸O 值在3.9~5.7‰之间，大部分远低于地幔-锆石值，说明地幔源区与高温变质的洋壳有关。这些镁铁质-长英质侵入体的综合 Sr-Nd-Hf-O 同位素组成可以通过产生 ELIP 的模型来解释，其中地幔柱与俯冲的古特提斯洋岩石圈板片和上覆的海洋沉积物相互作用。我们的研究结果表明，在 ELIP 的地幔源中包含回收的蚀变洋板导致其地球化学和潜在的氧化还原异质性。