Abstract The Sadaigoumen porphyry Mo deposit lies on the northern margin of the North China Craton. Molybdenum mineralization occurs mainly as veins and veinlets, or is disseminated within alkali feldspar granite and granite porphyry, which yield weighted-mean 206Pb/238U ages (±2σ) of 243.7 ± 1.6 to 242.2 ± 2.0 Ma and 240.0 ± 1.7 Ma, respectively. Re Os dating of molybdenite from Stage 3 mineralization yields an isochron age of 238.0 ± 1.9 Ma. The Sadaigoumen ore-related granites have petrological, mineralogical, and geochemical characteristics of I-type granite. Ore-related granites exhibit low (87Sr/86Sr)i ratios of 0.710256–0.711463, negative eNd(t) values of −16.4 to −15.4 with corresponding TDM2 (Nd) ages of 2061–1870 Ma, and negative eHf(t) values of −21.2 to −11.2 with corresponding TDM2 (Hf) ages of 2614–1983 Ma, indicating that the primary magma was derived by partial melting of ancient lower crust. In chondrite- and primitive-mantle-normalized trace element diagrams, the Sadaigoumen ore-related granites are characterized by moderate enrichment of light rare earth elements (REE) relative to heavy REE, moderate to strong negative Nb, Ta, Zr, Hf, and Ti anomalies, and increasing Rb/Sr ratios with decreasing Sr content, all attributed to fractional crystallization. Fractionation of amphibole, muscovite, and possibly minor biotite and garnet (and/or zircon) produced the variations in most elements. Together with the regional geology, the data imply that the Sadaigoumen ore-related granites and corresponding mineralization formed in a syn-collision to post-collision transitional setting during the Early–Middle Triassic. These fractionated Triassic alkaline granites or syenogranites potentially contain new porphyry Mo deposits.

中文翻译：

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华北克拉通北缘萨岱沟门花岗岩成因及找钼意义

摘要 萨岱沟门斑岩钼矿床位于华北克拉通北缘。钼矿化主要以脉和细脉形式出现，或在碱性长石花岗岩和花岗斑岩中浸染，其产生的加权平均206Pb/238U年龄（±2σ）分别为243.7±1.6至242.2±2.0 Ma和240.0±1.0 来自第 3 阶段矿化的辉钼矿的 Re Os 测年产生了 238.0 ± 1.9 Ma 的等时线年龄。萨岱沟门成矿花岗岩具有I型花岗岩的岩石学、矿物学和地球化学特征。与矿石有关的花岗岩具有 0.710256–0.711463 的低 (87Sr/86Sr)i 比率，负 eNd(t) 值为 -16.4 至 -15.4，相应的 TDM2 (Nd) 年龄为 2061–1870 Ma，以及负 eHf(t) 值-21.2 至 -11.2，相应的 TDM2 (Hf) 年龄为 2614-1983 Ma，表明原生岩浆是由古代下地壳的部分熔融产生的。在球粒陨石-原始地幔-归一化微量元素图谱中，与重稀土元素相比，赛台沟门​​矿相关花岗岩中度富集轻稀土元素（REE），中至强负负 Nb、Ta、Zr、Hf 和Ti 异常以及 Rb/Sr 比率随着 Sr 含量的降低而增加，都归因于分步结晶。角闪石、白云母和可能的少量黑云母和石榴石（和/或锆石）的分馏产生了大多数元素的变化。结合区域地质情况，这些数据表明，在早-中三叠世期间，在同碰撞到碰撞后过渡环境中形成了与萨台沟门矿石有关的花岗岩和相应的矿化。