To well understand the dynamic mechanism of Cretaceous magmatism flare‐up in the southern Sulu Orogen (SSO), the ages and petrogenesis of Qingyun monzogranites and the other coeval granitic plutons in the SSO are investigated herein through an integrated study of petrology, geochemistry, geochronology, and Sr–Nd–Pb–Hf isotopes. The studied granites are characterized by high Si, weak peraluminous, poor Fe and Mg, rich alkaline and high K. They are also characterized by enriched light rare earth element (LREE) and depleted heavy rare earth element (HREE), with the strong fractionation between LREE and HREE [(La/Yb)_N = 19.71–45.78]. Besides, the rocks are depleted in HFSEs (i.e., Ta, Nb, Ti, and P) and relatively enriched in Pb and LILEs (i.e., Rb, Th, and K), with moderate negative Eu anomalies (δEu = 0.62–0.72). The lithogeochemical characteristics indicate that they are highly differentiated I‐type granite. Zircon U–Pb dating shows the age of monzogranite is 126.7 ± 1.0 Ma, which formed by magmatism in the Early Cretaceous. In addition, all the samples have low (²⁰⁶Pb/²⁰⁴Pb)_i, (²⁰⁷Pb/²⁰⁴Pb)_i, and (²⁰⁸Pb/²⁰⁴Pb)_i (15.927–16.173, 15.356–15.383, and 37.084–37.412, respectively), similar to coeval felsic and mafic rocks from the Sulu Orogen and the North China Craton (NCC). Moreover, they display negative εHf(t) values (−21.53 to −34.43) with T_DM2 model ages (2.55–3.35 Ga). Both the εHf(t) and T_DM2 model ages indicate that they are derived from partial melting of the NCC Neoarchean continental crust. Therefore, it is believed that the rocks are primarily derived from partial melting of lower crust in granulite facies beneath the moderate pressure (0.8–1.3 GPa), corresponding to a depth of 35–45 km, within an extensional tectonic environment. The mineral fractional crystallization could occur in the diagenetic process. The delamination of lithosphere and the underplating of upwelling asthenospheric magma, which are reinforced by the subduction of the Palaeo‐Pacific Plate, could be the main factors to lead to partial melting of lower crust.

中文翻译：

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苏鲁造山带南部白垩纪花岗岩的成岩作用：对碰撞后岩浆活动爆发的影响

为了全面了解苏鲁造山带南部白垩纪岩浆活动的动力学机制，本文通过对岩石学，地球化学，地球年代学的综合研究，研究了青云山辉长花岗岩和其他同代花岗岩体的年龄和成岩作用。和Sr–Nd–Pb–Hf同位素。所研究的花岗岩具有高硅，弱铝质，贫铁和镁，富碱和高钾的特征。它们还具有富轻稀土元素（LREE）和贫化重稀土元素（HREE）以及强分馏的特征。在LREE和HREE [（La / Yb）_N= 19.71–45.78]。此外，岩石中的HFSE（即Ta，Nb，Ti和P）贫乏，而Pb和LILE（即Rb，Th和K）相对富集，且Eu异常中等（δEu= 0.62-0.72）。 。岩石地球化学特征表明它们是高度分化的I型花岗岩。锆石U–Pb测年表明，辉长岩的年龄为126.7±1.0 Ma，这是由白垩纪早期的岩浆作用形成的。此外，所有样本都具有较低的（²⁰⁶ Pb / ²⁰⁴ Pb）_i，（²⁰⁷ Pb / ²⁰⁴ Pb）_i和（²⁰⁸ Pb / ²⁰⁴ Pb）_i（分别为15.927–16.173、15.356–15.383和37.084–37.412），类似于来自苏鲁造山带和华北克拉通（NCC）的中世纪长英质和镁铁质岩石。此外，随着T _DM2模型年龄（2.55-3.35 Ga），它们显示负εHf（t）值（−21.53至-34.43 ）。εHf（t）和T _DM2模型年龄表明，它们是由NCC新古宙大陆壳的部分融化产生的。因此，可以认为，岩石主要来自于伸展构造环境中中等压力（0.8-1.3 GPa）下对应于35-45 km深度的花岗石相中下地壳的部分熔融。矿物分级结晶可能发生在成岩过程中。古太平洋板块俯冲作用加强了岩石圈的分层和上升流的软流圈岩浆的下沉，可能是导致下地壳部分熔融的主要因素。