The spatiotemporal evolution of magmatism is pivotal to understand the growth mechanism and evolution of continental crust during major orogenic cycles. In this study, we investigate the extensive Early Paleozoic magmatic rock suites (487-390 Ma) from the East Kunlun Orogen (EKO), and attempt to gain insights into the growth and reworking of continental crust. The geodynamic setting of the EKO in the Early Paleozoic can be divided into early compressional setting during oceanic subduction and continental collision (stage 1: 487–427 Ma) and a subsequent extensional setting associated with slab break-off and post-collisional collapse (stage 2: 426–390 Ma). In stage 1, regional magmatism was dominated by I-type granitic rocks and lithosphere mantle-derived mafic rocks. The I-type granitic rocks in this stage incorporated materials from coeval mafic rocks, which were derived from partial melting of a continuously enriched mantle wedge resulted from interaction with oceanic slab. Modeling of Hf isotope reveals that at least 65% of juvenile materials were introduced to the continental crust by magmatism in this stage. In addition, the slab fluids were dominated by interaction with the mantle wedge during 487–450 Ma (stage 1–1) while the slab melts started to contribute to regional magmatism during 450–427 Ma (stage 1–2) with or without interaction with the mantle wedge, and the crustal growth rate significantly increased from stage 1–1 to stage 1–2. During the extensional setting in stage 2, large-scale mafic magma with a source of asthenosphere mantle underplated /intruded into the lower continental crust, providing heat for the crustal reworking, and producing the juvenile mafic lower continental crust. The granitic rocks in this period were dominated by S- and A-types with an age range of 426–418 Ma (stage 2–1), I-type granites at 417–408 Ma (stage 2–2), and A-type granites during 406–390 Ma (stage 2–3). The S-type and A-type granites in these periods were derived from the reworking of crustal sediments and calc-alkaline granitoids, respectively, whereas the I-type granites in stage 2–2 were the products of the reworking of mafic lower continental crust. The factors resulting in the generation of different granitic rocks in these substages are attributed to the slab break-off at stage 2–1, thickened lithosphere blocked the heat input from the asthenosphere to felsic crust at stage 2–2, and the lithosphere delamination at stage 2–3. Crustal maturity was enhanced during these periods through reworking, bringing more silicic units with higher incompatible elements to the shallower crust. Thus, magmatism sourced from lithosphere mantle and oceanic slab contributed to the continental crust growth in the early compressional setting, whereas crustal reworking was the key to enhance the crustal maturity in the later extensional setting.

岩浆作用的时空演化是理解主要造山旋回中大陆地壳生长机制和演化的关键。在这项研究中，我们调查了东昆仑造山带（EKO）广泛的早古生代岩浆岩组（487-390 Ma），并试图深入了解大陆地壳的生长和改造。早古生代 EKO的地球动力学背景可分为大洋俯冲和大陆碰撞期间的早期挤压背景（第 1 阶段：487-427 Ma）和随后与板片断裂和碰撞后塌陷相关的伸展背景（阶段2：426-390 毫安）。第一阶段区域岩浆活动以I型花岗岩和岩石圈地幔衍生为主镁铁质岩石。这一阶段的I型花岗质岩石含有来自同时代镁铁质岩的物质，这些物质来自与大洋板片相互作用产生的连续富集的地幔楔部分熔融。Hf同位素模型显示，在这个阶段，至少有65%的幼体物质是通过岩浆作用引入大陆地壳的。此外，板片流体在 487-450 Ma（1-1 阶段）以与地幔楔的相互作用为主，而板片熔体在 450-427 Ma（1-2 阶段）开始对区域岩浆活动做出贡献，无论有无相互作用随着地幔楔的作用，地壳生长速率从阶段 1-1 到阶段 1-2 显着增加。在第 2 阶段的伸展环境中，具有软流圈源的大规模镁铁质岩浆地幔垫底/侵入下大陆地壳，为地壳再加工提供热量，并产生幼年镁铁质下大陆地壳。该期花岗岩以 S 型和 A 型为主，年龄范围 426～418 Ma（2～1 期），I 型花岗岩 417～408 Ma（2～2 期），A-类型花岗岩在 406-390 Ma（阶段 2-3）。这些时期的S型和A型花岗岩分别来自地壳沉​​积物和钙碱性花岗岩的改造，而2-2期的I型花岗岩是镁铁质下陆壳改造的产物. 在这些亚阶段产生不同花岗岩的因素归因于第2-1阶段的板片断裂，加厚的岩石圈在第2-2阶段阻止了从软流圈到长英质地壳的热量输入，在第 2-3 阶段分层。在这些时期，通过改造提高了地壳成熟度，将更多具有更高不相容元素的硅质单元带入了较浅的地壳。因此，来自岩石圈地幔和洋板的岩浆作用有助于早期挤压环境中的大陆地壳生长，而地壳改造是后期伸展环境中提高地壳成熟度的关键。