Late Paleozoic large-scale transcurrent tectonics and synkinematic intrusions are prominent features in the Eastern Tianshan segment of the southwestern Central Asian Orogenic Belt. However, the spatial and temporal relationship between synkinematic intrusions and crustal-scale shear zones remains unclear. Here we report petrology, geochemistry, and geochronology of the Qiziltag pluton associated with the Kanggur-Huangshan Shear Zone (KHSZ) with a view to characterize the spatial and temporal relationship between synkinematic intrusions and large-scale transcurrent shearing. Field relations and zircon U-Pb ages indicate that the Qiziltag pluton was formed through two stages of magmatism, with earlier stage granitoids (gneissic biotite granite: 288.9 ± 1.9 Ma, biotite monzogranite: 291.5 ± 1.7 Ma, K-feldspar granite: 287.9 ± 3.1 Ma), and later stage bimodal intrusions (biotite quartz monzonite: 278.5 ± 1.8 Ma, gabbro: 278.1 ± 2.3 Ma). The earlier stage granitoids are high-K calc-alkaline, enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs; e.g., Rb, Th, and U), and depleted in high field strength elements (HFSEs; e.g., Nb, Ta, and Ti). Combined with their depleted isotopic compositions (εNd(t) = +6.29 to +7.48) and juvenile model ages (TDM2 = 450–610 Ma), we infer that the granitoids were derived from juvenile lower crust in a post-collisional tectonic transition (from compression to extension). The structural and temporal features indicate that the earlier stage (ca. 290 Ma) granitoids formed prior to the regional large-scale dextral strike slip. The later stage bimodal intrusions are dominated by biotite quartz monzonite as the felsic member and gabbro as the mafic component. The biotite quartz monzonite is high-K calc-alkaline with enriched LREEs and LILEs (e.g., Rb, Th, and U), and depleted HFSEs (e.g., Nb, Ta, and Ti), whereas the gabbro is subalkalic with depleted LREEs and HFSEs (e.g., Nb and Ta), resembling normal mid-ocean ridge basalt features. The bimodal intrusions show similar isotopic compositions (εNd(t) = +6.41 to +6.72 and εHf(t) = +9.55 to + 13.85 for biotite quartz monzonite; εNd(t) = +9.13 to +9.69 and εHf(t) = +4.80 to +14.07 for gabbro). These features suggest that the later stage (ca. 280 Ma) bimodal intrusions were derived from partial melting of depleted mantle and anatectic melting of lower crust materials induced by synchronous underplating of basaltic magma in a post-collisional extension. The structural features of the bimodal intrusions indicate that the later stage (ca. 280 Ma) magmatism was coeval with the development of the KHSZ. In conjunction with spatial and temporal evolution of magmatism and sedimentary records of Eastern Tianshan, we infer that transition between the northward closure of the North Tianshan Ocean and subsequent collision between the Central Tianshan Massif and the Qoltag Arc belt occurred at ca. 300 Ma.

中文翻译：

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中亚造山带东天山晚古生代构造从俯冲到碰撞后伸展的过渡

晚古生代的大规模横流构造和运动学侵入是西南中亚造山带东天山段的主要特征。然而，运动学入侵与地壳尺度剪切带之间的时空关系仍然不清楚。在这里，我们报道了与Kanggur-Huangshan剪切带（KHSZ）相关的Qiziltag岩体的岩石学，地球化学和地质年代学，旨在表征突触运动与大规模横流剪切之间的时空关系。场关系和锆石U-Pb年龄表明，齐齐尔塔格岩体是通过两个阶段的岩浆作用形成的，具有早期的花岗岩类（片麻岩黑云母花岗岩：288.9±1.9 Ma，黑云母辉长花岗岩：291.5±1.7 Ma，钾长石花岗岩：287.9± 3.1 Ma），后期双峰侵入（黑云母石英蒙脱石：278.5±1.8 Ma，辉长岩：278.1±2.3 Ma）。早期的类花岗岩是高K钙碱性盐，富含轻稀土元素（LREE）和大离子亲石元素（LILE；例如Rb，Th和U），而贫化了高场强元素（HFSE）；例如，Nb，Ta和Ti）。结合其耗尽的同位素组成（εNd（t）= +6.29至+7.48）和青少年模型年龄（TDM2 = 450–610 Ma），我们推断花岗岩类是在碰撞后的构造转变中源自青少年下地壳的（从压缩到扩展）。结构和时间特征表明，较早的阶段（约290 Ma）花岗岩在区域大规模右旋走滑之前形成。后期的双峰侵入以黑云母石英蒙脱石为长英质成分，辉长岩为黑镁质成分为主。黑云母石英蒙脱石是高K钙碱性物质，富含LREE和LILE（例如Rb，Th和U）和HFSE贫乏（例如Nb，Ta和Ti），而辉长岩是次碱性的，具有LREE和HFSE（例如Nb和Ta），类似于正常的洋中脊玄武岩特征。双峰侵入显示出相似的同位素组成（黑云母石英蒙脱石的εNd（t）= +6.41至+6.72和εHf（t）= +9.55至+ 13.85;εNd（t）= +9.13至+9.69和εHf（t）= gabbro为+4.80至+14.07）。这些功能建议您在后期（ca. 280 Ma）的双峰侵入源于枯竭的地幔的部分熔融和在碰撞后延伸中玄武岩浆的同步欠镀引起的下地壳物质的先熔熔融。双峰侵入的结构特征表明，后期（约280 Ma）岩浆作用与KHSZ的发展同时发生。结合东天山的岩浆作用的时空演化和沉积记录，我们推断北天山大洋的北向封闭与随后的中天山地块与Qoltag弧带之间的碰撞发生在约3月。300毫安 结合东天山的岩浆作用的时空演化和沉积记录，我们推断北天山大洋的北向封闭与随后的中天山地块与Qoltag弧带之间的碰撞发生在约3月。300毫安 结合东天山的岩浆作用的时空演化和沉积记录，我们推断北天山大洋的北向封闭与随后的中天山地块与Qoltag弧带之间的碰撞发生在约3月。300毫安