Tonalite-trondhjemite-granodiorite (TTG) gneisses and granitic gneisses are widely distributed in the Early Precambrian metamorphic basement of Jiaobei terrane. In this study, we link cathodoluminescence (CL) images, U-Pb ages, and trace element compositions obtained from distinct zircon domains of complex zircons to unravel the origin, polyphase protolith and metamorphic ages of TTG gneisses and granitic gneisses in Jiaobei terrane. Zircons separated from 6 studied samples record four groups of magmatic ages of 2909 ± 13Ma, 2738 ±23Ma, 2544 ± 15 ～2564 ± 12Ma and 2095 ± 12Ma, and two groups of metamorphic ages of 2504 ± 16 ～2513 ±32Ma and 1863 ±41 Ma. A combined study of previously geochemical and Nd isotope data provides insight into the nature of TTG gneisses and granitic gneisses in the Jiaobei terrane. The TTG magmatic event took place at ～2738Ma may represent the major crust-growth episode. In contrast, the magmatic event took place at 2544 ～ 2564Ma may represent the remelting of the older crustal materials, which was the most significantly magmatic event in the North China Craton (NCC). Whereas the magmatic event took place at ～ 2095Ma may reflect a period of magmatism related to an extension setting along the Jiao-Liao-Ji tectonic belt A Neoarchean metamorphic event (2504 ～ 2513Ma) may be linked to the underplating of large amounts of mantle-derived magmas which are considered to be related to upwelling mantle plumes (hot-spots). A Paleoproterozoic metamorphic event ( ～ 1863Ma) recorded in the TTG gneisses, however, is consistent with the timing of high-pressure (HP) granulite facies metamorphism of mafic and pelitic HP granulites in Jiaobei terrane, implying the TTG gneisses also experienced the Paleoproterozoic HP granulite facies metamorphism. These evidences indicate that a significant continent-continent collision event did take place within the Jiaobei terrane at Paleoproterozoic.%本文采用LA-ICP-MS技术,对胶北地体TTG片麻岩和花岗质片麻岩中格石进行系统原位U-Pb定年和稀土、微量元素的分析,发现研究区早前寒武变质结晶基底存在多期岩浆-变质热事件.4件TTG片麻岩和2件花岗质片麻岩锆石样品记录了2909±13Ma、2738±23Ma、2544±15-2564±12Ma和2095±12Ma4组岩装事件年龄,以及2504±16-2513±32Ma和1863±41Ma2组变质事件年龄.结合以往TTG片麻岩和花岗质片麻岩的地球化学及Nd同位素研究发现,约2738Ma的TTG 岩浆事件可能代表胶北地体地壳最主要的生长事件,而2544-2564Ma的岩浆事件则可能代表古老地壳重熔的最强烈岩浆事件,约2095 Ma岩浆事件则反映了胶-辽-吉构造带内部在该时期与地壳拉张作用有关的岩浆活动.2504-2513Ma是研究区以及华北克拉通早前寒武基底最主要的一期变质热事件,可能与地慢柱(热点)岩浆的底侵作用有关,而TCG片麻岩记录的约1863Ma的变质年龄与研究区基性和泥质高压麻粒岩相岩石记录的麻粒岩相变质时代一致,暗示TTG片麻岩可能也经历了古元古代高压麻粒岩相变质作用,上述研究进一步表明胶北地体在古元古代的确存在一期陆-陆碰撞的重要造山事件.该项研究成果对于进一步深入探讨胶北乃至华北克拉通早前寒武纪变质基底的形成演化、岩浆-变质热事件序列及其构造背景具有重要的科学意义.
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