Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis: Constraints from TTG and potassic granitoids, North China Craton
Cyclic formation and stabilization of Archean lithosphere by accretionary orogenesis: Constraints from TTG and potassic granitoids, North China Craton
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增生造山作用导致太古代岩石圈的循环形成与稳定：华北克拉通TTG和钾质花岗岩的制约
DOI：
10.1002/2017tc004600
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发表时间：
2017
期刊：
影响因子：
4.2
通讯作者：
Wang Kang
中科院分区：
文献类型：
--
作者：
Wang Wei;Cawood Peter A.;Liu Shuwen;Guo Rongrong;Bai Xiang;Wang Kang
增生造山带是现代大陆生长的主要场所，但其在太古代陆壳发育中的作用仍是个谜。晚太古代出现了从英云闪长岩-奥长花岗岩-花岗闪长岩（TTG）到钾质花岗岩的多种花岗岩类组合，代表了大陆形成和稳定的重要时期。本文报道了华北东北部北方辽地体新太古代花岗质片麻岩的全岩地球化学和锆石U-Pb、Lu-Hf同位素数据。较古老的花岗岩质片麻岩（~2592-2537 Ma）定义了三个从东南向西北迁移的岩浆带，每个岩浆带都表现出从高压TTG到中/低压TTG和钾质花岗岩的共同岩浆演化。它们的锆石Hf（t）为+0.5至+8.7。在整个克拉里昂-克利珀顿地区出现了较年轻的~2529-2503 Ma钾质花岗岩类和TTG，其标志是变化的锆石Hf（t）为−4.7至+8.1，与区域高级变质作用同时代。岩石成因模拟和花岗岩类Sr/Y和（La/Yb）N的变化表明，地壳经历了幕式增厚和减薄，并通过钾质花岗岩类的发育和沉积序列而逐步演化。变质火山岩基底与花岗岩类具有拉斑玄武岩-钙碱性的亲合性，加上自上而下的逆冲推覆作用和与之相关的火山成因块状硫化物型铜锌矿床，表明北方的地壳形成是在一个具有SE-倾斜俯冲极性的增生造山带内循环的。地壳周期性增厚减薄与下行板块与上覆板块由进退关系转换为后退关系有关。~2530 Ma后，该增生系统增生到NCC（鞍山-本溪地体）的古大陆核，标志着岩石圈最终稳定。
Accretionary orogens are major sites of modern continental growth, yet their role in the development of Archean continental crust remains enigmatic. Diverse granitoid suites from tonalite‐trondhjemite‐granodiorite (TTG) to potassic granitoids appeared during late Archean, representing a period of major continental formation and stabilization. In this study, whole‐rock geochemical and zircon U‐Pb and Lu‐Hf isotopic data are reported for Neoarchean granitoid gneisses from the Northern Liaoning Terrane, northeastern North China Craton (NCC). Older granitoid gneisses (~2592–2537 Ma) define three magmatic zones migrating from southeast to northwest, each showing a common magmatic evolution from high‐pressure TTGs to medium‐/low‐pressure TTGs and potassic granitoids. They have depleted zircon ƐHf(t) of +0.5 to +8.7. Younger ~2529–2503 Ma potassic granitoids and TTGs occur throughout the terrane, which are marked by variable zircon ƐHf(t) of −4.7 to +8.1, and are coeval with regional high‐grade metamorphism. Petrogenetic modeling and changing Sr/Y and (La/Yb)Nof the granitoids suggest that the crust experienced episodic thickening and thinning and became progressively evolved through development of potassic granitoids and sedimentary successions. The metavolcanic basement to the granitoids display tholeiitic to calc‐alkaline affinities, together with the top‐to‐the‐northwest thrusting and associated volcanogenic massive sulfide‐type Cu‐Zn deposits, suggesting cyclic crustal formation of Northern Liaoning within an accretionary orogen with a SE‐dipping subduction polarity. Cyclic crustal thickening and thinning is related to tectonic switching from advancing to retreating relations between the downgoing and overriding plate. After ~2530 Ma, this accretionary system accreted to the ancient continental nucleus of NCC (Anshan‐Benxi Terrane), signifying final lithosphere stabilization.