Middle-late permian I-type granitoids from the Diaobingshan region in the northern margin of the North China Craton: insight into southward subduction of the Paleo-Asian Ocean
Middle-late permian I-type granitoids from the Diaobingshan region in the northern margin of the North China Craton: insight into southward subduction of the Paleo-Asian Ocean
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华北克拉通北缘调兵山地区中晚二叠世I型花岗岩：洞察古亚洲洋南向俯冲
DOI：
10.1080/00206814.2020.1712556
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发表时间：
2021
影响因子：
2.6
通讯作者：
Bi Jun-Hui
中科院分区：
文献类型：
--
作者：
Jing Yan;Ji Zheng;Ge Wen-Chun;Dong Yu;Yang Hao;Bi Jun-Hui
对华北陆缘北方调兵山地区中晚二叠世花岗岩类进行了岩石学、锆石U-Pb年代学、全岩地球化学和原位锆石Hf同位素组成的综合研究，旨在探讨其年代学格架、岩石成因和构造意义。研究的花岗岩类广泛分布于长春-延吉缝合带南侧，主要由二长花岗岩和正长花岗岩组成，含少量石英二长岩。激光烧蚀电感耦合等离子体质谱（LA-ICP-MS）测得的锆石U-Pb年龄为262-256 Ma，反映了中晚二叠世岩浆活动。地球化学分析表明，岩石中含60.53- 73.33wt.% SiO2，12.60-18.35重量% Al 2 O3，3.50-8.10重量% K2 O，0.18-0.91重量% TiO 2，和0.22-1.01重量% MgO，呈弱过铝质（A/CNK = 0.86-1.01）、高钾钙碱性和钾玄质特征，指示I型花岗岩。它们还具有低Sr、高Yb的特征，反映了残余斜长石（即角闪岩相）的低压岩浆源区条件。这些花岗岩类还表现出典型的弧型岩浆岩的地球化学特征，富集大离子亲石元素（LILEs，如Rb，Ba和K）和轻稀土元素（LREEs），亏损高场强元素（HFSEs，如Nb，Ta，Ti和P）和重稀土元素（HREEs），表明它们形成于俯冲相关的环境。岩浆锆石的Hf同位素组成相对均一（εHf（t）=-1.4 ~+15.1），对应的两阶段模式（TDM 2）年龄为1839-348 Ma，表明它们是由古元古代-早元古代增生下地壳部分熔融形成的，古地壳物质的贡献较小。它们的地球化学特征和独特的岩石组合特征以及二叠纪花岗质岩浆活动的时空分布表明，华北克拉通北方边缘中晚二叠世花岗岩类的形成与向南的古亚洲洋壳俯冲作用有关。从这个和以前的研究数据使我们赞成一个双面的，早，晚二叠世俯冲模型，与古亚洲洋关闭后，晚二叠世。
An integrated study of the petrology, zircon U–Pb geochronology, whole–rock geochemistry, andin situzircon Hf isotopic compositions of middle–late Permian granitoids from the Diaobingshan region in the northern margin of the North China Craton (NCC) has been implemented, with the aim of investigating their geochronological framework, petrogenesis, and tectonic significance. The studied granitoids are widely distributed on the southern side of the Changchun–Yanji suture zone and comprise mainly monzogranite and syenogranite, with minor quartz monzonite. New zircon U–Pb data measured by laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) yield emplacement ages of 262–256 Ma, reflecting middle–late Permian magmatism. Geochemically, the rocks contain 60.53–73.33 wt.% SiO2, 12.60–18.35 wt.% Al2O3, 3.50–8.10 wt.% K2O, 0.18–0.91 wt.% TiO2, and 0.22–1.01 wt.% MgO, and exhibit weakly peraluminous (A/CNK = 0.86–1.01) and high-K calc–alkaline and shoshonitic characteristics, indicating I-type granite affinities. They are also characterized by low Sr and high Yb contents, reflecting low-pressure magma source conditions with residual plagioclase (i.e. amphibolite facies). These granitoids also exhibit geochemical characteristics typical of arc–type magmatic rocks, with enrichment in large ion lithophile elements (LILEs; e.g. Rb, Ba, and K) and light rare earth elements (LREEs), and depletion in high field strength elements (HFSEs; e.g. Nb, Ta, Ti, and P) and heavy rare earth elements (HREEs), indicating that they were formed in a subduction-related setting. Moreover, magmatic zircons from the studied rocks have relatively homogeneous Hf isotopic compositions (εHf(t) = – 1.4 to +15.1) and corresponding two–stage model (TDM2) ages of 1839–348 Ma, indicating that they were generated by partial melting of Paleoproterozoic–Phanerozoic accreted lower crust, with minor contributions of ancient crustal materials. Their geochemical characteristics and specific lithological assemblage, together with the temporal–spatial distribution of Permian granitic magmatism, indicate that the formation of middle–late Permian granitoids in the northern margin of the NCC was related to southward Paleo–Asian oceanic subduction. Data from this and previous studies lead us to favour a double-sided, early–late Permian subduction model, with the Paleo–Asian Ocean closing after the late Permian.