辽东半岛丹东地区晚侏罗世花岗岩成因及其对华北克拉通破坏的制约  

Petrogenesis of Late Jurassic Granitoids in the Dandong Region,Liaodong Peninsula:Constraints on the Destruction of the North China Craton

作　　者：程昌泉 刘锦[3] 张健 尹常青 高彭 钱加慧 CHENG Changquan;LIU Jin;ZHANG Jian;YIN Changqing;GAO Peng;QIAN Jiahui(Guangdong Provincial Key Lab of Geodynamics and Geohazards,School of Earth Sciences and Engineering,Sun Yat-sen University,Guangzhou 510275,Guangdong,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519082,Guangdong,China;College of Earth Sciences,Jilin University,Changchun 130061,Jilin,China)

机构地区：[1]中山大学地球科学与工程学院,广东省地球动力作用与地质灾害重点实验室,广东广州510275 [2]南方海洋科学与工程广东省实验室(珠海),广东珠海519082 [3]吉林大学地球科学学院,吉林长春130061

出　　处：《大地构造与成矿学》2023年第1期149-164,共16页Geotectonica et Metallogenia

基　　金：广东省引进人才创新团队(2016ZT06N331);中国博士后基金项目(2018M633210)联合资助。

摘　　要：辽东半岛广泛发育中生代花岗质岩浆作用,与华北克拉通东部岩石圈的大规模改造时空上紧密相关。以往研究多关注于晚三叠世和早白垩世两期岩浆活动,对晚侏罗世岩浆活动的研究相对较少。晚侏罗世作为华北克拉通东部破坏与岩石圈减薄过程的重要演化阶段,该时期的岩浆活动可以提供重要信息。本文着重选择辽东半岛具有代表性的晚侏罗世五龙岩体和虎山岩体为研究对象,其岩性为二长花岗岩,锆石U-Pb定年表明它们形成于161~158Ma。五龙和虎山二长花岗岩均具有高SiO_(2)(72.90%~75.02%)、Al_(2)O_(3)(13.40%~14.28%)含量和低MgO(0.14%~0.24%)、Fe_(2)O_(3)^(T)(0.79%~1.35%)含量,属于一套高钾钙碱性Ⅰ型花岗岩。五龙和虎山二长花岗岩富集轻稀土和大离子亲石元素(LILEs:Rb、Ba和K),亏损重稀土和高场强元素(HFSEs:Nb、Ta和Ti),具Eu负异常,与典型的岛弧岩浆岩地球化学特征类似。此外,样品还表现出较高Sr含量、Sr/Y值(16.9~61.8)和(La/Yb)N(13.9~60.7)值,以及低Y和Yb含量,与加厚下地壳成因的埃达克质岩石特征相似。锆石负ε_(Hf)(t)值(-46.0~-23.6)、古老的二阶段Hf模式年龄(4075~2694 Ma)以及微量元素特征揭示五龙和虎山二长花岗岩是在古太平洋板块俯冲作用下,中上地壳的新太古代-古元古代古老陆壳物质在外来流体参与下发生部分熔融的产物,丰富的流体活动可能促进了晚侏罗世-早白垩世期间华北克拉通东部的克拉通破坏和岩石圈减薄过程。Mesozoic magmatism is widely developed in the Liaodong Peninsula of the North China Craton. Previous studies mainly focused on the Late Triassic and Early Cretaceous magmatism. However, the role of the late Jurassic magmatism, which is closely related to the lithospheric thinning of the craton, is overlooked. Nevertheless, the late Jurassic is an important evolutional stage of the cratonic destruction. Thus, study on the late Jurassic magmatism can provide critical constraints on this issue. This study focuses on two representative late Jurassic plutons, i.e. the Wulong and Hushan plutons, which are mainly composed of monzogranite. Zircon U-Pb dating results show that the plutons were emplaced during ca. 161–158 Ma. They are high-K calc-alkaline series and Ⅰ-type granite with high SiO_(2)(72.90%–75.02%) and Al_(2)O_(3)(13.40%–14.28%) contents, but low MgO(0.14%–0.24%) and total Fe_(2)O_(3)(0.79%–1.35%) contents.The plutons are enriched in light rare earth elements(LREEs) and large iron lithophile elements(LILEs: Rb, Ba and K),depleted in heavy rare earth elements(HREEs) and high field strength elements(HFSEs: Nb, Ta and Ti), and display negative Eu anomalies, which are similar to those of island arc igneous rocks. In addition, they are characterized by high Sr contents, Sr/Y(16.9–61.8) and(La/Yb)N(13.9–60.7) ratios, and low Y and Yb contents, which are similar to those of adakites derived from partial melting of thickened lower crust. The negative ε_(Hf)(t)(-46.0 to-23.6) and old tDM2 ages(4075 to 2694 Ma) of zircons and whole-rock geochemistry indicate that the Wulong and Hushan monzogranites were generated by partial melting of Neoarchean-Paleoproterozoic crustal materials in the middle and upper crust with the participation of extraneous fluids, which were formed under the subduction of the paleo-Pacific plate. The abundant fluid activity may have facilitated the cratonic destruction and lithospheric thinning of the eastern North China Craton during the Late Jurassic to Early Cretaceous.

关 键 词：华北克拉通 辽东半岛 Ⅰ型花岗岩 古太平洋俯冲 克拉通破坏 

分 类 号：P588.12[天文地球—岩石学]