佳木斯地块中部岩浆岩锆石U-Pb年代学、地球化学及其大地构造意义  

Zircon U-Pb age and geochemistry of the magmatic rocks in the Jiamusi massif,NE China and their tectonic implications

作　　者：丛智超 孙丰月[1] 王冠 王英德[1] 霍亮[1] 潘忠翠 曹海龙[1] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]四川鑫顺矿业股份有限公司,成都610041

出　　处：《岩石学报》2016年第4期1141-1152,共12页Acta Petrologica Sinica

基　　金：中国地质调查局项目(1212011085485);国家自然科学基金项目(41272093)联合资助

摘　　要：佳木斯地块中部桦南隆起区广泛发育古生代-中生代岩浆岩,这些岩石的成因对深入探讨中亚造山带的形成演化具有重要的指示意义。LA-ICP-MS U-Pb定年和地球化学测试分析结果表明,研究区广泛分布的片麻状花岗闪长岩形成于中二叠世(267±2Ma),具有I型花岗岩的地球化学特征,表明其岩浆起源可能和俯冲板片产生的熔体有关,形成于岛弧构造环境。而正长花岗岩形成于中三叠世(244±2Ma),地球化学揭示其岩浆起源于下部陆壳物质的部分熔融,具有同碰撞花岗岩的地球化学特点。上述特征表明,研究区在中二叠世处于大陆边缘的构造背景,与古亚洲洋板块俯冲于佳木斯板块之下的构造作用相关,而中三叠世处于同碰撞的构造环境,俯冲此时已经消失,古亚洲洋已经最终闭合,因此三叠纪应该为中亚造山带重要的地质转折期。The Jiamusi massif is located in the key parts of the superimposed and transformed area between circum Pacific tectonic regime and Central Asian Orogenic Belt（ CAOB）. The north and south sides of the massif are adjacent to the Bureya block of the Russian Far East and Khanka block,respectively,which were called Bureya-Jiamusi-Khanka block. These areas had undergone the evolution of both the Paleo-Asian and the Pacific tectonic systems,and were characterized by the Paleozoic-Mesozoic complex amalgamation,making them the focus areas for study about the superimposition and transformation of circum Pacific and Paleo-Asian tectonic regimes. The Paleozoic-Mesozoic magmatic rocks are distributed widely in Huanan lift within the Jiamusi massif,which is significant for constraints on the regional tectonic evolution. The results of LA-ICP-MS zircon U-Pb dating and geochemical analyses indicate that the gneissic granites formed in Middle Permian（ 267 ± 2Ma） and have an affinity to I-type granite. They are relatively enriched in large ion lithophile elements（ LILEs） and light rare earth elements（ LREEs）,and depleted in heavy rare earth elements（ HREEs） and high field strength elements（ HFSEs）,suggesting that they were likely produced by the partial melting of subducted slab and formed in an island-arc environment. While the syenogranites formed in Middle Triassic（ 244 ± 2Ma）,and they have Si O_2=74. 29% ～ 74. 88%,Al2O3= 12. 99% ～ 13. 28%,（ Na_2 O ＋ K_2O） = 8. 61% ～ 9. 17%,and Na2 O/K2 O = 0. 35 ～ 0. 42,indicating that the syenogranites are alkaline series. In addition,A/NK-A/CNK illustration shows that the granites are peraluminous series,and they are characterized by enrichments in LREEs and LILEs,and depletions in HREEs and HFSEs. These geochemical characteristics are similar to the syn-collisional granite. The primary magmas for the syenogranites were generated by the partial melting of the lower continental crust. These evidences suggest that the magmatic rocks were formed in an

关 键 词：佳木斯地块 锆石U-PB测年 中亚造山带 中生代构造背景 

分 类 号：P618.51[天文地球—矿床学]