辽西大英昌岩体二长花岗岩地球化学、年代学特征及地质意义  

Geochemical and Geochronological Characteristics and Geological Significance of Monzogranite of Dayingchang Rock Mass in Western Liaoning

作　　者：孟繁敏 聂逢君[1] 吴德海 严兆彬[1] 曲晓梅 张成勇[1] 陈梦雅 张鑫 MENG Fan-min;NIE Feng-jun;WU De-hai;YAN Zhao-bin;QU Xiao-mei;ZHANG Cheng-yong;CHEN Meng-ya;ZHANG Xin(Faculty of Geoscience and Survey Engineerings East China Institute of Technology t Nanchang 330013,China;School of Resources,Environment and Jewelry t Jiangxi College of Applied Technology,Ganzhou 341000,China;Key Laboratory of Ionic Rare Earth Resources and Environment,Ministry of Natural Resources,Jiangxi College of Applied Technology,Ganzhou 341000,China)

机构地区：[1]东华理工大学地球科学学院,江西南昌330013 [2]江西应用技术职业学院资源环境与珠宝学院,江西赣州341000 [3]江西应用技术职业学院自然资源部离子型稀土资源与环境重点实验室,江西赣州341000

出　　处：《稀土》2022年第3期51-66,I0004,共17页Chinese Rare Earths

基　　金：国家自然科学基金项目(40272099);中国核工业地质局铀矿勘查项目(121201122078);核资源与环境国家重点实验室开放基金项目(2020NRE03)。

摘　　要：辽西大英昌岩体地处华北克拉通东北缘,大地构造位置在中朝准地台北缘的青龙-锦西断裂带上。通过对大英昌岩体黑云母二长岩花岗岩进行地球化学分析并结合锆石U-Pb同位素年龄探讨其地质意义。测试结果表明,黑云母二长花岗岩LA-ICP-MS锆石U-Pb同位素年龄为154.75 Ma±0.48 Ma,为中侏罗世岩浆活动的产物。岩石具有富Si、Al、Fe、Na、K,贫Mg、Ca、Ti、P等特征,为高钾钙碱性岩系列,属于岩浆晚期形成的高分异铝质-过铝质的I型花岗岩。轻稀土元素相对富集,重稀土元素相对亏损,大离子亲石元素Rb、Th、U、Ta等相对亏损,高场强元素Ba、Sr、Zr、Hf等相对富集,具较弱的铕和铈负异常,说明岩浆起源于岩石圈地幔,并发生部分熔融。晚中生代岩浆活动具有年轻化的特点,古太平洋板块向华北克拉通持续俯冲并交代岩石圈地幔,形成的幔源岩浆侵入带来热量使地壳发生部分熔融,并捕虏少量的幔源物质,形成了壳幔混合的岩浆。The Dayingchang rock mass is located in the eastern margin of the North China Craton, and its tectonic position is on the Qinglong-Jinxi fault zone on the northern margin of the Sino Korean paraplatform. This paper discusses its geological significance by geochemical analysis of monzonite granite of Dayingchang rock mass and zircon U-Pb isotopic age. The results show that the LA-ICP-MS zircon U-Pb isotopic age of biotite monzogranite is 154.75±0.48 Ma, which is the product of magmatism in the Middle Jurassic.The rock is rich in Si, Al, Fe, Na and K and poor in Mg, Ca, Ti and P, which is a series of high potassium calc alkaline rocks, belonging to highly differentiated aluminous peraluminous I-type granite formed in the late magmatic period. Light rare earth elements are relatively enriched, heavy rare earth elements are relatively depleted, large ion lithophile elements Rb, Th, U and Ta are relatively depleted, high field strength elements Ba, Sr, Zr and Hf are relatively enriched, with weak negative anomalies of europium and cerium, indicating that the magma originated from the lithospheric mantle and partially melted. The late Mesozoic Magmatic Activity is characterized by rejuvenation. The ancient Pacific plate continued to subduct to the North China Craton and replaced the lithospheric mantle. The formed mantle derived magma intrusion brought heat, partially melted the crust, and captured a small amount of mantle derived material, forming a crust mantle mixed magma.

关 键 词：二长岩花岗 锆石U-PB定年 大英昌岩体 华北克拉通 

分 类 号：P597.3[天文地球—地球化学]