Repeated modification of lithospheric mantle in the eastern North China Craton:Constraints from SHRIMP zircon U-Pb dating of dunite xenoliths in western Shandong  

作　　者：YANG DeBin XU WenLiang GAO Shan XU YiGang PEI FuPing 

机构地区：[1]College of Earth Sciences,Jilin University,Changchun 130061,China [2]CAS Key Laboratory oflsotopic Geochronology and Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences Guangzhou 510640,China [3]State Key Laboratory of Geological Processes and Mineral Resources,China University ofGeosciences,Wuhan 430074,China

出　　处：《Chinese Science Bulletin》2012年第6期651-659,共9页

基　　金：supported by the National Basic Research Program of China (2009CB825005);the National Natural Science Foundation of China (90814003,90714010,91014004 and 41002018)

摘　　要：Four dunite xenoliths from the Tietonggou intrusion of western Shandong,China,were subjected to SHRIMP zircon U-Pb dating to constrain timing of the North China Craton(NCC) destruction,a topic of much controversy.Cathodoluminescence images revealed that 15 of the 18 zircon grains from the xenoliths display striped absorption.The rest showed oscillatory growth zoniation.All the zircons had variable contents of Th(49-3569 ppm;average,885 ppm) and U(184-5398 ppm;average,1277 ppm),and variable Th/U ratios(0.15-2.04).These zircon characteristics indicate a magmatic origin.The zircon age data can be divided into five groups:131-145,151-164,261-280,434-452,and 500-516 Ma.Group I(131-145 Ma) is consistent with timing of formation of the Tietonggou high-Mg diorites.Group II(151-164 Ma) is similar in age to Middle-Late Jurassic magmatism in the eastern NCC,which included both mantle-derived and intensive crust-derived magmatism.Group III(261-280 Ma) is similar in age to the Emeishan large igneous province,and Group IV(434-452 Ma) is similar in age to Paleozoic high-silica magmatism in the eastern NCC.Group V(500-516 Ma) may correspond to the global Pan-African event.Results indicate repeated modification of lithospheric mantle in the eastern NCC,and suggest that the most intensive modification occurred in the late Mesozoic(131-164 Ma).Four dunite xenoliths from the Tietonggou intrusion of western Shandong, China, were subjected to SHRIMP zircon U-Pb dating to constrain timing of the North China Craton （NCC） destruction, a topic of much controversy. Cathodoluminescence images revealed that 15 of the 18 zircon grains from the xenoliths display striped absorption. The rest showed oscillatory growth zoni- ation. All the zircons had variable contents of Th （49-3569 ppm; average, 885 ppm） and U （184-5398 ppm; average, 1277 ppm）, and variable Th/U ratios （0.15-2.04）. These zircon characteristics indicate a magmatic origin. The zircon age data can be divided into five groups： 131-145, 151-164, 261-280, 434-452, and 500-516 Ma. Group I （131-145 Ma） is consistent with timing of formation of the Tietonggou high-Mg diorites. Group II （151-164 Ma） is similar in age to Middle-Late Jurassic magmatism in the eastern NCC, which included both mantle-derived and intensive crust-derived magmatism. Group III （261-280 Ma） is similar in age to the Emeishan large igneous province, and Group IV （434-452 Ma） is similar in age to Paleozoic high-silica magmatism in the eastern NCC. Group V （500-516 Ma） may correspond to the global Pan-African event. Results indicate repeated modification of lithospheric mantle in the eastern NCC, and suggest that the most intensive modification occurred in the late Mesozoic （131-164 Ma）.

关 键 词：锆石U-PB SHRIMP 橄榄岩捕虏体 华北克拉通 岩石圈地幔 华北东部 修改 鲁西 

分 类 号：P588.121[天文地球—岩石学] P183.2[天文地球—地质学]