SHRIMP U-Pb zircon dating for lamprophyre from Liaodong Peninsula: Constraints on the initial time of Mesozoic lithosphere thinning beneath eastern China

作     者：JIANG Yaohui JIANG Shaoyong ZHAO Kuidong NI Pei LING Hongfei LIU Dunyi 

作者机构：State Key Laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China Beijing SHRIMP Center Beijing 100037 China 

出 版 物：《Chinese Science Bulletin》 (CHINESE SCIENCE BULLETIN)

年 卷 期：2005年第50卷第22期

页      面：2612-2620页

核心收录：

学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 

基　　金：This work was financially supported by the National Natural Science Foundation of China (Grant No.40221301) 

主　　题：锆石 煌斑岩 中生代时期 岩石圈 辽东半岛 

摘      要：It is undebated fact that the lithospheric mantle beneath eastern China was considerably thinned during the Mesozoic time. However, it has no adequate evidence for the exact timing when the lithosphere thinning started. The Liaodong Peninsula is located in the eastern segment of the North China Craton and is one of the important domains to explore the event of lithosphere thinning. SHRIMP U-Pb zircon dating and geochemical study were carried out for the lamprophyre dike swarm that intruded into the magnesite ore-beds in the Dashiqiao Formation of Paleoproterozoic Liaohe Group at the Huaziyu magnesite ore district, Liaodong Peninsula. The results indicate that these lampro- phyre dikes were intruded in late Jurassic (155±4 Ma) and show some geochemical characteristics of potassic magmas. It is now accepted that the lithosphere thinning took place in the late Mesozoic, and the peak thinning stage occurred in early Cretaceous (130―120 Ma). Considering the potassic mafic magmatism marking the onset of the lithospheric thin- ning, we therefore suggest that the studied late Jurassic potassic lamprophyre dike swarm could imply that the late Jurassic is the time that lithosphere thinning started.