SHRIMP U-Pb zircon dating for lamprophyre from Liaodong Peninsula: Constraints on the initial time of Mesozoic lithosphe

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 lamprophyre 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 thinning, 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.

作 者： JIANG Yaohui JIANG Shaoyong ZHAO Kuidong NI Pei LING Hongfei LIU Dunyi   作者單位： JIANG Yaohui,JIANG Shaoyong,ZHAO Kuidong,NI Pei,LING Hongfei(State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing 210093, China)

LIU Dunyi(Beijing SHRIMP Center, Beijing 100037, China) 

刊 名： 科學(xué)通報（英文版）  SCI 英文刊名： CHINESE SCIENCE BULLETIN  年，卷(期)： 2005 50(22)  分類號： P3  關(guān)鍵詞： lamprophyre   SHRIMP U-Pb zircon dating   lithosphere thinning   Liaodong Peninsula  

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