SHRIMP zircon U-Pb dating in Jingshan migmatitic granite, Bengbu and its geological significance

The petrographic characteristics of Jingshan "migmatitic granite" and the occurrence of the magmatic zircons indicate that the granite was formed by normal crystallization of felsic melts. All zircons in the granite have inherited cores and fine-scale oscillatory zoning rims of magmatic origin. It is realized that the granite was formed at 160.2±1.3 Ma through dating magmatic zircons. The generation of the granitic magma could be related to the lithospheric mantle and/or lower crust delamination after the ultrahigh pressure metamorphism (UHPM) in Triassic. Most inherited zircons yield the ages of 217.1±6.6 Ma, which is consistent with the peak UHPM in the Dabie-Sulu orogenic belt. Some of the inherited zircons (433-722 Ma) constitute a discordia line with the upper intercept age of 850+85/-68 Ma and a lower intercept age of 261+100/-140 Ma. These ages imply that the granite could be derived from the partial melting of the crustal materials of the South China Block that was intensively superimposed by the UHPM. The UHPM could be the reason for the major Pb loss at ±220 Ma.

作 者： XU Wenliang WANG Qinghai YANG Debin LIU Xiaochun Guo Jinghui   作者單位： XU Wenliang,WANG Qinghai,YANG Debin(College of Earth Sciences,Jilin University,Changchun,130061,China)

LIU Xiaochun(Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing,100081,China)

Guo Jinghui(Institute of Geology & Geophysics,Chinese Academy of Sciences,Beijing,100029,China) 

刊 名： 中國(guó)科學(xué)D輯（英文版）  SCI 英文刊名： SCIENCE IN CHINA SERIES D  年，卷(期)： 2005 48(2)  分類(lèi)號(hào)： P6  關(guān)鍵詞： zircon   U-Pb dating   migmatitic granite   geological significance   Bengbu  

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