| 威海地区超高压变质花岗岩成因：锆石U-Pb定年和氧同位素研究 |
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| 关键词:Sulu orogenic belt metagranite zircon U-Pb dating oxygen isotopes property of protolith |
| 基金项目:本文为国家自然科学基金项目（编号：40334036)资助。 |
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| Zircon U-Pb Dating and Oxygen Isotopes of UHP Metagranite from Weihai Area, Northeast Sulu Orogenic Belt |
| Extremely δ18O-depleted zircons in granitic gneisses, whose a δ18O values are as low as -7.8‰, were found in Zaobuzhen of Weihai area, the northeastern end of the Sulu orogenic belt. SHRIMP zircon U-Pb ages and oxygen isotope compositions were determined for the low δ18O zircons. CL images reveal that the low δ18O zircons are primarily of igneous origin, but some grains have undergone metamorphic recrystallization. The igneous zircons from a graanitic gneiss sample yield a concordant U-Pb age of 760±49 Ma and an upper intercepted age of 751±27 Ma, indicating a protolith of middle Neoproterozoic age. Metamorphic zircons from the same sample yield a concordant U-Pb age of 232±4 Ma and a lower intercepted age of 241±33 Ma, pointing to the Triassic UHP metamorphism. Most of the igneous zircons have unusually variable δ18O values of -7.76‰~5.40‰, implying that the gneiss protolith was intruded as low δ18O magma generated by partial melting of altered rocks which had suffered intense water-rock interaction with a low δ18O fluid at high temperatures during Neoproterozoic. |
| TANG Jun,ZHENG Yongfei,WU Yuanbao,GONG Bing.2005.Zircon U-Pb Dating and Oxygen Isotopes of UHP Metagranite from Weihai Area, Northeast Sulu Orogenic Belt[J].Acta Geoscientica Sinica,26(z1):112-114. |
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