| 青岛榴辉岩及胶南群片麻岩的锆石U－Pb年龄──胶南群中晋宁期岩浆事件的证据 |
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| 关键词:magmatic event U-Pb zircon ages gneiss of the Jiaonan Group |
| 基金项目:国家自然科学基金 |
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| U-Pb ZIRCON AGES OF ECLOGITE AND GNEISS FROMJIAONAN GROUP IN QINGDAO AREAEVIDENCE FOR THE JINNING MAGATIC EVENT INHISTORY OF THE JIAONAN GROUP |
| The Jiaonan group developed in the Su-Lu terrain is a basement of sudbucted continental crust onthe northern margin of the Yangtze Block.It is mainly composed of sneisses and a small amount of am-phiholites , marbles ,ultramafic rocks and eclogites, and was considered to De early and middle Protero-zoic rocks in literature. Abundant Sm-Nd and ￣(40)Ar/￣(39)Ar isotopic chronolosy results have demonstratedthat the Jiaonan group complex has been experienced a Triassic high-and ultrahigh-pressure metamor-phism which related to collision between the North China and Yangtze Block. However, there is no reli-able age for their protolithes. This paper reports two U-Pb zircon ages of eclogite and gueiss from theJiaonan group in Qindao area:(1)5 fractions of euhedral zircon from eclogite sive very similar ￣(206)Pb/￣(238)U and ￣(207)Pb/￣(235)U ap-parent ages below the concordia curve,thus can not forming a precise discordia line. Their ￣(207)Pb/￣(206) Pbappareiit ages of 682- 730 Ma perhape cloae to their crystalline age.(2 )5 fractions of euhedral zircons from srieiss give a precise discordia line.Its lower intercept ageof 202￣(+12)-14Ma is consistent with the Triassic ultrahigh pressure metamorphic time in this area.Its upperintercept age of 87￣+47￣(-45)Ma may indicate their crystalline age.Above results suggest that the gneisses in the Jiaonan group are not totally early and middle Pro-terozoic rocks and a part of them are latter Proterozoic plutonic intrusions. The protolith of eclogitefrom the Qingdao area may be a latter Proterozoic island are volcanics. Terefore, the Jinnig movement(700-1 000Ma)should be occurred in the Su-Lu terrain. |
| LI Shu-guang,CHEN Yi-zhi,GE Ming-jie,LIU De-liang,ZHANG Zhi-min,ZHANG Qiao-da,ZHAO Dun-min.1994.U-Pb ZIRCON AGES OF ECLOGITE AND GNEISS FROMJIAONAN GROUP IN QINGDAO AREAEVIDENCE FOR THE JINNING MAGATIC EVENT INHISTORY OF THE JIAONAN GROUP[J].Acta Geoscientica Sinica,15(1,2):35-36. |
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