| SHRIMP U-Pb Dating of Zircons of a Dark Eclogite and aGarnet-bearing Gneissic Granitic Rock from Bixiling, EasternDabie Area, Anhui Province: Isotope Chronological Evidenceof Neoproterozoic UHP Metamorphism |
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| 作者姓名： | CHENG Yuqi LIU Dunyi I.S. WILLIAMS JIAN Ping ZHUANG Yuxun and GAO Tianshan Institute of Geology Chinese Academy of Geological Sciences Barwanzhuang Rd. Beijing China Research School of Earth Sciences Australian National University G.P.O Box Canberr A.C.T. Australia Anhui Geological Survey Changjiangdong Rd. Hefei Anhui China |
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| 作者单位： | CHENG Yuqi，LIU Dunyi，I.S. WILLIAMS，JIAN Ping，ZHUANG Yuxun and GAO Tianshan Institute of Geology，Chinese Academy of Geological Sciences，26 Barwanzhuang Rd.，Beijing 100037，China Research School of Earth Sciences，Australian National University，G.P.O Box 4，Canberra，A.C.T.，2601，Australia Anhui Geological Survey，115 Changjiangdong Rd.，Hefei 230011，Anhui，China |
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| 摘 要： | The paper reports SHRIMP U-Pb zircon data of a dark eclogite and a post-eclogite garnet-bearing gneissic granitic rock from the Bixiling area, Yuexi County, Anhui Province, in the eastern Dabie Mountains. The eclogite, which is metamorphosed basic tuff, contains very scarce zircons in omphacite or garnet, but more zircons in quartz. They usually exhibit a double-layered texture, as shown clearly in cathodoluminescence images. Their inner main parts give a 206Pb/238U age of 757±7 Ma, representing the approximate age of the high-pressure (HP)- ultrahigh-pressure (UHP) metamorphic event during which the eclogite was formed. The outer peripheral parts of the zircons, which have been modified by late-stage fluids, give an age of 223±3 Ma. The granitic rock contains more zircons of anatectic origin found mostly in feldspar and quartz and usually also showing a similar composite texture. The inner main parts of the anatectic zircons with oscillatory zoning give a 206Pb/238U age of 727±15 Ma for the approxim
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SHRIMP U-Pb Dating of Zircons of a Dark Eclogite and aGarnet-bearing Gneissic Granitic Rock from Bixiling, EasternDabie Area, Anhui Province: Isotope Chronological Evidenceof Neoproterozoic UHP Metamorphism |
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| Authors: | CHENG Yuqi LIU Dunyi IS WILLIAMS JIAN Ping ZHUANG Yuxun and GAO Tianshan Institute of Geology Chinese Academy of Geological Sciences Barwanzhuang Rd Beijing China Research School of Earth Sciences Australian National University GPO Box Canberr ACT Australia Anhui Geological Survey Changjiangdong Rd Hefei Anhui China |
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| Abstract: | The paper reports SHRIMP U‐Pb zircon data of a dark eclogite and a post‐eclogite garnet‐bearing gneissic granitic rock from the Bixiling area, Yuexi County, Anhui Province, in the eastern Dabie Mountains. The eclogite, which is metamorphosed basic tuff, contains very scarce zircons in omphacite or garnet, but more zircons in quartz. They usually exhibit a double‐layered texture, as shown clearly in cathodoluminescence images. Their inner main parts give a 206Pb/238U age of 757±7 Ma, representing the approximate age of the high‐pressure (HP)‐ ultrahigh‐pressure (UHP) metamorphic event during which the eclogite was formed. The outer peripheral parts of the zircons, which have been modified by late‐stage fluids, give an age of 223±3 Ma. The granitic rock contains more zircons of anatectic origin found mostly in feldspar and quartz and usually also showing a similar composite texture. The inner main parts of the anatectic zircons with oscillatory zoning give a 206Pb/238U age of 727±15 Ma for the approximate age of the emplacement of the granitic rock, and their outer parts, an age of 219±3 Ma for a similar or even the same fluid event. It is thus suggested that the HP‐UHP metamorphism of the Bixiling eclogite facies rocks took place during the Neoproterozoic Jinningian, and the Indosinian age values may only represent a late event in the nature of fluid activity. |
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| Keywords: | Bixiling dark eclogite garnet-bearing gneissic granitic rock Neoproterozoic Jinningian SHRIMP dating |
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