| 鄂西崆岭杂岩的组成,时代及地质演化 |
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| 关键词:Sm_Nd U_Pb geochronology Kongling complex geologic evolution |
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| The Constitute,Geochronology and Geologic Evolution of the Kongling Complex, Western Hubei |
| The Kongling complex,an important part of the basememt block for the Yangtze platform,is exposed in the core of the Huangling Arch in western Hubei province .It consists of basement gneisses,including mainly of grey gneisses,amphibolites and leptynites,and supracrus_ tal rocks composed of khondalite series and amphibole schists.21 samples,including amphibolites ,grey gneisses and the minerals that compose the amphibolite have been dated by Sm_Nd method.An isochron based on the Sm_Nd data of 13 amphibolites gives an age of 3 290±170 Ma(2σ),another one isochron involving all the Sm_Nd data of amphibolites and grey gneisses gives an age of 3 150±79 Ma(2σ),the third one including two amphibolites and two amphiboles and two plagioclases gives an age of 3 460±200 Ma(2σ).By applying the U_Pb concordia method,two samples of zircon,one from a leptynite and anohter from a amphibolites within the khondalite,have been dated at 2 427±42 Ma(2σ)and 2 031±4 Ma(2σ)respectively. Based on field investigation and petrology of metamorpic rock, the main frameword of geologic evolution for the Kongling complex may could be reconstructed as follow :at the Sm_Nd age of 3 250° to 3 150° Ma represented the eruption and emplacement age of protolithic basalt and trondhjemite,which were metamorphosed to amphibolites and grey gneisse,about 2 900 to 2 800 Ma ago (Liu,1987;Li and others,1987;Fu and others,1993). The zircon U_Pb ages of 2 450 Ma and 2 000 Ma are the maximun age and minimun age for the khondalite series respectively. The Kongling complex were transformed to a part of the basement block of the Yangtze platform. about 1 800 Ma ago (Jiang,1986;Zheng and others,1993). |
| MA Da-shuan,LI Zhi-chang,XIAO Zhi-fa.1997.The Constitute,Geochronology and Geologic Evolution of the Kongling Complex, Western Hubei[J].Acta Geoscientica Sinica,18(3):233-241. |
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