北祁连山西段中元古代蛇绿岩的发现及其地质意义

Discovery of Middle Proterozoic Ophiolite in the West Part of North Qilian Mountains and Its Geological Significance

北祁连山西段中元古代蛇绿岩的发现及其地质意义张招崇（中国地质科学院地质研究所，北京１０００３７）毛景文杨建民左国朝吴茂炳（中国地质科学院矿床地质研究所，北京１０００３７）（甘肃省地矿局地质科学研究所，兰州７３００００）关键词中元古代蛇绿岩北祁连山西段...

The Aoyougou ophiolite is situated in the Qiqing village of Sunan County,Gansu Province.The single zircon dating for diabase in the Aoyougou ophiolite showed that the Aoyougou ophiolite,the oldest ophiolite in China was formed in the early stage of Middle Proterozoic.All rock types of Aoyougou ophiolite were characterized by enrichment in LREE and LILE.The geochemical characteristies of basaltic lava in the ophiolite were similar with P MORB,indicating that they originated from the enrichment mantle resembling the source of OIB.The measured age of diabase of the Aoyougou ophiolite showed that there existed a trench arc basin system in the west section of North Qilian Mountains at the early period of Middle Proterozoic