| 北祁连奥陶系地体中蓝片岩、绿片岩岩石矿物化学特征及地质意义 |
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| 引用本文：霍有光,吴汉泉,冯益民.1992.北祁连奥陶系地体中蓝片岩、绿片岩岩石矿物化学特征及地质意义[J].地球学报,13(1):59-70. |
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| 基金项目:国家自然科学基金 |
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| 中文摘要:甘肃肃南县奥陶系构造地体中变质火山岩主要指蓝片岩、绿片岩及熔岩、凝灰岩。岩石化学特征表明,区内这些岩石属同源演化系列,多数为中基性,岩类属大洋拉斑玄武岩系列。与美国舒克桑岩套蓝片岩、绿片岩对比,两者具有相似的岩浆分异趋势,但肃南岩浆初始分异程度较低,相当现代FAMOUS区洋中脊岩石成分范围。进一步可分为LREE亏损组和LREE中等富集组,LREE亏损组也能与舒克桑蓝片岩和绿片岩类比,原岩产出环境为N型洋中脊。从矿物化学特征看,肃南硬柱石、绿纤石蓝闪片岩可与美国Cazadero硬柱石蓝片岩带、绿纤石蓝片岩带 |
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| GEOCHEMICAL CHARACTERISTICS OF ROCKS AND MINERALS OF BLUESCHISTS AND GREENSCHISTS IN ORDOVICIAN TERRANE IN THE NORTHERN QILIAN MOUNTAINS SUNAN COUNTY,GANSU PROVINCE |
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| Abstract:Metavolcanic rocks of Ordovician tectonic terrane mainly make up blu-eschists, greenschists, lavas and tuffs in the Sunan county. Geocbemical characteristics of rocks displays an isosource evolutional system, most of the rocks are basic and intermediate. Their nature belongs to oceanic tholeiitic series. Comparison to bluecchists and greenschists of the Shuksan (Washi-ngto.) indicates that the Sunan samples have similar magmatic differential trend, but the primitive differential level of the Sunan magma is lower, correspond to modern MORB composition of the FAMOUS area (after Owen, 1989) . They are divided into LREE-depleted group and mildly LREE-enri-ched group. Samples of LREE-depleted group are selected for comparison with blueschists and greenschists of the Shuksan, their geological formation setting meaned N-type MORB. According to chemical characteristics of minerals, lawsonites and pumpellyites of the Sunan can be compared with lawsonite zone and pumpellyite zone of the jadeite-glaucophane type facies series in Cazadero (California), high-p metamorphic environment of the Sunan plate movement took place at depths of above 20 km in the underplating subduction zone. |
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