| 小兴安岭西北部奥陶系火山岩形成环境 |
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| 引用本文：余金杰,徐志刚,徐凤山.1996.小兴安岭西北部奥陶系火山岩形成环境[J].地球学报,17(1):54-64. |
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| 中文摘要:本文依据火山岩岩石化学、微量元素和稀土元素地球化学特征，论述了小兴安岭西北部中奥陶统火山岩形成于陆缘弧环境。并且，用板块俯冲机制对其形成机制进行了解释。 |
| 中文关键词:陆缘弧 地球化学标志 板块俯冲 奥陶系火山岩 小兴安岭 |
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| Tectonic Setting of Ordovician Volcanic Rocks in Northwestern Xiaoxing'anling, Heilongjiang Province |
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| Abstract:The Ordovician volcanic rocks,occurring in northwes tern Xiaoxing'anling,Heilongjiang Province,have the following features:1. They generally belong to calc-alkaline seriers on Na2O+K2O+K2O-SiO2 plot and AFM diagram despite strong potassic,silicic and spilite aftemation. They mainly belong to CAB on TiO2-MnO×10- P2O5×10 diagram.2. NMORB-normalized incompatible element distributions of volcanic rocks in this area are similar to that of continental-margin arc Cafe-alkaline series basalt. Their differences are that volcanic rocks in this area have high TI,Ta,Nb, Ce and low Cr. High Th, Ta,Nb contents indicate that the magma was composed of rutile, sphene and zircon that enriched in Th, Ta, Nb, Ce. Low Cr reflects that magma came from pert-melting upper mantle.3. Rare earth element distribution patterns of volcanic rocks are similar to that of island arc cafe-alkaline series basalt. Alternation resulted in ion of Ca2+ and depletion of Uranium.So the authors think that middle Ordovician volcanic rocks were formed in continental-margin arc serring relating to plate subduction. |
| keywords:continental-margin arc geochemical log plate subduction Ordovician volcanic rocks Xiaoxing' anling, |
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