辽西义县旋回火山岩的稀土元素特征

义县火山旋回可分为4个亚旋回。从早期至晚期,义县旋回火山岩逐渐由基性向中基性、中性和酸性演化。义县旋回火山岩稀土总量较高,稀土分布模式呈右倾型,轻稀土分馏作用高于重稀土的分馏作用,为轻稀土富集型,总体显示弱负铕异常、弱的正铈异常。稀土元素具有陆内火山岩的基本特征。成因分析表明:义县旋回火山岩的形成,受地幔热流和壳幔物质的再循环制约,火山岩的成因以部分熔融为主。

Rare earth element characteristics of volcanic rocks from Yixian formation of Western Liaoning

Volcanic rocks of mesozoic were widely distributed in Western Liaoning province.Yixian volcanic Cycle of early Cretaceous is divided into four subcycles.From early to late, the magma of Yixian volcanic cycle evolved gradually from basic, inter mediate-basic and intermediate to acidic.The ∑REE of volcanic rocks of Yixian volcanic cycle is high and rich in LREE.The spider patterns are the right-incline and there is a slight low Eunegative abnormality and low Ce postive abnormality.REE characteristics show that volcanic rocks of Yixian volcanic cycle were generated in responsing to lithosphere extension in the continent intraplate orogenic belt.The lithogenesis take partial melting as a major part.