辽西义县旋回火山岩的稀土元素特征

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

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。

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,intermediatebasic and intermediate to acidicThe ΣREE 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 Eu negative 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