北祁连冷龙岭地区宁缠河花岗岩体的地球化学特征及大地构造意义

宁缠河花岗岩岩体位于北祁连中段,由两阶段侵入体构成,第一阶段侵入体具I型花岗岩特征,第二阶段侵入体为S型花岗岩。微量和稀土元素地球化学特征表明,岩体具有轻稀土富集型的球粒陨石标准化模式,两阶段侵入体形成于不同的构造环境,清阳河单元可能是在弧陆发生软碰撞时,岛弧型岩浆房中富含硅质的残余岩浆,在挤压应力下,快速上升侵入形成,下夹石及上池沟单元形成于同碰撞造山阶段。

GEOCHEMICAL FEATURES OF NINGCHANHE GRANITE BODY AND ITS' TECTONIC SIGNIFICANCE IN LENGLONGLING OF NORTH QILIAN

Ningchanhe granite body which is located at the middle section of north Qilian comprises of intrusive bodies of 2 phases.The body of the first phase occurs with the features of I-type granite,while the other of the second phases with the features S-type granite.The geochemical features of trace and rare elements show that the rock body is the chondrite standard pattern of light-rare-element-rich type,intrusive bodies of 2 periods occurred in the different environments.It is supposed that Qinyanghe Unit maybe occurred during the period when collision of arc continent happened,silicate-rich magma remains in magma chamber of island arc raised rapidly and intruded under the stress of compression,but Shangjiashi Unit and Shangchigou Unit formed in syn-colliding orogenic stage.