新疆乌仑古－斋桑泊构造带晚古生代花岗岩类的稀土元素分布模式

REE DISTRIBUTION PATTERNS OF LATE PALAEOZOIC GRANITOIDS ALONG WULUNGU-ZHAISANGBO TECTONIC BELT,NORTHERN XINJIANG UYGUR AUTONOMOUS REGION

本文选择新疆北部乌仑古－斋桑泊构造带上６个有代表性的花岗岩体，系统进行了岩体地质、显微岩相学、主量元素与稀土元素地球化学研究．根据岩石副矿物类型与主要造岩矿物组成解释了各种岩石类型的稀土配分，根据主量元素－稀土元素相关性闸明了稀土元素在结晶分异过程中的分镏，按照两阶段、不同结晶分异程度模型对各种岩石类型的稀土配分进行了定量模拟；根据不同岩石类型的时空分布及其与构造环境的对应关系探讨了它们的成因。最后，对碱性花岗岩的成因提出了新的解释。

Six representative granitoid plutons are selected along Wulungu-Zhaisangbo tectonic belt,northern Xinjiang Uygur Autonomous Region,on which a systematic investigation are made in their geology,micropetrography,petrochemistry and REE geochemistry.On grounds of accessory types and main rock-forming mineral components, REE distribution patterns in three rock types are explained;REE fractionation during crystal fractionation is expounded based on major element-REE correlation; REE distribution patterns are modelled in the three rock types using geologic, petrologic and micropetrographic constraints; their petrogenesis are approached in the light of the time-spatial correspondence between granitoid plutons and tectonic settings. Finally,a new hypothesis is suggested about genesis of the alkali-granite.