吉林南部原老岭群珍珠门组大理岩稀土地球化学

REE Geochemistry of Marbles of the Zhenzhumen Formation of the Laoling Group in Southern Jilin Province

吉林南部早中元古宙老岭群珍珠门组镁质大理岩稀土地球化学特征可以划分为 2种 ,分别发育于I、II分布区。I分布区稀土总量相对较低 ,稀土分异差 ,曲线平坦 ;II分布区稀土总量相对较高 ,稀土分异明显 ,曲线右倾。各区稀土特征的差别反映出来源和形成时大地构造环境的差别。大地构造环境I分布区为与深大断裂有关的拗拉谷 ,II分布区为具有火山活动的大陆裂谷。珍珠门组不具有地层意义 ,应当解体。

REE geochemical characteristics of the marbles of the Zhenzhumen Formation can be divided into two kinds. The first is distributed in AreaⅠand the second in Area II. The REE geochemistry in Area I is characterized by relatively low REE content, no fractionation and flat REE pattern, whereas that in Area II by comparatively high REE content, strong fractionation and right-oblique REE pattern. The difference in REE characteristics reflects different sources of REE and different geotectonic environments. Area I is an aulacogen related to deep faults, while Area II is a continental rift characterized by volcanic activity. The Zhenzhumen Formation has no stratigraphic significance, and hence should be disintegrated.