通过紫金山岩体的地球化学分析,系统探讨了岩体的物质组成及其岩浆成分演化特征和可能的动力学演化环境,为鄂尔多斯盆地东部深部岩浆活动-热力作用提供重要信息。紫金山岩体的地球化学特征表明:岩体具有全碱含量较高((K2O+Na2O)=8.64%～16.09%),贫SiO2,根据碱度率图解,判别该岩体属于偏碱性-碱性系列;稀土含量较高,轻稀土富集,轻重稀土元素发生了不同程度的分馏,Eu异常现象不明显。富集大离子亲石元素,而亏损Nb,Ta,Ti等高场强元素。在此基础之上,通过主量元素的氧化物变异图解分析,认为紫金山岩体可能来源于深部相近或统一的原始岩浆源区,在其上侵演化过程中形成了高钾-低钙的碱性系列岩石和低钾-高钙的碱性-偏碱性系列岩石。结合相关判别图解表明,其物质来源至少达到了壳-幔过渡带或其更大的深度层次;构造环境属于板内拉张环境。因此,紫金山岩体所代表的鄂尔多斯盆地燕山晚期的构造热事件是在华北克拉通大规模伸展背景下,深部物质在地壳中浅层或地表作用的结果。 Through the geochemical analysis of the Zijinshan rock mass, the physical composition of the rock mass and the evolution characteristics of the magma component and possible dynamic evolutionary environment are systematically discussed, providing important information for the magmatic activity-thermal action in the eastern Ordos Basin. The geochemical characteristics of the Zijin Mountain rock mass indicate that the rock mass has a high total alkali content (K2O + Na2O = 8.64% ~ 16.09%) and is poor in SiO2. According to the alkalinity rate diagram, Alkaline series; higher REE content, light rare earth enrichment, different degrees of fractionation of light and heavy rare earth elements, Eu anomalous phenomenon is not obvious. Enrichment of large ion lithophile elements, and loss of Nb, Ta, Ti and other high field strength elements. On this basis, the analysis of the oxide variation of major elements shows that the Zijinshan pluton may originate from the original magma source areas which are similar or uniformed in the deep, forming a high potassium-low calcium Alkaline series of rocks and low potassium - high calcium alkaline - alkaline series of rocks. According to the related discrimination diagram, it shows that the material source has at least reached the crust-mantle transitional zone or its deeper depth level; and the tectonic environment belongs to the tension environment inside the plate. Therefore, the tectonic thermal events of the late Yanshanian period in the Ordos Basin, represented by the Zijin Mountain, are the result of the shallow materials acting in the shallow crust or the earth’s surface in the crust under the background of the large-scale extension of the North China Craton.