Abstract: Mesoproterozoic mafic dyke swarms are extensively developed in the Western Shandong, the east of the North China Craton, which intruded the Early Precambrian crystal basement. The dorminant orientation of these mafic dykes is nearly N-S trending. The mafic dyke swarms in the Western Shandong belong to LREE enrichment magmatic rocks, and are formed in a continental rift environment according to petrology and geochemistry of these mafic dykes. The flow structures and geometry evidences of the dykes indicatethat the magma source of these dykes intruded the pre-existingtensional rupture . The dyke swarms in the Western Shandong intruded from North to South. Angles between the long axis orientations of magnetic fabric textures and the middle line of dykes suggest that the flow direction of these dykes is from North to South. Further it indicate that the dykes intruded fromNorth to South. These flow structures, geochemistry and magnetic fabric textures suggest that magma come from enriched mantle magma source beneath the Yanliao-Zhongtiao aulacogens based on space-time relationship between the mafic dyke swarms and Yanliao-Zhongtiao aulacogens.

Key words: mafic dyke swarms, Yanliao-Zhongtiao aulacogens, magnetic fabric, flowstructure, emplacement mechanism

摘要： 在华北克拉通东部鲁西地区广泛发育大规模的中元古代基性岩墙群, 侵位于早前寒武纪结晶基底内, 以近南北走向为主。通过岩墙群的岩石和地球化学特征分析, 认为鲁西地区岩墙群属于轻稀土略富集型, 岩墙群的岩浆源自富集型地幔, 形成于大陆裂谷环境。岩墙群的构造形态和流动构造表明鲁西基性岩墙群是基性岩浆侵位到先存的张性破裂中的产物, 岩墙自北部向南部侵入。磁组构的最大长轴方向与岩墙中线的夹角指示岩墙流动方向为自北向南, 进一步说明鲁西岩墙群是向南侵位的。另外, 结合鲁西岩墙群与燕辽拗拉谷的时空关系分析, 鲁西岩墙群很可能是来自中元古代燕辽-中条拗拉谷底部富集地幔型岩浆从北向南侵位到先存破裂中形成的。

关键词: 基性岩墙群, 燕辽-中条拗拉谷, 磁组构, 流动构造, 侵位机制