鲁西前寒武纪基性岩墙群

The Precambrian Basic Dyke Swarms in the Western Shandong Province

鲁西地区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,未变形未变质,以北北西向和近南北向为主,是鲁西前寒武纪最引人注目的一种伸展构造标志。鲁西基性岩墙群属于板内大陆裂谷拉斑玄武岩系列,与板内大陆裂谷活动密切相关,代表一种非造山岩浆活动。该岩墙群富集大离子亲石元素(L IL E) ,略亏损高场强元素(HFSE) ,比较富集Cr、Ni,明显亏损Th。稀土元素配分模式为轻稀土略富集的右倾曲线。鲁西基性岩墙群的微量元素和稀土元素特征反映源区为略富集的地幔。从时空分布特征、构造特征、岩石化学相关性、岩浆源区和古构造应力场分析,鲁西基性岩墙群与燕辽—中条拗拉槽系有一定的成生联系。

A lot of Meso-Proterozoic undeformed and unmetamorphic NW-trending or N-trending mafic dyke swarms develop in the western Shandong, which are conspicuous extensional structures emplacing into Early Precambrian crystal basement. The mafic dyke swarms in the western Shandong are an unorogenic igneous activity as the tholeiite series basalt in the intraplate continental rift environment relative to the continental rifting. The dyke swarms are enriched in LILE, relatively depleted in HFSE, enriched in Cr and Ni and intensively depleted in tholeiite. The mode of REE with enriched LREE is right-dip curve. The trace elements and rare earth elements show that the magma source of the mafic dyke swarms in the western Shandong are from enriched mantle.The mafic dyke swarms in the western Shandong is with the original relation to the Yanliao—Zhongtiao aulacaogens based on the distribution, structural character, geochemistry,magma sources and paleotectonic stress field.