鲁西银山庄地区煌斑岩岩石地球化学特征及其构造环境探讨

Study on Geochemical Characteristics and Tectonic Environment of Lamprophyre in Yinshanzhuang Area in Luxi Uplift

摘要:

鲁西银山庄地区煌斑岩系统研究程度较低，据此，对其开展详细的岩石学、岩石地球化学研究，探讨岩石成因及构造背景。岩石化学组分中SiO2含量为36.91%~47.18%，TiO2含量为0.95%~1.11%，MgO含量为1.13%~4.95%，K2O+Na2O含量为4.37%~6.47%，贫硅富镁，属超基性—基性岩石，为钾玄质碱性煌斑岩，岩石以富集大离子亲石元素和轻稀土元素，亏损高场强元素为特征。煌斑岩应为早白垩世区域岩浆活动的产物，在华北板块构造拉张、岩石圈减薄环境下，俯冲的陆壳扬子下地壳形成的富集岩石圈地幔源区发生部分熔融，形成银山庄煌斑岩岩脉。

Abstract:

The lamprophyre system in Yinshanzhuang area in western Shandong province is poorly studied. Therefore, detailed petrology and petrogeochemistry have been carried out, and the petrogenesis and tectonic setting have been studied. The content of SiO2 is 36.91%~47.18%, TiO2 is 0.95%~1.11%, MgO is 1.13%~4.95%, and K2O+Na2O is 4.37%~6.47%. It is poor silicon and rich magnesium. It belongs to ultrabasic—basic rock and potassium basalt alkaline lamprophyre. The rock is characterized by enrichment of large ion lithophilic elements and light rare earth elements, and depletion of high field strength elements. The lamprophyre is the product of early Cretaceous regional magmatic activity. Under the environment of northern China plate tectonic stretching and lithosphere thinning, the enriched lithospheric mantle source formed in the subducted continental Yangtze crust partially melted and formed Yinshan lamprophyre dike.