岩浆弧背景下的高镁安山岩具有与大陆平均地壳相似的成分，其成因对于理解大陆地壳的形成与演化有着十分重要的意义。本申请是在早期预研究和工作积累之上，选择西秦岭早中生代两期高镁安山岩及其共生岩石作为解析对象，拟通过对其进行细致的地质调查、岩相学、矿物学、元素和同位素地球化学以及精确的年代学研究，重点剖析西秦岭高镁安山岩的形成条件、源区组成、岩浆演化的相关细节，查明其岩石成因。然后结合区域地质资料，进一步综合限定其形成的动力学背景。该研究不仅能在利用单矿物原位主量、原位微量和单斜辉石原位Sr同位素探究高镁安山岩的岩石成因方面提供一个重要的研究实例，也为利用火成岩组合（基性岩、高镁和低镁安山岩、闪长岩、埃达克岩等）约束西秦岭早中生代的下覆岩石圈性质和地壳增生机制方面提供重要的岩石学证据。

High-Mg andesites occurred in a magmatic arc background show strikingly similar to the bulk continental crust in terms of compositions, therefore, it is of considerable significance for understanding the genesis of high-Mg andesites to decipher the formation and evolution of the continental crust. According to our preliminary study and former research work, this project mainly focused on the two periods of high-Mg andesites and associated rocks during the Early Mesozoic in West Qinling. Based on the detailed geological survey, petrography, mineralogy, elemental and isotopic geochemistry and precise geochronology, we are aiming to dig and discover the scenario about formation conditions, source compositions, magma evolution process, and finally explore the origin and petrogenesis of these rocks. Combined with the regional literatures, the geodynamic background of these rocks will be further constrained. This project will not only provide an significant case study to probe into the petrogenesis of high-Mg andesites using in situ major and trace elements, as well as in situ Sr isotope, but also offer reliably petrology evidence on the nature of lithosphere beneath West Qinling and mechanism of continental growth during the Early Mesozoic in terms of igneous rock associations (e.g. mafic rocks, high-Mg and Low-Mg andesites, diorite, adakites).