To study the tectonic background of the Weiboshan area in the eastern part of the Beishan orogenic belt,granite,which is widely developed in this area,was selected as the research object.Through field geological work,zircon U-Pb geochronology,petrology,and geochemistry,the formation age,type,petrogenesis,and tectonic background of the Weiboshan granite were deeply analyzed.The zircon ages are(440.8±0.19)Ma and(155.05±0.37)Ma,indicating that the Weiboshan granite was formed in the Early Silurian and formed a composite granite body in the Jurassic.The samples are named monzonitic granite based on petrological characteristics;geochemical characteristics demonstrate that the genetic type is S-type granite.The rare earth distribution curve and trace element spider diagram are right-leaning,showing the characteristics of island arc magmatic rocks.According to the content characteristics of Yb,Y,Sr and Al2O3,it is determined that two of the samples are adakite.The tectonic-magmatic evolution model of Weiboshan is established:the Xiaohuangshan oceanic basin subducted northward in the Early Silurian,the mantle-derived magma intruded,and the felsic magma moved out to form island arc magmatic rocks.
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