Application of zircon U-Pb dating of volcanic ash to dating of sedimentary rock

This paper has summarized the significance of dating of sedimentary rock, and introduced the application of volcanic ash zircon U-Pb dating method to dating of sedimentary rocks. Specifically, it has summarized previous studies on the distribution of volcanic event layers, identification of volcanic interlayers, differentiation of volcanic tuff zircons and application examples so as to provide experience for geoscientists in the application of volcanic zircon U-Pb dating. Compared to traditional K-Ar/Ar-Ar and Rb-Sr dating techniques for diagenetic minerals, volcanic ash zircon U-Pb dating has a significant advantage in dating of sedimentary rocks. Volcanic ash interlayer is widespread and isochronous, and zircon U-Pb isotopic system is robust and not easily disturbed. Therefore, volcanic ash zircon U-Pb dating is the first choice for high precision dating of sedimentary rocks. Dating of sedimentary rocks involves field observation, sample collection, indoor petrographic observation, geochronological analysis and age interpretation. Of these, identification of volcanic ash interlayer is the most important despite difficulty. It is necessary to clarify different types of volcanic interlayer and understand the distribution of sedimentary layers of volcanic events. Based on this, field observations and indoor study can be used to further distinguish volcanic interlayers and identify them accurately. In addition, dating of volcanic tuff zircons requires the distinction between volcanic ash zircons, detrital zircons, inherited zircons and xenocrystal zircons, which can be distinguished by mineral morphology and mineral chemistry.