Acta Petrologica et Mineralogica

Zircon is a common accessory mineral in magmatic rocks, sedimentary rocks and metamorphic rocks. Due to its characteristics of high Th and U, zircon has become one of the ideal minerals in the study of geochronology. The principle of the microscopic laser Raman spectroscopy zircon dating method is that the spontaneous α decay of U and Th atoms in zircon causes damage to their own crystal lattice.The accumulation of lattice damage in zircon is positively correlated with the time, and also is correlated with the full width at half maximum Γ of zircon Raman spectrum. The cumulative radiation damage of zircon can be calculated by measuring the full width at half maximum of zircon characteristic peaks with zircon micro laser Raman spectrometer. Thus, the cumulative time of radiation damage can be calculated. Zircon radiation damage dating has the advantages of the high spatial resolution, simple sample preparation and testing methods. However, this method is also subject to various influencing factors, such as the heterogeneity of zircon structure, the rate of thermal annealing, the recrystallization of zircon and radiation damage saturation, all of which would affect the final dating results. The establishment of micro-laser Raman spectroscopy zircon dating method could help to determine the source area of detrital zircon, to reveal the thermal evolution history of rock mass and to identify the later metamorphic thermal events experienced by the inherited zircon. This paper introduces the basic principle, calculation process and age influencing factors of micro-laser Raman spectroscopy zircon dating method. This method is applied for the study of zircon chronology in the metapelites of the Sumdo high pressure metamorphic belt. It provides a new technical method for the zircon chronology.

zircon; microlaser Raman spectroscopy; radiation damage dating; full width at half maximum; low temperature thermochronology