关键词: 第四纪火山岩, K-Ar, ⁴⁰Ar/³⁹Ar, 高精度定年, 误差分析, 惰性气体质谱, 自动化

Abstract: As the requirement of study on paleontology,paleoclimate,magma process,volcanic disasters and paleomagnetism,scientists pay more attention to the young volcanic rocks dating in recent years.In this paper we review the achievements of the ⁴⁰Ar/³⁹Ar dating on young volcanic rocks during the last 10 years,and compare the limitations and strengths of K-Ar,conventional ⁴⁰Ar/³⁹Ar and laser ⁴⁰Ar/³⁹Ar dating methods.As the development of ⁴⁰Ar/³⁹Ar dating relies on the technique improvement,we discuss the influence of the new noble gas mass spectrometer and the full automation of the dating system on the young volcanic dating.Neutron irradiation and flux monitor standard sample are important to get accurate age,so we talk about the neutron flux gradient of Beijing 49-2 reactor which we usually use for sample irradiation and choose the suitable standard for young volcanic sample.We also discuss the analytical error and its sources in detail according to the experience in young volcanic rocks dating.The analytical precision of ³⁶Ar,system blank and mass discrimination are the 3 main internal factors influencing the precise dating of young volcanic rocks.We give two graphs to illustrate the fact and some suggestions to solve this problem.At last,we talk about the problems of ⁴⁰Ar/³⁹Ar dating on young volcanic rocks and what we should do to solve these problems in the future.The improvement of accuracy and precision of ⁴⁰Ar/³⁹Ar dating of young volcanic rocks will make it a more widely used technique and play a more important role in Quaternary geosciences.

Key words: Quaternary volcanic rocks, K-Ar dating, ⁴⁰Ar/³⁹Ar dating, error analysis, noble gas mass spectrometer, full automation