The ESR dating of Al and Ti centers for the quartz in igneuse rock can give the time when the rock reached the closure temperature. But the use of this method is hindered by two factors: 1) the ESR signals of Al and Ti centers can only be obtained at low temperature(100K); 2) The ESR full-peak spectra are complex . It is difficult to choose the peak for dating. For the reasons given above

little work has been done with Al and Ti centers to date the igneous rocks. In this work

the experiments were done at 100K and in a modulation magnetic field of 5×10 -4 T

and got good results because of the suitable conditions. The spectra were stable and well reproduced. It was easy to choose a peak for dating and to determine the height of the peak. In our sample

the age of Al center and Ti center were 774.7ka and 256.0ka

respectively. The difference between the ages was induced by the fading of sun-light. Experiment had been done by sunlight and ultravoilet exposure. The result was that 50% Al-centers and 27% Ti-centers were left by sunlight

50% Al-centers and 50% Ti-centers were left by ultraviolet exposure.