Use of ion beam techniques to characterize lead diffusion in minerals. Final report

摘要

The characterization of diffusion of lead and other trace elements in certain mineral phases has great significance in reconstructing the thermal history of the earth's crust. Such studies permit better interpretation of ''ages'' obtained from isotopic dating. This study uses ion implantation to introduce lead into the minerals apatite and zircon. Diffusion profiles are obtained using Rutherford backscattering (RBS) and the results fit with a model to determine D. Results for apatite over the temperature range 600--900(degree)C show agreement with earlier results obtained traditional geologic techniques. This suggests that radiation damage induced by ion implantation has little effect on diffusion in this case. This approach is both simple and useful in studying diffusion over a temperature range of geologic interest without inordinate annealing times. 17 refs., 5 figs.