MEASUREMENT PROCEDURE OF SINGLE-GRAIN APATITE(U-Th)/He DATING AND ITS VALIDATION BY DURANGO APATITE STANDARD |
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| Authors: | WANG Ying ZHENG De-wen WU Ying LI You-juan WANG Yi-zhou |
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| Affiliation: | State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China |
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| Abstract: | (U-Th)/He isotopic dating has been developed very quickly in recent years, due to the recognition that the thermal history of rock at low temperature can be effective revealed by such dating method. In particular, He closure temperature in apatite (40~80℃) is very low, so apatite (U-Th)/He ages can reflect the thermal history information of the low-temperature stage, and have a good application prospect in the field of low-temperature thermal chronology. However, because of many influence factors and complicated measurement procedures, the development of apatite He dating in China remains in its early stage. In this study, a measurement procedure was established at the (U-Th)/He dating laboratory of Institute of Geology, China Earthquake Administration. We measured the daughter isotopic helium by diode laser heating four batches of a total seventy-five grains of Durango apatite in an Alphachron helium mass spectrometry system. Then the apatite grains were dissolved to precisely measure the concentration of parent nuclides (U, Th)using the solution isotope dilution method through an automatic sampling ICP-MS (Agilent 7900). Results show that the Th/U values of Durango apatite grains were in the range of 17.23 to 23.60, while all the 75ages were in the range of 28.61 to 34.51Ma with an average of (31.71±1.55)Ma (1σ), which are consistent with the international calibrated ages. |
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| Keywords: | (U-Th)/He dating laser heating isotope dilution method Durango apatite |
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