第七届青年地学论坛

The ²³⁰Th dating (²³⁸U-²³⁴U-²³⁰Th dating method) has become one of the most important dating methods for Quaternary research. However, the ²³⁰Th/²³²Th ratio of 4.4±2.2ⅹ10^-6 is widely used for age correction in ²³⁰Th dating method. Here, we collected active speleothems with exactly known age and zero-year-old calcium carbonate from caves and dated them by ²³⁰Th dating. Our data indicated that the initial ²³⁰Th/²³²Th ratio can be one order of magnitude higher than the ratio of 4.4±2.2×10^-6. High initial ²³⁰Th/²³²Th ratio may result in false and comparatively old calculated age than the real age of young samples with low ²³⁸U concentration. So, the accurate initial ²³⁰Th/²³²Th ratio of active speleothem deposited in the same cave, instead of the general initial ²³⁰Th/²³²Th ratio, is essential for the precise dating of young speleothem samples of low ²³⁸U concentration. Finally, we proposed a procedure to correlate modern observation and speleothem based paleoclimate reconstruction, on the basis of precise ²³⁰Th age which corrected by the true initial ²³⁰Th/²³²Th ratio.
 

Known Age Carbonate,Zero-Age Carbonate,initial 230Th/232Th,230Th dating,Paleoclimate reconstruction