Seminar

Luminescence dating method has great potential in the development of low temperature thermochronology, due to its low equivalent closure temperatures of 35-80 °C. It can determine the instantaneous denudation rate and true uplift rate, which is faster than the regional exhumation rate, especially for the last 1 million years.

The luminescence signal is a result of the competing effects between the trapping of electrons induced by irradiation and the decay of trapped electrons by heating. The dimensionless luminescence signals are evaluated by the equivalent dose (De). The De value corresponds to the apparent age, which is the time elapsed from the equivalent closure temperature to the present. Numerical simulation indicates that the equivalent closure temperature is dependent on the activation energy E and frequency factor s of electron traps, and the cooling rate η.

The Fugong valley of the Nujiang River and the Longyangxia Gorge of the Yellow River were selected to apply the luminescence dating method to qualify the uplift and river incision processes in the eastern margin of the Tibetan Plateau, China. The MAR-TL protocol was used in the measurement of De values. Quartz grains were extracted from twenty samples collected at different elevations on the valley slope. The apparent age results indicate an accelerated incision from 0.4 mm/yr at 263 ka to 18.8 mm/yr at 8 ka. This acceleration increased dramatically since 24 ka. From 263 ka to the present, the valley had been incised ~1042 m. The equivalent closure temperature based on depth of incision is 41-46 °C. This was consistent with a 46 °C closure temperature calculated from a numerical simulation with a incision rate of 0.4 mm/yr (0.01-0.012 °C/ka).