Application of long time artificial optical bleaching of the E1’ centre to sediment ESR dating

Three quartz samples extracted from different origins were collected for ESR evaluation to appreciate the optical bleaching characteristics of the ’ centre in a long time scale. After exposure of about 400 hours to artificial sunlight, the ’ centre were bleached to a steady increasing level, about 2.5 times of its natural level, and the increase level also exhibit a small variability among different sample origins. The constant increasing level provide a significantly evidence for the potential use of the natural signal intensities of quartz ’ centre in tracing sediment provenance. The results show that the signal intensity of ’ centre increased within beginning 84 h and decreased after 202 h as previous researches have partly predicted. After long time exposed to sunlight, there is no correlation between irradiated samples’ dose rate and its ’ centre ESR signal intensity. Thus, no new convenient indication shed light on the possible use of the ’ centre for ESR sediment dating.