Red TL of quartz extracted from Chinese loess: Bleachability and saturation dose

The red TL of quartz has been shown to exhibit a much higher saturation dose than that of the UV emission in quartz, and thus has the potential to considerably extend the dating range. Unlike heated materials, in which the luminescence signal has been completely thermally reset, the quartz red TL from Aeolian sediments accumulates on top of a residual signal left after daylight bleaching. The characteristics of this bleaching process must be investigated before any dating attempts can be made. It is demonstrated in this paper that the red TL of quartz extracted from Chinese loess: (1) bleachable by sunlight, but with high residual level. Up to about 40% of the natural signal remains after bleaching in our sample; all of the broad natural TL peak bleaches simultaneously in sunlight; (2) has significant dose-dependent sensitivity change when laboratory doses beyond 1500 Gy are applied; this sensitivity change cannot be corrected for by a test dose; and (3) has a D0D0 value of ∼550Gy, much larger than that of optically stimulated luminescence (OSL) (∼90Gy) from the same sample.