单片再生剂量法测定全新世黄土等效剂量预热条件的研究

A study on pre-heat conditions in equivalent-dose estimation of Holocene loess using single-aliquot regenerative-dose (SAR) protocol

本文通过对双程序单片再生剂量法(Double-SAR)即同时测红外释光(IRSL)和红外之后的蓝光释光(Post-IR OSL)中普遍采用的几种预热温度和cut-heat温度进行了不同组合,然后测定了全新世黄土样品的等效剂量。测定结果表明:等效剂量对预热温度有一定程度的依赖性,而对cut-heat温度的依赖性显得更加明显,一般随cut-heat温度的升高而增大;同时在200—300℃的预热温度范围内,200—240℃的cut-heat温度下测定的等效剂量出现了一个显著坪区,且红外释光和红外之后的蓝光释光测得的结果最为接近。红外释光和红外之后的蓝光释光在以上预热温度和cut-heat温度条件下光释光信号的感量变化方向一致、变幅较小可能是测得的等效剂量较为一致的主要原因。这说明在200—300℃的预热温度范围内,200—240℃的cut-heat温度对于测定年轻的全新世黄土样品是较为可靠的。

Through various arrangements of pre-heat and cut-heat temperatures in the equivalent-dose estimation of Holocene loess using a Double-SAR dating protocol, the paper estimated the equivalent-doses from several loess samples by application of IRSL and Post-IR OSL signals, respectively. The measured results present that the equivalent-dose depends on the heat temperature, especially depends on the cut-heat temperature, showing the equivalent-dose increases with the cut-heat temperature; a plateau of equivalent-dose appears at the 200-300℃ preheat temperatures and the 200-240℃ cut-heat temperatures, furthermore, the equivalent-doses estimated by IRSL and Post-IR OSL signals respectively are close to each other, which resulted from the similar sensitivity change directions of optical stimulated signals and their smaller change ranges in the measurement cycles using the various temperatures of pre-heat and cut-heat. This suggests that the 20（0-300℃ pre-heat temperatures and the 200-240℃ cut-heat temperatures are fit for dating young Holocene loess samples.