| The Holocene was a period that had a close relation with mankind, so it could be very important to bring to light the laws of Holocene climatic variations for understanding nowadays geographic environment and its trend of development. Dating would be particularly important in order to elaborate the characteristic of climatic variations and its regional discrepancy. As there are less such materials in loess as fossil, plants, slag , etc, which could be used for dating, luminescence dating, especially optically stimulated luminescence dating, was extensively applied to aeolian deposits, for its dating materials were minerals, such as quartz and feldspar. Recently, single-aliquot technique has been paid close attention in OSL dating, because of its higher precision, less quantity, as well as normalization is avoided in single-aliquot. Loess is silt-sized aeolian deposit and is mainly composed of quartz and feldspars, its OSL signals can be set to zero by exposure to light. In order to elaborate the applicability of OSL to loess, especially single aliquot regenerative protocol (SAR), involving stimulation of the same disc with an infra-red laser diode followed by blue LEDs to polymineralic fine-grains of loess, such explanations as light bleaching, preheat, anomalous fading, prior-IR exposure were investigated in this paper. For drawing adequate coarse grains from loess, quartz and feldspars, as well as loess, were etched by hydrofluoric acid and fluorosilicic acid. The sequence of ages of Holocene loess in Weihe Rivier Basin has been established by single-aliquot (SAR) and multiple-aliquot using fine-grains and SAR using coarse-grains. The main results are as fellows:1. The bleaching experiment of loess by iodine tungsten lamp and the equivalent dose (De) of loess estimated by SAR from the earth's surface indicate that loess can be easily bleached by sunlight, and OSL is suitable for the dating of loess.2. Equivalent dose estimated by SAR, when each natural or regenerated dose OSL measurement is corrected for changes in sensitivity using the OSL response to a subsequent test dose and the recycling ratio is around 1, implies that sensitivity changes have been properly corrected. The sensitivity corrected zero dose regenerated signal is within 5% of the sensitivity corrected natural signal, implies that the recuperation is negligible. Also, the precision of De estimated by SAR is higher than that estimated by multiple aliquots.3. The experiments of anomalous fading, preheat and the effect of prior-IR exposure on OSL stimulated by blue light in polymineral fine grains, indicate that the post-IR OSL signals do not show detectable fading, and has greater thermal stability. It must be noted here that blue stimulated luminescence from polymineral fine grains presumably originate from both quartz and feldspar grains, and it is thus likely that any blue stimulated signal following an IR exposure in our samples will be richer in quartz OSL in comparison to a pure blue stimulated signal without IR exposure.4. When the quartz fraction was cleaned of feldspar grains by etching in concentrated HF for 40min, more quartz fraction was etched away, and this method may be not suitable for the purity of quartz in loess. As quartz fraction in loess is separated by the tedious process of etching with fluorosilicic acid for 6 days, 20ml 30% fluorosilicic acid per gram, not only the feldspars in loess could be removed completely, but also less quartz could be etched away in loess.5. The OSL dating of 37 samples of loess in Weihe River Basin by SAR and multiple aliquot methods, indicates that SAR protocol appears to be applicable to loess and appropriately correcting for sensitivity changes within the regenerated curves, however, there are major difference between the IRSL and Post-IR OSL De determinations that suggest that sensitivity changes relating to either (or both) Natural signals may not be correctly monitored. While SAR is applied to fine grains of loess, the ages of sample which is youn...
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