Basic procedures of optically stimulated luminescence (OSL) dating
2013, 32 (5):
Since its development in the 1980s, optically stimulated luminescence(OSL) dating has been improved significantly. Even though the error is larger(normally 5%~10%), it has obvious advantageous over radiocarbon dating: larger dating range from decadal up to ~700 ka, abundant dating materials(quartz or feldspars), dating directly the sediment, etc. The purpose of the paper is to introduce the method to those geoscientists who intend to use OSL dating for chronological control so that the sampling in the field will satisfy OSL chronologists. We describe the procedures of OSL dating in the luminescence dating laboratory of Qinghai Institute of Salt Lakes, CAS, including sampling, pretreatment, equivalent dose (De) and dose rate determination. We make some suggestions for OSL sampling from strata or drilling cores. In our laboratory we combine the single aliquot regenerative-dose(SAR) and standardised growth curve(SGC) techniques together for De determination, which we call SAR-SGC method with the advantage of reducing machine occupation time for at least 60% compared to that of the SAR method. The abstract of pure quartz of middle grains (38~63 μm) using fluorocilicic acid (H2SiF6) could be much easier and simpler compared to that of coarse grains(90~120 μm) and fine grains(4~ 11 μm), without the use of dangerous hydrofluoric acid(HF). Our systematic investigations on the use of SAR-SGC method for different sediments(aeolian, lacustrine, marine, and glacial, etc.) have shown that the method is valid, even though some factors may result in complexity, e.g. the contamination of heavy minerals and feldspars, the thermal history of quartz grains, etc. Since 2008, we have been applying, with success, the SAR-SGC method to dating loess, desert, lacustrine, ocean, glacial, earthquake, and archaeological site sediments, etc.
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