第四纪沉积物光释光测年中等效剂量测定方法的对比研究

Optically stimulated luminescence dating of Quaternary sediments: A comparison using different equivalent dose determination methods

准确地测定碎屑矿物沉积后吸收的等效剂量是第四纪沉积物释光测年中最关键的一环。用光释光测年技术对几个全新世坡积物、古土壤和黄土等样品中的石英、长石等碎屑矿物进行了测定等效剂量的对比研究。初步结果表明，对于光释光测年，所有样品用再生释光法和澳大利亚滑移法获得的结果均与１４ Ｃ 测年结果或已知年龄相吻合； 部分晒退法只有在光晒退时间适度，且释光强度与剂量呈线性响应时可获得可靠结果，但误差较大；附加剂量法和残留释光法受到多种因素的影响，测定的等效剂量通常偏大。实验还表明，可用绿光释光和红外释光两种不同的光释光测年技术对同一样品测年值进行自检。

It is a key process to precisely measure the post depositonal accumulated absorbed dose (or equivalent dose, Deq) of debris minerals in sediments for OSL methods dating the last exposure to sunlight. A variety of methods for calculating the Deq of a sample were introduced by Wintle and Huntley in 1980. These methods have been developed and subsequently refined since then, and can be divided into five approaches: additive dose, total bleach, regeneration, partial bleach and Australian slide. However, there has never been widespread agreement as to which of these approaches is the most appropriate. Several young (t<10 000 a) known age material deposited under known conditions, such as loess, paleosoil, and talus, were selected. Their Deq values were obtained using different approaches in order to determine the best method for these young sediments. The results indicate that the regeneration and Australian slide methods have been shown to yield the best results in general. The partial bleach technique, when properly applied (with proper partial bleaching time and linear growth curve), seems to be reliable with rather large error. The additive dose and total bleach methods seem to be unreliable and usually yield misleadingly old ages. For sample 97049 and 97050 containing both quartz and feldspar, the same aliquots were first stimulated using infrared emitting diodes with peak emission wavelengths of 880 nm, and then were stimulated using green light with peak emission wavelengths of 514 nm. The results of IRSL and GLSL dating are consistent very well. This maybe indicate that the results of OSL dating can be self tested using different stimulated wavelengths for the same sample.