不同地区石英ESR Al心自然光晒退

Sun bleaching of aluminum center of quartz in cities of different latitudes in China

本文研究了两种石英样品的Al心ESR信号的自然光晒退行为，样品分别为采自华山的花岗岩和海南三亚亚龙湾海滩沙。在海拔50-3600m的四个地区（北京、银川、格尔木、拉萨）进行晒退试验。提纯后的石英用钴源辐照200Gy，再在阳光下晒退，照度≥2×10^4 1x，最长晒退时间为500h。结果表明，在上述四个地区两种石英Al心ESR信号的晒退趋势基本一致，自然光对石英Al可以晒退，但不能完全回零；100h内，光晒退较快，200h后趋于稳定；不同来源的样品，其晒退结果差别较大，采自海滨沙的石英Al心的晒退率仅约20％，而采自岩样的石英晒退率约40％-50％。

As aluminum center cannot be completely bleached with a plateau value in the ESR spectra, the residual dose must be subtracted from the equivalent dose in order to obtain the real paleo-dose. Two types of quartz samples extracted from granite and littoral sand were exposed directly to sun-light at four cities of different latitudes in China, in an attempt to study the latitude effect on bleaching results of the Al center ESR signal and to see the dependence of quartz origins. No significant difference was found in samples bleached at different latitudes, but significant difference was found in samples of different sources. For quartz from granite, the bleaching rate is 40% to 50%, while only about 20% for littoral sand.