摘要
通过对糜地湾剖面红外释光测年结果与 1 4 C测年结果 (校正年代 )比较 ,认为红外释光测年方法应用于沙漠黄土边界带湖相沉积物的年代测定可取得理想结果。介绍了适合红外释光测年的粗颗粒钾长石矿物的分离 ,对粗颗粒钾长石红外释光信号的光晒退、残留信号和回授等性质作了初步研究 ,对测量等效剂量的附加剂量法和再生法进行了比较 。
It has been established that the Optically Stimulated Luminescence (OSL)dating can date the aeolian sediments from the loess and desert transitional zone in China.However,the OSL dating of lacustrine organic rich sediments in this area has not been reported.Being sensitive to the changes in monsoon climate,the loess and desert transitional zone in China is an ideal region for the study of past global changes.The lacustrine sediments in this area can provide high resolution section.The attempt to date the lacustrine sediments is of significance for the past global change study.The Midiwan section is situated in the transitional zone with a thickness of 13 8 m spanning the time after the last deglaciation.It consists of silt,peat and aeolian sand sediments,and has been well studied on the records of past climatic changes during the Holocene. The main purpose of the present work is to date the lacustrine samples from Midiwan section,which has been well dated by 14 C dating on peat,using the Infrared Stimulated Luminescence (IRSL).The K rich feldspar(90～125 μm)is extracted for IRSL dating using heavy liquid separation.The solar lamp bleaching of IRSL signal of K feldspar has been examined,the recuperation after preheating investigated.The IRSL signal is reduced to less than 1% after 20 min bleaching.The recuperation is negligible after 5 min at 220℃ preheating,which is encouraging in IRSL dating of samples of decadal scale. The additive and regeneration methods are applied to the determination of equivalent dose.The additive ages are in good agreement with the 14 C ages.The laboratory bleaching causes sensitivity changes resulting in the underestimation of the regeneration ages.It is concluded that the IRSL dating is a suitable method to date the lacustrine sediments from the loess and desert transitional zone in China.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2001年第1期75-80,共6页
Marine Geology & Quaternary Geology
基金
中国科学院重大项目 !(KZ915 -A1-4 0 2 )
国家自然科学基金资助项目 !(49894170 )
