海洋地质与第四纪地质
海洋地質與第四紀地質
해양지질여제사기지질
MARINE GEOLOGY & QUATERNARY GEOLOGY
2001年
1期
75-79
,共5页
赖忠平%张景昭%卢演俦
賴忠平%張景昭%盧縯儔
뢰충평%장경소%로연주
湖相沉积%钾长石红外释光测年%14C年代%晒退实验%回授信号
湖相沉積%鉀長石紅外釋光測年%14C年代%曬退實驗%迴授信號
호상침적%갑장석홍외석광측년%14C년대%쇄퇴실험%회수신호
通过对糜地湾剖面红外释光测年结果与14C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,同时还介绍了中国科学院黄土与第四纪地质国家重点实验室释光测年实验室从样品采集开始到年代值计算的整个测年实验流程。
通過對糜地灣剖麵紅外釋光測年結果與14C測年結果(校正年代)比較,認為紅外釋光測年方法應用于沙漠黃土邊界帶湖相沉積物的年代測定可取得理想結果。介紹瞭適閤紅外釋光測年的粗顆粒鉀長石礦物的分離,對粗顆粒鉀長石紅外釋光信號的光曬退、殘留信號和迴授等性質作瞭初步研究,對測量等效劑量的附加劑量法和再生法進行瞭比較,同時還介紹瞭中國科學院黃土與第四紀地質國傢重點實驗室釋光測年實驗室從樣品採集開始到年代值計算的整箇測年實驗流程。
통과대미지만부면홍외석광측년결과여14C측년결과(교정년대)비교,인위홍외석광측년방법응용우사막황토변계대호상침적물적년대측정가취득이상결과。개소료괄합홍외석광측년적조과립갑장석광물적분리,대조과립갑장석홍외석광신호적광쇄퇴、잔류신호화회수등성질작료초보연구,대측량등효제량적부가제량법화재생법진행료비교,동시환개소료중국과학원황토여제사기지질국가중점실험실석광측년실험실종양품채집개시도년대치계산적정개측년실험류정。
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 14C 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 14C 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.