青藏东北部若尔盖高原rn全新世泥炭沉积年代学研究

摘要

用泥炭纹泥计年与14C测年相结合的新方法，首次在青藏高原东北部的若尔盖高原建立了系列完整、可信度佳和年尺度的高分辨率更新世末及全新世泥炭沉积年代谱，时间跨度为13 655年至现在；阐明了若尔盖高原不同类型全新世泥炭沉积的时序和空间分异规律；从沉积学上证实了各期仙女木事件的存在和发生时间；划定全新世大暖期为距今9 500～2 000年，是泥炭沉积高速期；计算了泥炭沉积率。上述结果对青藏高原也有一定代表意义。%Qinghai-Tibet Plateau is a unique and special region on environ mental change,the famous wetland of Zorge Plateau is in northeast Qinghai-Tibet an Plateau and covers 4 605.28 square kilometers.In the wetland,peat was widely piled in the wide valleys and abundant information about environmental chan ge was contained in it,which is very valuable for investigating the globally env ironm ental change.rn　　Erecting a correct time reference frame of Holocene is the precondi tion to make use of great environmental information.Existed time re ference fra me of Holocene was established based on the 14　C data,and it is limited a nd has Shortcomings.So,it is necessary to look for a method that is more reliable and can emend result of 14　C age.Authors discovered peat varve s tr ucture in peat layers of Zorge Plateau wetland,which could be used as a new meth od combinig 14　C for determining Holocene age.And it is posible that the resolution come up to standard of year.rn　　The paper,which is based on age dates that were made just from mine Ⅱ of Hongyu an Peat Site,found an age table of Holocene peat deposition.The table is a more complete system and has higher believable and higher resolution.In addit ion ,the age dates of some important peatland in Zorge Plateau except the region of Hongyaun were published systematically,and then the age sequence of peat in Zorg e Plateau was presented in the paper.rn　　These results indicated that the Latest mire mud of the Zorge Plateau formed in above 12 000 yrBP and the deposition of peat started in 11 500 yrBP.It was alse closed of a violently falling temp e rature, Younge Dryas ,appeared in 11 500～12 111yrBP.The Holocene megather mal was formed from 9 500 yrBP to 2 000 yrBP,which is a period of faster peat d eposition.Before 9 500 yrBP and after 2 000 yrBP of Holocene,peat depositio n slowed. The slowest period of peat deposition has appeared in modern times.Under the eff ec t of difference of environment,peat age of deposition has big difference in the plateau.Generally,the high mountainous regions are later than the wide valley, and the latter was dominant in middle Holocene.