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 6 5 5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 95 0 0～ 2 0 0 0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.
Abstract:
Qinghai-Tibet Plateau is a unigue and speciai region on environmental change,the famous wetland of Zorge Plateau is in northeast Oinghai-Tlbetan Piateau and covers 4 605. 28 sguare kilometers. In the wetland,peat was wideiy piled in the wide valleys and abundant information about environmental change was contained in it,which is very valuabie for investigating the globally environmental change. Erecting a correct time reference frame of Holocene is the precondition to make use of great environmental information. Existed time reference frame of Holocene was established based on the 14C data,and it is iimited and has Shortcomings.So,it is necessary to look for a method that is more reliable and can emend result of 14C age.Authors discovered peat varve structure in peat layers of Zorge Piateau wetiand,which couid be used as a new method combinig 14C for determining Holocene age.And it is posible that the resolution come up to standard of year. The paper,which is based on age dates that were made just from mine Ⅱ of Hongyuan Peat Site,found an age tabie of Holocene peat deposition. The tabie is a more complete system and has higher believabie and higher resolution. In addition,the age dates of some important peatland in Zorge Plateau except the region of Hongyaun were published systematically,and then the age seguence of peat in Zorge Plateau was presented in the paper. 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 vlolently falling temperature,Younge Dryas ,appeared in 11 500 ~ 12111yrBP. The Holocene megathermal was formed from 9 500 yrBP to 2 000 yrBP,which is a period of faster peat deposition. Before 9 500 yrBP and after 2 000 yrBP of Holocene,peat deposition siowed. The slowest period of peat deposition has appeared in modern times. Under the effect 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.
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