干旱区生态环境知识资源中心(Arid): 西藏台错古生物记录的古环境事件及硅藻、介形虫化石新发现

Arid

	西藏台错古生物记录的古环境事件及硅藻、介形虫化石新发现
其他题名	Paleoenvironmental Events Recorded by Palaeontology and Discovery of Fossil Species of Diatom and Coastal in Dahyab Tso, Tibet
	魏乐军 1; 刘建华 2; 李家英 3; 庞其清 4; 童国榜 5
ISSN	0001-5717
出版年	2007
卷号	81 期号:9 页码:1169-1182
中文摘要	在厚度为369 cm的台错TT-1剖面中,共采取连续样品156个,单样平均厚度仅为2.36 cm,使之成为一个理想的进行高分辨率研究的对象.通过对样品的硅藻研究,以及全部样品的孢粉和介形虫化石分析鉴定,本项研究取得了多项创新研究成果.①结合铀系不平衡法获得的准确可靠定年数据,本文重建了西藏台错古湖区自晚更新世晚期以来的古气候、古环境演变.从万年尺度上,台错在＞32.60～26.15 ka BP间的6.45 ka间长期处在潮湿、湿润的环境之中;在26.15～4.50 ka BP的21.65 ka间,气候则以偏干和寒冷为大背景;在4.50 ka BP,沉积记录终断,表明湖泊干枯消失.从百年-千年尺度上,厘定出台错自22.70 ka BP以来,经历了明显的寒冷气候事件8起,湿润气候事件3起,以及气候颤动事件2起,从而更加详尽地描述了台错在18.2 ka中经历的19个古环境、古环境演变阶段.②首次发现了两种硅藻的新化石种--西藏胸隔藻属新种Mastogloia tibetica Li et Wei和西藏桥弯藻属新种Cymbella taicuonensis Li et Zheng.③首次在西藏境内大量发现了Cyprideis torosa(结节正星介)和C. littoralis(滨海正星介).本文为全球气候变化研究及青藏高原的古气候、古环境研究,提供了来自高原内部的全新精细记录和科学依据.
英文摘要	The saline lake-Dahyab Tso (Tai Cuo, Tso means lake in Tibetan located in the northern Tibetan Plateau is chosen as our study object. The environment in Dahyab Tso is very harsh, without any human pollution. Field work was carried out in 2001. Sampling was conducted on the 369 cm Profile TT-1 in a high consistency, and the average thickness of each sample has been limited to 2.36 cm. It is so come to be a perfect object to do the high-resolution research. While the study in palynology and ostracods with whole 156 samples in profile TT-1, and in diatom, it is summarized the achievements as follows.(1) Based on the credible dating results by Uranium-series chronology combined with the total-sample-dissolution isochron techniques, this research established the paleoclimate and paleoenvironment of Dahyab Tso (Tai Cuo) in Tibet since the Late Pleistocene. By the ten-thousand timescales, the two quite different changing stages of climate condition were recognized in the Dahyab Tso area: from >32.6 ka BP to 26.15 ka BP, the climate background with a duration of 6.45 ka was generally humid and warm; and then, from 26.15 ka BP to 4.50 ka BP, the climate was generally in a slightly dry and cold big background with a duration of 21.65 ka; After 4.50 ka BP, as the upper part of the profile is missing, saline lake sedimentary record is interrupted. It might have been explained with the continued vigorously arid incident, making the lake shrink back and causing a water level fall-down. Otherwise, by the hundred-thousand timescales, distinguished clearly that after 22.70 ka BP in Dahyab Tso, there are 8-time cold palaeoclimate events, 3-time wet palaeoclimate events, and 2-time frequently fluctuation palaeoclimate events. Depended on that, it can be divided into 19 stages during 18.2 ka in more detail. The 8-time cold palaeoclimate events are: ①circ. 22.70-21.92 ka BP, a duration of 780 a;②circ. 20.48-919.25 ka BP, a duration of 1230 a,the coldest palaroclimate event;③circ. 17.80-16.02 ka BP, a duration of 1 780a;④circ. 15.46-15.13 ka BP, a duration of 330 a,the shortest palaeoclimate event;⑤circ. 12.31 -11.76 ka BP, a duration of 550 a;⑥circ. 11.50-10.73 ka BP, a duration of 770a;⑦circ. 10.43-8.19 ka BP, a duration of 2240a,the longest palaeoclimate event;⑧circ. 7.10 -6.26 ka BP, a duration of 840a。The 3-time wet palaroclimate events are: ①circ. 16.02-14.68 ka BP, a duration of 1 340a, the wettest and the longest palaeoclimate event;②circ. 13.93-13.41 ka BP, a duration of 520a;③circ. 13.41-12.71 ka BP, a duration of 700a.The 2-time frequently fluctuating palaeoclimate events are: ①circ. 13.41-12.71 ka BP, a duration of 700a, a period of frequent fluctuation between dry and slightly humid in a mild background; ②circ. 10.43-8.19 ka BP, a duration of 2240a, a period of requent fluctuation in coldness varying degrees and accompanying with transfer from slightly humid to slightly dry in a extremely cold background.(2) Discovery of the two new fossil species of the diatom - one in Mastogloia Thwaites named Mastogloia tibetica Li et Wei, the other in Cymbella Agardh named Cymbella taicuonensis Li et Zheng - is of great significance, because it is the first time in the Tibetan area that a new specie in Mastogloia Thwaites has been found. The discovery of these two new fossil species is of important significance to both the taxonomy and the palaeoecology of the lakes sediment environment. They both can be used as effective substitute indexes for palaeoclimate and the palaeoenvironment by clarifying the water environmental habits and the salinity adaptability of the two new fossil species.(3) It is the first time to find a great amount of Cyprideis torosa and C. littoralis in Tibet, which have never been found in the sediments from Tertiary to present day in the coastal areas of South-west China, and South China, as well as the States in South-west Asia. To further find out the spatial and temporal distribution of both new species will be of important significance to understanding both the distribution of palaeo-biography and reconstruction of palaeoenvironment in Tibet.
中文关键词	盐湖 ; 硅藻 ; 孢粉 ; 介形虫 ; 古气候 ; 西藏
英文关键词	saline lake diatom palynology ostracod palaeoclimate
语种	中文
国家	中国
收录类别	CSCD
WOS类目	PALEONTOLOGY
WOS研究方向	Paleontology
CSCD记录号	CSCD:2932745
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/220815
作者单位	1.中国地质科学院, 北京 100037, 中国; 2.中国地质科学院矿产资源研究所, 北京 100037, 中国; 3.中国地质科学院地质研究所, 北京 100037, 中国; 4.石家庄经济学院资源学院, 050031; 5.中国地质科学院水文地质环境地质研究所, 石家庄, 河北 050803, 中国
推荐引用方式 GB/T 7714	魏乐军,刘建华,李家英,等. 西藏台错古生物记录的古环境事件及硅藻、介形虫化石新发现[J],2007,81(9):1169-1182.
APA	魏乐军,刘建华,李家英,庞其清,&童国榜.(2007).西藏台错古生物记录的古环境事件及硅藻、介形虫化石新发现.,81(9),1169-1182.
MLA	魏乐军,et al."西藏台错古生物记录的古环境事件及硅藻、介形虫化石新发现".81.9(2007):1169-1182.