干旱区生态环境知识资源中心(Arid): 柴达木盆地中的砂楔及其意义

Arid

	柴达木盆地中的砂楔及其意义
其他题名	CHARACTERISTICS AND IMPLICATION OF SAND-WEDGES IN QAIDAM BASIN, NORTHEAST QINGHAI-TIBETAN PLATEAU
	吴吉春 1; 盛煜 1; 赵林 2; 王生廷 1
来源期刊	第四纪研究
ISSN	1001-7410
出版年	2018
卷号	38 期号:1 页码:86-96
中文摘要	冰楔假形和原生砂楔是指示古冻土发育的重要证据。两者虽然具有相似的外观形态,但形成过程不同,在反映古气候、古环境和古冻土演化等方面具有不同的指示意义。在利用地层中的楔形构造推测古环境时,确定其类型是正确解读其环境意义的前提。本文讨论了柴达木盆地发现的楔形构造,通过楔形围岩和充填物中的一些微结构判断其属于原生砂楔,进而探讨了这些砂楔代表的环境意义和多年冻土发育状况。柴达木盆地中的砂楔主要形成在末次冰消期的Heinrich 1(H1)和Younger Drays两次降温事件期间。这表明,末次冰消期,柴达木盆地地表几乎全部被风沙覆盖,处于极端干旱的沙漠环境,年平均气温较现在降低6 ℃左右,多年冻土下界较现在下降了约1000 m。然而,多年冻土并没有占据整个盆地,在盆地中部和南部保留着大片融区,据此推测,即使末次冰期时期,柴达木盆地仍然保留一定面积的融区。末次冰期以来,青藏高原主体和祁连山两大现代多年冻土区并没有通过柴达木盆地连成一片。
英文摘要	Ice-wedges pseudomorph and relict sand wedges are important evidence for the former existence of permafrost. Similar appearance is shown in these two type periglacial features, but difference is present in their forming process. Accordingly, it is revealed that discrepant implication of palaeo-climate, palaeo-environment, and permafrost evolution. It must be validly classified of wedges when we reconstruct palaeo-environment based on periglacial wedges. In this article, we distinguished wedges as relict sand wedges based on micro-structure of filling material and host strata on the profile,and discussed palaeo-climate and permafrost occurrence during the Last Deglacial in the Qaidam Basin. Relict sand wedges were observed on profile which had been cut by building highway in Lenghu (38°51.23’N, 93°25.08’E; 2782 m a.s.l.)and Huaitou Tala(37°26.02’N, 96°14.02’E; 3760 m a.s.l.)regions, in northwestern and eastern margins of the Qaidam Basin respectively. Huaitou Tala wedges locate in a valley at 45 km west of Huaitou Tala town, and 100 km west of Delingha City. These wedges covered by loess depth of 50~ 70 cm, shaped by V,top width range 30~120 cm, depth range 1.7~3.1 m. The wedges characterized by red-brown coarse sand infilling in green silt. The fissures can be found in the fillings from top to bottom of some wedges. The OSL dating of filling sand manifested these wedges have been cracked during 11.650.99~12.661.06 ka B.P. Lenghu wedges top width range 20~50 cm and depth less than 100 cm, and they characterized by lamination in fillings and up bend of the host strata. The fillings in Lenghu wedge are 14.951.5 ka B.P. in age. Sand wedges in Qaidam Basin are identified that cracked by thermal contraction and filled by aeolian sand during Heinrich 1 and Younger Drays stadials. The Qaidam Basin had been paved by aeolian sand and very arid desert environment prevailed, and the mean annual air temperature had dropped by 6 ℃ during the Last Deglacial. Accordingly, permafrost low limit had descended about 1000 m. Nevertheless, permafrost had never occupied the whole basin floor, and it occurred in the periphery of the basin above 2800 m a.s.l. A patch of permafrost-free area persisted in the central and southern Qaidam Basin since the Last Glacial Maximum.
中文关键词	柴达木盆地 ; 砂楔 ; 末次冰期 ; 古环境 ; 古多年冻土
英文关键词	Qaidam Basin relict sand wedge Last Glacial Maximum palaeo-environment palaeopermafrost
语种	中文
国家	中国
收录类别	CSCD
WOS类目	GEOLOGY
WOS研究方向	Geology
CSCD记录号	CSCD:6157269
来源机构	中国科学院西北生态环境资源研究院
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/237484
作者单位	1.中国科学院寒区旱区环境与工程研究所, 冻土工程国家重点实验室, 兰州, 甘肃 730000, 中国; 2.中国科学院寒区旱区环境与工程研究所, 中国科学院青藏高原冰冻圈观测研究站, 兰州, 甘肃 730000, 中国
推荐引用方式 GB/T 7714	吴吉春,盛煜,赵林,等. 柴达木盆地中的砂楔及其意义[J]. 中国科学院西北生态环境资源研究院,2018,38(1):86-96.
APA	吴吉春,盛煜,赵林,&王生廷.(2018).柴达木盆地中的砂楔及其意义.第四纪研究,38(1),86-96.
MLA	吴吉春,et al."柴达木盆地中的砂楔及其意义".第四纪研究 38.1(2018):86-96.