- 责任者：Yang Lirong (State Key Laboratory of Continental Dynamics ; Department of Geology ; Northwest University ; Xi’an 710069 ; China) ; Yue Leping
- 刊名：Quaternary Sciences
- 出版年：2013
- 卷期：33(2)
- 关键词：沙漠 ; deserts ; 光释光测年 ; optical stimulated luminescence dating ; 内蒙古 ; Inner Mongolia
- 页码：p.260-268
- 图表：illus., 1 table, 53 refs.
- 分类号：1400
- issnNo：ISSN1001-7410
- isbnNo：CN11-2708/P
The Horqin dunefield is situated in the southeast of Inner Mongolia Autonomous Region which is the transition zone of Inner Mongolia Plateau and North East China Plain. The geographic coordinates is about 42°15＇ - 45 °45＇N, 118 ~15＇ -123 ~30＇E which extend to Shuangliao County and Qian＇an County to the east, Lindong County and Linxi County to the west,the east of Daxing＇anling Mountain to the north and loess hill of northern Yanshan Mountain to the south. Sixteen profiles, which are located at three north-south routes, were taken at critical points. Thirteen of them are aeolian sequences, and three of them are loess deposits. The study of grain-size, magnetic susceptibility and sediment color were applied to sequence of dark sandy soil and the underlying sand at 5 - 10cm intervals. 24 samples just below the boundary between dark sandy soils and sand were collected and dated by OSL methods. The age span of 13 - 10ka of the aeolian sand is part of the last late glacial. The c01d and dry climate leaded to continuous reworking of aeolian sand of last glacial maximum （26.5- 19.0ka）. The dune field was not totally stabilized by vegetation cover until Holocene Optimum （ 10 - 5kaB. P. ）. The results of environmental proxies such as grain size and magnetic susceptibility for the two featured profiles are presented as follows. Median grain size decreased from 150 - 200μm in last late glacial to 100 -150μm in Holocene, and the silty sand （〈631xm） increased from 10% to 40% ,which indicated that mobile dunes developed under the control of strengthened wind in last late glacial. The increase of magnetic susceptibility from 15 SI to 20 -25 SI also indicated that cold and dry last late glacial turn to warm and humid in Holocene. The area of present Horqin dunefield is 42, 000km2 , 10% of which is mobile dune. Comparatively, the mobile sand area amounted to 85,000km= during LGM including the current stable dunes,sandy plain and nearby marshland. So the sand expansion in the last late glacial was 20 times bigger than that of today. The sand supply for the dune expansion in LGM resulted from two factors： 1 ） Cold and dry climate in glacial resulted in poor vegetation cover. Loose surface deposits were eroded by wind and turned into mobile sand; 2）river system inside the Horqin dunefield is abundant. Exposed river bed during glacial period supplied sand source for dune extension.