Knowledge Resource Center for Ecological Environment in Arid Area
| 浑善达克沙地的光释光测年研究 | |
| 韩鹏 | |
| 出版年 | 2004 |
| 学位类型 | 硕士 |
| 导师 | 孙继敏 |
| 学位授予单位 | 中国科学院地质与地球物理研究所 |
| 中文摘要 | 风成沉积物对于干旱和半干旱地区古气候和古环境的重建是至关重要的。在中国，活动沙丘主要在西北内陆盆地，而半固定的沙丘占主导的沙地主要分布在中国的东北。最近的研究表明中国东北部正面临快速沙漠化，深入研究中国东北古环境变化十分关键。以前本区域的研究多集中在大尺度的环境变化研究，全新世以来的环境变化研究较少。本文选取了浑善达克沙地为主要研究对象，发挥光释光技术的优势对浑善达克沙地的样品进行测年。为风成活动和古环境的重建提供精确的时间标尺，并将其环境演化和其他几个沙漠（地）已有的环境资料进行了对比。得出以下的一些结论：1、中国东北的活动沙丘从末次盛冰期持续到10o00aB.P.左右，全新世的温暖湿润的气候在2800～1800aB.P.被干冷的气候打断；2、全新世气候适宜期大约在10000-2800aB．P．左右；最近的暖湿阶段至少应该在1900-1500aB．P．之间3、浑善达克沙地中最年轻的古土壤大约90aB．P，其上沉积着更年轻的风成沙，呼伦贝尔沙地中最年轻的风成沙大约40aB．P．。但这些沙地都位于中纬度地区，属中温带半湿润、半干早大陆性季风气候区。大部分地区年平均降水可达450mm，这样的气候条件下在这一地区不应该形成大面积的流动沙丘。所以，现代东北地区流动沙丘的出现并非自然因素起主导作用，而是农垦及过度放牧等人类活动所导致\ |
| 英文摘要 | Eolian deposits are important for paleoclimatic and paleoenvironmental reconstructions in arid and semi-arid regions. In China active sand dunes mainly occur in the northwest inland basins ,whereas deserts dominated by semi-stabilized sand dunes are mainly distributed in the northeastern semi-arid and sub-humid regions. Recent studies indicate that prompt desertification in northeastern China has been serious.Thus northeastern China is one of the key sites on which to study the history of past environmental changes. However, previous studies focused mainly on big scale environmental changes, whereas changes in the environment during the Holocene have not been well studied. This research uses optically stimulated luminescence to date fossil sand dunes in Hunshandake desert in order to offer the accurate time scale to reconstruct the history of eolian activity in the region. Furthermore,we compare this region with other deserts in northern China.The main conclusions is following: Active dune formation in northeastern China lasted from the Last Glacial Maximum to about 10 000aB.P. It has also been shown that the warm climate of the Holocene was interrupted by a cold/dry dune-forming episode at about 2 800-1 800aB.R. The Holocene Optimum occurred between 10 000-2 800aB.R, and a later warm/humid dune stabilization phase lasted from at least 1 900-1 500aB.R. The youngest age on the uppermost soil unit in Hunshandake desert yielded an age of 90aB.P.,on which the younger sand deposits,and the youngest age on the sand in Hulun Buir desert is 40aB.R. The mean annual precipitation of these regions is up to 450 mm. But these deserts locate in middle latitudes regions, where the climate is sub-humid, semi-arid continental monsoon.Under present climatic conditions, there should be no active sand dunes in northeastern China. So the appearance of active sand in northeastern China is not due to natural factors,but to extensive land reclamation and cultivation. |
| 中文关键词 | 光释光 ; 全新世气候适宜期 ; 末次盛冰期 |
| 英文关键词 | Optical dating The Holocene Optimum Last Glacial Maximum |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源机构 | 中国科学院地质与地球物理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/286350 |
| 推荐引用方式 GB/T 7714 | 韩鹏. 浑善达克沙地的光释光测年研究[D]. 中国科学院地质与地球物理研究所,2004. |
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