Knowledge Resource Center for Ecological Environment in Arid Area
| 末次冰盛期以来中国东部沙地空间分布特征及环境记录 | |
| 其他题名 | Distribution and Environment of Deserts of Eastern China since LGM |
| 杨利荣 | |
| 出版年 | 2007 |
| 学位类型 | 博士 |
| 导师 | 丁仲礼 |
| 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 | 末次冰盛期－全新世是第四纪以来距今最近的、变化幅度很大的气候转型期，本论文旨在恢复这一特征时段我国东部沙地空间格局的变化，重建这两个时期沙漠古范围和古环境。沙漠风积物地层以风成砂单元和砂质土壤单元的交替出现响应气候的变化，前者反映干旱期，后者反映湿润期。我国东部沙地近地表以下发育一套对比强烈的地层单元－松散风成砂和上覆黑色砂质土壤，发育程度较高的砂质土壤是全新世适宜期的产物，因此下伏的厚层风成砂层为末次冰期晚期的产物。对三个沙地近50个风积剖面底层风砂进行了光释光年代的确认，通过剖面位置、戈壁－沙漠－黄土空间分异的规律以及地形控制综合分析恢复了末次冰盛期这些沙地的空间范围。呼伦贝尔沙地、浑善达克沙地由于其东部大兴安岭山脉的阻挡，在山前结束的末次冰盛期古沙漠位置不完全受气候背景的控制。科尔沁沙地东部边界地势平坦，末次冰盛期古沙漠边界主要受气候带迁移的控制。根据区域水系发育的特点和颗粒形态特征，认为末次冰期呼伦贝尔沙地的风砂有相当一部份来源于本地河流沉积物。全新世适宜期广泛发育的土壤层表明三个沙地基本固定，总体呈荒漠草原景观。末次冰盛期－全新世适宜期东部三个沙地的空间格局变化是LGM强烈扩张的流沙在进入全新世后逐渐固定收缩，至全新世适宜期已完全固定并呈现荒漠稀树草原景观。\n 通过对末次冰盛期以来发育较为完整风积剖面光释光年代学研究，结合粒度、磁化率、TOC、色度以及扫描电镜测试，初步认为三个沙地经历了四个阶段的演化：末次冰消期风成砂发育(15-10ka)—全新世早期黑色砂质土壤发育（10-5ka）—全新世中后期砂质土壤与流沙（风河）交互发育—近千年来土壤受破坏。 |
| 英文摘要 | The latest two extreme scenarios of last glacial maximum and Holocene climatic optimum marked extreme situations in China. This paper aims to reconstruct the fossil extensions and paleoclimate of deserts in eastern China during this typical period. Aeolian sequence responds the climate change by virtue of alternation of aeolian sand layer and sandy soil layer, which correspond aridity and humidity, respectively. There is a set of contrastive deposits made up of loose sand layer and overlying dark sandy soil below land surface. This developed soil and underlying deep aeolian sand respond to H.O. and late last glacial, i.e. LGM. The typical bottom sand layers of about 50 profiles of Hulun Buir Desert, Horqin Desert and Otindag Desert were dated using OSL to confirm that they did deposid in LGM. Based on the locations of these LGM sand, distrution of gobi-desert-loess and landform control, the distribution in LGM of the three deserts were reconstructed. For the block of eastern mountain, the extreme eastern boundary of Hulun Buir Desert and Otindag Desert are not just functioned by climate background. The east of Horqin Desert is plain, hence eastern boundary of this desert is maily controlled by climate. It is considered that quite a lot of aeolian sand of LGM origined from fluvial deposit by observing regional distribution of river and SEM of sand grains. The environment alternation of of LGM-H.O. is featured by extensive expanse of active dune in LGM and grassland in H.O.\n Combined grain-size, susceptibility, TOC, colour and SEM measurement, the OSL chronology of relatively continued profiles since LGM of the three deserts are divided into four periods: eolian sand (15-10ka)- sandy soil (10-5ka)- alternation of black sand and yellow sand- reworking of LGM sand as destroy of soil. |
| 中文关键词 | 呼伦贝尔 ; 科尔沁 ; 混善达克 ; 中国东部沙地 ; 末次冰盛期-全新世适宜期 ; 空间格局变化 ; 光释光测年（OSL） |
| 英文关键词 | Hulun Buir Desert Otindag Desert Deserts in eastern China LGM-H.O. Expansion and contraction OSL dating |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 第四纪地质学 |
| 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/2XILL650/286546 |
| 推荐引用方式 GB/T 7714 | 杨利荣. 末次冰盛期以来中国东部沙地空间分布特征及环境记录[D]. 中国科学院地质与地球物理研究所,2007. |
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