内蒙古四子王旗呼和淖尔全新世孢粉记录的植被和气候变化

发布时间：2018-05-08 04:13

本文选题：季风边缘区 + 全新世　；参考：《内蒙古大学》2017年硕士论文

【摘要】：我国季风边缘区全新世气候时空演化规律及驱动响应机制的研究可为认识季风系统变化机制,预测未来气候变化规律及生态响应提供借鉴。本文选取内蒙古四子王旗呼和淖尔地区HH孔湖泊沉积物的岩芯为研究对象,以AMS14C年代为框架,利用湖泊沉积物孢粉和粒度等代用指标,高分辨率地重建了呼和淖尔地区全新世的古植被和古气候变化,并通过与区域内及区域外的古气候记录进行对比分析,探讨了季风边缘区全新世气候变化的时空分布规律,并对其驱动机制进行简单的讨论。初步取得的结论和认识如下:(1)利用HH孔的14个AMS14C测年结果,结合科学评估碳库效应,分段线性回归建立了 HH孔年代-深度模式,经过拟合后得到两段相关系数较高的模式,并且获得岩性的底部年龄为9820 cal.yr BP。(2)以建立的年代模型为框架,利用孢粉组合,并结合孢粉生物群区化指数、孢粉定量重建气候序列、岩性和粒度等代用指标,高分辨率重建了呼和淖尔地区9820 cal.yrBP以来的植被和气候变化:9820～9590 cal.yrBP,研究区植被为草原,气候较湿润;9590～8260 cal.yrBP,草原覆盖进一步增加,区域气候湿润;8260～7380 cal.yrBP,研究区植被依然为草原,但荒漠草原成分有所增加,气候略变干;7380～6900cal.yrBP,植被恶化为荒漠或草原化荒漠,当地植被不发育,区域气候干旱;6900～3580 cal.yrBP,植被好转为荒漠化草原,气候略变湿润;3580～2520 cal.yr BP,草原退缩,荒漠组分增加,气候变干;2520 cal.yr BP～至今,研究区植被发育为荒漠草原或草原化荒漠,气候进一步变干。(3)通过呼和淖尔与区域湖泊全新世气候的对比可知,呼和淖尔重建的气候变化与白淖尔及巴彦查干具有较高的一致性,均揭示了早全新世湿润,中全新世变干的气候特征;与区域外湖泊记录的全新世气候对比结果表明,呼和淖尔反映的气候特征与青海湖、湖光玛珥湖、星云湖、董哥洞石笋、科桑洞以及阿尔泰Hoton-Nur所重建的全新世气候较为相似,均表明早全新世降水较多,气候湿润。
[Abstract]:The study on the spatial and temporal evolution of the Holocene climate and the driving response mechanism in the marginal region of the monsoon in China can be used as a reference for understanding the mechanism of monsoon system change and predicting the future climate change law and ecological response. In this paper, the core of lake sediments in HH hole in HH hole in Siziwang Banner, Inner Mongolia, is selected as the research object. The AMS14C age is taken as the frame, and the proxy indexes such as sporopollen and granularity of lake sediments are used. The paleovegetation and paleoclimate changes of Holocene in Huhe Nur area were reconstructed in high resolution. By comparing with paleoclimate records in and out of the region, the temporal and spatial distribution of Holocene climate change in the marginal area of monsoon was discussed. The driving mechanism is briefly discussed. The preliminary conclusions and understandings are as follows: (1) by using 14 AMS14C dating results of HH hole and combining with the scientific evaluation of carbon pool effect, a piecewise linear regression model of HH hole age depth is established, and the model with higher correlation coefficient is obtained after fitting. And the bottom age of lithology is 9820 cal.yr BP.Y2) based on the established age model, using sporopollen assemblage, combining with sporopollen biota index, sporopollen quantitative reconstruction of climate sequence, lithology and granularity, etc. The vegetation and climate change since 9820 cal.yrBP in Huhe Nur area were reconstructed in high resolution. The vegetation in the study area is grassland, with a humid climate of 8260 cal.yrBP. the grassland cover is further increased, and the regional climate is humid, 7380 cal.yrBP.YrBP. the vegetation in the study area is still steppe. However, the composition of desert steppe was increased, the climate of desert steppe was slightly changed from 7380 to 6900cal.yrBP, the vegetation became desert or steppe desert, the local vegetation was not developed, the regional climate was dry and dry, the vegetation became desertified steppe, the climate changed to desertification steppe, the climate changed slightly to 3580,2520 cal.yr BP, and the steppe retreated. The vegetation in the study area developed into desert steppe or steppe desert, and the climate became drier by comparison of the Holocene climate between Huhe Nur and regional lakes. The climate change reconstructed by Huhe Nur is consistent with that of Bainur and Bayan Chagan, which reveals the climate characteristics of the early Holocene and the Middle Holocene, and the comparison with the records of the lakes outside the region shows that the climate of the early Holocene is humid, and that of the Middle Holocene is dry, and the results are compared with the records of the lakes outside the region. The climatic characteristics reflected by Huhe Nur are similar to those reconstructed from Qinghai Lake, Huguang Maer Lake, Xingyun Lake, Dong GE Dong stalagmites, Kosang Cave and Altai Hoton-Nur, all of which indicate that the early Holocene precipitation was more frequent and the climate was humid.
【学位授予单位】：内蒙古大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q914;P532

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