【作者】 王谋；

【导师】 李勇； 李亚林；

【作者基本信息】 成都理工大学 ， 第四纪地质学， 2005， 博士

【摘要】 青藏高原以其独特的地形地貌,深深地影响了亚洲乃至北半球的气候与环境,从而造成影响区域内生态环境类型的分异。同时,青藏高原作为良好的地质环境演化过程的记录体,作为公认的气候变化的启动区、全球变化的敏感区域,越来越多地吸引了各学科领域对研究青藏高原的关注,在地质学、地理学、生态学、环境学、气候学等科研领域,青藏高原已经成为国际研究热点。青藏高原腹地,作为长江源区,其生态环境演化过程及未来演化趋势的分析尤具科学与国民经济可持续发展的重要性,而受到科学前沿和政府的重点关注。 然而,多种原因导致高原腹地研究程度较低海拔地区相对不足,并由此而产生了一些研究盲点和科学争论。本文正是选取了与高原腹地生态环境演化过程及现代生态环境演化趋势相关的空白研究领域及基础研究比较薄弱的领域,开展针对性的研究工作。并综合运用孢粉学、植被生态学、同位素地球化学、环境地球化学、环境磁学、沉积学等研究方法,获取了大量具有创新意义的研究资料,对高原气候变化历史及青藏高原表面隆升过程进行了讨论,尤其是对现代生态环境及生态环境演化趋势分析极为相关的中全新世以来高原腹地气候变化规律进行了典型剖面的重点研究,并建立在高原腹地生态环境历史演化分析的基础上,进一步对现代高原腹地生态环境状况及演化趋势进行了探讨。得出如下结论: （1） 采自高原腹地新生代地层中最新的孢粉分析资料并部分结合前人研究资料显示青藏高原自始新世以来共发生了5次具有生态环境改造意义的表面隆升事件,而导致高原面阶段性的抬升至现今的高度。孢粉组合反映,高原腹地植被演化经历了温带阔叶林—山地针叶林—稀树草原—高寒草原、高寒草甸的逆行演替过程。最新孢粉分析资料显示,始新世—渐新世雅西措组地层以山地针叶林植被较发育,推测高原表面隆升高度在1000～15000m;新近系五道梁组植被组成较渐新世中亚热带成分大幅上升,可能与中新世高原表面隆升引发原始高原季风而导致气候温湿有关,并据此推测高原面高度在2000m左右:中更新世孢粉组合以草本植物为主,反映出当时生态环境已不具备大规模发育木本植被水热条件,高原表面隆升高度应在4000米以上:全新世孢粉组合则显示了自中全新世以来稀树草原-荒漠草原-高寒草原的植被演化特征,反映了高原表面隆升导致生态环境变化原因之外的全球气候变化对高原生态环境的控制意义,并表现出两千年周期的气候波动规律。 （2） 为了更好地认识现代气候过程和预测未来的气候演化趋势,在讨论了高原新生代以来表面隆升导致的气候演化一级旋回后,论文对中晚全新世以来气候演化的次级旋回进行了重点研究。刻莫土壤剖面位于研究区东北部,是一套风成沉积的砂土剖面。其底部¹⁴C年龄为6380aBP。因风成堆积体在时间记录的连续性方面尚存争议,高原腹地几乎没有关于风成土壤与气候演化的相关性讨论。但风成砂土粒度特征、有机质碳同位素组成及磁化率特征等指标都能非常直接的与现代进行对比,而避免了经验换算或量度转换过程中的信息失真。更多还原

【Abstract】 The Qinghai-Tibetan Plateau is a unique tectonic unit whose uplift not only resulted in its own evolvement of environment and ecology, but also influenced and changed the climate and environment of neighboring area and the globe at the same time by giving an impact on the atmospheric circumfluence. The plateau uplift is a staged historic process that is recorded by the sediments through which we can clearly understand the information of plateau development and environmental transition. Because huge high mountains have magnifying action on climate changes, the Qinghai-Tibetan Plateau has also become the main study area of the Quaternary climate, environment and geology. As the background of regionally ecological evolvement, the uplift event of Qinghai-Tibetan Plateau and evolution of environment and ecology caused by uplift are analyzed in this paper, the time of plateau uplift and magnitude are concisely discussed. By using the flora ecological method, isotopic geochemistry, environmental geochemistry, environmental magnetics and sedimentology et al., the process of plateau climatic changes and ecological evolvement are discussed as emphases in the paper; aiming at the global warming and vegetation adapting of the way, extent and evolution-trend in modern times, the accordingly changed environment and ecology are detailed studied and the main conclusions are as follows:(1) Based on the information of sporopollen in Tongtianhe basin stratum profile and contrast study of to neighboring area, there have been 5 times of tectonic uplift in the Qinghai-Tibetan Plateau since the Eocene, which brought about the staged raising of plateau to elevation of present. The analysis of spore and pollen assemblage reflected that vegetation of studied area had undergone a converse process of succession from variable zone-broadleaves t o upland conifers to Savannaand to Alpine Steppe, the Yaxicuo formation stratum of E-Oligocene mainly had upland conifers grown, and presumedly had plateau elevation of 1000— 15000m. Because the primitive plateau monsoon possibly caused by the Miocene tectonic movement had brought about warm and humid climate, the vegetation components of Wudaoliang Formation of Neogene had large rise of semitropical component and presumedly had plateau elevation about 2000m. In the late Pliocene, Tibetan plateau had a herbage blooms such as Chrysanthemun Chenopodium, species were mainly spruce and fir, representing the vegetation characteristics of Savanna, and presumedly had elevation above 3000m. In studied area, spore and pollen assemblage of middle-Pleistocene are mainly composed of herbages, reflecting the plateau elevation should be above 4000m with the approximately similar environment and ecology to that of the present.更多还原