【作者】 杨琰；

【导师】 袁道先；

【作者基本信息】 中国地质大学 ， 水文学及水资源， 2006， 博士

【摘要】 地球环境的日趋恶化是科学面临的严峻挑战，针对这些全球性的环境问题国内外学者提出了全球变化研究这一重大科学课题，通过预测全球变化及其对人类生存环境的影响，提出适应与减缓全球变化的对策，最终实现人与自然协调可持续发展。要提高对全球变化的预测力，必须对过去全球变化有充分的认识和了解，因而在全球变化研究中，过去全球变化是全球变化研究中的一项重要研究内容。我国在过去全球变化的研究中处于较重要的地位，一方面我国的气候受全球大气物理系统的影响而具有全球性一般特点；另一方面由于我国特殊地理位置而使其气候变化又有着自身的一些特点，如季风气候特征明显，大陆性气候强，且气候类型多样。因此，对我国古气候变化的研究无疑会对全球变化模型的建立和对我国区域气候变化的预测均具有很重要的意义。 洞穴石笋的形成过程与大气圈、水圈、生物圈、岩石圈有着密切的联系，大气降水在生物圈和岩石圈的运移过程中不断有岩溶作用发生，在岩溶作用发生过程中形成的洞穴石笋对外部环境变化反应非常敏感，可以记录几十万年以来气候、生态的变化规律以及人类活动对环境改造的信息，所以洞穴石笋是一种不可多得的陆地古环境信息源。我国南方分布着面积为5.4×10⁵km²的岩溶区，岩溶洞穴极其发育，洞穴石笋在其生长过程中可以记录季风及赤道复合带交互作用的变化特点等。通过对岩溶记录的研究无疑可以恢复或重建该地区的古气候和古环境的变化模式，为岩溶地区人与自然可持续协调发展提供科学依据。石笋记录研究的进展与测年技术的发展密不可分，测年新技术的突破不断推动石笋重建古气候研究的飞速前进，所以，在利用石笋进行古气候重建过程中，建立精确的时标是首要条件。 本文通过对洞穴石笋高精度ICP-MS铀系年代学方法的研究，并在此基础上对贵州荔波县衙门洞Y1石笋进行了古气候重建研究，综合²³⁰Th测年数据研究和Y1石笋稳定同位素的分析结果，初步认为： （1）精确时标的建立对于利用石笋进行古气候重建具有重要的实际意义，采用ICP-MS²³⁰Th测年方法进行石笋样品定年准确可靠，并且比TIMS方法具有更高的效率，所需样品更微量，使获得更高精度定年结果成为可能；本文通过石笋高精度ICP-MS铀系年代学方法的研究，对其测年核心技术问题和工作思路有一定的了解。 （2）通过对较老石笋的ICP-MS ²³⁰Th测年研究，发现贵州荔波县董歌洞D6、D7、D9石笋具有比较连续的高分辨记录，最老年龄超过40万年，通过²³⁰Th测年数据的分析为我国西南地区50万年以来标准剖面建立打下基础；从石笋²³⁴U／²³⁸U放射性比值和生长速率变化分析表明，²³⁴U／²³⁸U放射性比值可以记录过去突变冷暖事件的变化，可以作为一个有意义的环境记录替代指标来研究古降水及古气候变化，此研究也是本文的主要创新点之一。更多还原

【Abstract】 The deterioration of global environment is a big challenge to scientists, therefore global changes research as an important scientific project has been researched in the all over the world. To forecast global changes and estimate it impact on survival condition of human and bring forward some advices in decreasing those deterioration, we can keep harmony and sustainable development with nature in the end. To improve ability to forecast present, we should have good knowledge of the past global changes, which is a key point in global changes research. There are many advantages to research past global changes in China, on the one hand, which have some global general climatic characteristics induced by global atmospheric physical system; on the other hand, which have some unique climatic characteristics induced by special geographical location, such as distinct monsoon climate, strong continental climate and various climatic types. Therefore, researching past global climate changes of China have very significant advances on establishing global climate changes model and forecasting local climate changes in China.Forming of cave stalagmites has close relation to atmosphere, hydrosphere, biosphere and lithosphere. There are continuous karstification occur, when atmospheric precipitation move in biosphere and lithosphere. Stalagmites very well respond to the external environmental changes during forming with karstification, as good preservation of environmental signals which can record information of reconstructive nature by human and climatic and ecological changes from hundred thousand years ago. Therefore, stalagmites are good archives of past climatic changes in continent. There is 5.4×10⁵km² karst region in the South of China, and caves well develop. As a good geological archive, stalagmite can record interaction changes of the monsoon and the intertropical convergence zone （ITCZ）, which connected to the past climate changes in the South of China. We can reconstruct paleo-climatic and paleo-environmental change mode via researching stalagmites records, which can provide the scientific foundation for sustainable development between human and nature in the Karst region. Advance of researching in stalagmites keep pace with the development dating technique, and new dating technique administer to develop rapidly in reconstruction paleoclimate by stalagmites. Therefore, the precise chronology established is the first factor for reconstructing paleo-climate by stalagmites. This dissertation firstly research on high precision ICP-MS uranium series chronology methods, base on the chronology research we reconstruct paleo-climate by stalagmite Y1 records from Yamen Cave, Libo County, Guizhou Province, China. From researching of ²³⁰Th data and stable isotopes data of stalagmite Y1, the following conclusions can be made.（1） The precise chronology established has the practical significance to reconstruct paleo-climate by stalagmite; ICP-MS ²³⁰Th dating method is accurate and credible, which has更多还原