二龙湾玛珥湖年纹层湖泊沉积物元素的X射线荧光光谱分析  

Environment instruction significance and character of element geochemistry based on synchrotron radiation techniques from varved lake sediments of Erlongwan Maar Lake

作　　者：游海涛[1] 孙春青[2] 李全林[3] 刘嘉麒[2] 

机构地区：[1]中国科学院大学地球科学学院中国科学院计算地球动力学重点实验室,北京100049 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国科学院高能物理研究所,北京100049

出　　处：《核技术》2015年第2期1-9,共9页Nuclear Techniques

基　　金：国家自然科学基金项目(No.41472320)资助

摘　　要：运用同步辐射X射线荧光光谱分析技术对二龙湾玛珥湖0-485 mm(AD1282-AD1988)区间年纹层沉积物进行了分析,获得了Ti、Mn、Br等6种高分辨率元素含量。并对元素进行了因子分析,提取出控制沉积物化学组成的三个主要因子:早期成岩因子F1、生物成因因子F2和流域侵蚀因子F3。进一步的研究还发现,F2和F3的因子得分分别可以作为气候冷暖和干湿变化的代用指标,从而为古气候古环境重建提供了一条有效的新途径。结合高分辨率纹层年代学结果,初步评价了过去700年来该区域气候及环境演化历史。小冰期在二龙湾地区结束于AD1890年,期间波动较大,但不是表现为持续冷气候,共经历了三次冷波动集中时期。进入AD1890年以来,该区整体上呈现温暖湿润气候,但具体表现为温度逐渐降低、降水量逐渐增加的趋势,直至AD1985年降水量回落,温度转而升高。这是20世纪气候变暖在该区域的反映。Background： High-resolutionary lacustrine sediments from Maar Lakes are very important to construct and understand the mechanism of paleoclimatic changes. Purpose： To study the tendency of climatic changes and the global warming in the 20th century, proxy indexes for temperature and precipitation during the Late-Holocene （from AD1282-AD1988） were obtained by high-resolutionary geochemical analysis on the varved sediments of Erlongwan Maar Lake （Northeastern China）. Methods： Synchrotron radiation X-ray fluorescence spectroscopy （SRXRF） was performed on the lake sediments from Erlongwan Maar Lake and six elements including As, Br, K, Mn, Rb and Ti were obtained. Factor analysis on these elemental data was used to facilitate the interpretation of the results. Results： The three main factors, F1, F2 and F3, were extracted. These three factors are related to early diagenesis, biogenesis factor and basin erosion, respectively. The F2 and F3 scores may also be used as climate proxy indexes for changes in temperature and precipitation, respectively. Varve chronology over past 700 years from this core gives a precise time scale for evaluating this sediment sequence, climatic and environmental changes. Conclusion： Particularly during the Little Ice Age （LIA）, the climate was not homogenous but characterized by three cold spells. After AD1890, the region had generally a warm and humid climate and concomitant trends of rising temperature and falling precipitation could be observed as a reflection of global warming in the 20th century.

关 键 词：X射线荧光分析 湖泊沉积物 元素地球化学特征 二龙湾 环境变化记录 纹层年代学 

分 类 号：TL99[核科学技术—核技术及应用]