甘肃民乐地区晚更新世以来的气候变迁

发布时间：2017-12-27 23:31

本文关键词：甘肃民乐地区晚更新世以来的气候变迁　出处：《中国地质大学(北京)》2016年硕士论文　论文类型：学位论文

【摘要】：民乐地区,居祁连山北麓,位于河西走廊的中段,属于气候变化的敏感区,而黄土又是记录第四纪时期气候变化的一大载体,因此对该地区典型的黄土剖面进行取样,分析,对于揭示该区第四纪时期气候特征的变化和预测未来环境变迁有一定的借鉴意义。论文是在榆木山活动断裂1:5万活动断层填图项目基础上完成的,本研究对甘肃民乐地区的冰沟台和董家庄剖面进行了实测,取样,并对磁化率和粒度的特征进行了分析,恢复了研究区晚更新世以来的气候环境变化特征及演化历程,并和古里雅冰芯氧同位素曲线进行了对比。得到以下结论:1,冰沟台剖面和董家庄剖面所取的粒度和磁化率数据基本合理,均表现出干冷的气候条件下,冬季风强盛,沉积物粒度普遍较大,分选较差,对应的磁化率较低。而暖湿气候背景下,冬季风较弱,沉积物的粒度较小,对应的磁化率显示也较高。并且两剖面沉积物都属于风成沉积。2,研究区晚更新世以来的气候经历了大概五个阶段的变迁,从古至今依次为:温暖湿润的晚更新世末次间冰期(122.10kaB.P.-91.36kaB.P.);(晚更新世末次间冰期晚期至末次冰期早期即91.36kaB.P.至70.23kaB.P.部分的地层及其沉积环境特点因为客观原因未能获得。);较冷的晚更新世末次冰期早期(约70.23kaB.P.-55.99kaB.P.);较温暖的晚更新世末次冰期中期(约55.99kaB.P.-23.60kaB.P.);最为干冷的晚更新世末次冰期晚期的盛冰期(约23.60kaB.P.-13.78kaB.P.);最为温暖湿润的全新世(13.78kaB.P.至今)。3,将冰沟台剖面和董家庄剖面与古里雅冰芯所记录的氧同位素曲线进行对比,发现其中存在很好的对应关系,从古至今依次对应于古里雅冰芯氧同位素的第5(e,d,c,b),4,3,2,1阶段。并且各个阶段内的一些峰值谷值也对应良好,与古里雅冰芯氧同位素曲线上反映出来的冷暖事件有着很好的响应,其中10.22kaB.P.附近出现的冷事件对应于新仙女木事件。发生在12kaB.P.附近的暖事件是对Bolling事件的响应,进一步论证了民乐地区气候的敏感性。
[Abstract]:Minle area, in the north of Qilian Mountains, located in the middle of the Hexi Corridor belongs to sensitive area of climate change, and loess is a big carrier to record the changes of Quaternary climate, so the typical loess profile in the area of sampling, analysis, to reveal the characteristics of Quaternary period climate change and forecast area has certain reference significance the future environmental changes. This paper is in the Yumushan fault 1:5 million active fault mapping project on the basis of this research on ice furrow Gansu folk area and Dong Village section were measured, sampling, and characteristics of magnetic susceptibility and grain size analyses, recovery in the study area and the evolution characteristics of late Pleistocene to climate change come, and Guliya Ice core oxygen isotope curve comparison. Get the following conclusions: 1, particle size and magnetization ice furrow profile and the profile of the Dong Village rate data is basically reasonable, showed dry climates, winter monsoon, sediment grain size is generally big, bad sorting, corresponding to the low magnetic susceptibility. In the warm and wet climate background, the winter wind is weak, the grain size of the sediment is smaller, and the corresponding magnetic susceptibility is also higher. And the sediments of the two section are all aeolian. 2, the study area since late Pleistocene climate has experienced about five stages of change, since ancient times as follows: warm and humid in the late Pleistocene and the last interglacial (122.10kaB.P.-91.36kaB.P.); Late Pleistocene (the last interglacial period to the last glacial period in early stage of 91.36kaB.P. to 70.23kaB.P. part of the stratigraphy and sedimentary environment characteristics because of objective reasons failed to get. ); cold during the last glacial period of late Pleistocene early (about 70.23kaB.P.-55.99kaB.P.); the middle warmer during the last glacial period of late Pleistocene (about 55.99kaB.P.-23.60kaB.P.); the late Pleistocene and late glacial ice cold period (about 23.60kaB.P.-13.78kaB.P.); the Holocene warm humid (13.78kaB.P. now). 3, compare the oxygen isotope curve of ice furrow profile and Dong Village section and the Guliya ice core records, found that there is a good correspondence between them, which corresponds to the Guliya ice core oxygen isotope fifth times (E, D, C, B, 4,3,2,1). And some of the values in each stage of peak valley also corresponds well with good response and reflected the Guliya ice core oxygen isotope curve and events, which appear near the cold event 10.22kaB.P. corresponds to the Younger Dryas event. The warm event near 12kaB.P. is a response to the Bolling event and further demonstrates the sensitivity of the climate in the Minle area.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P532

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