中国近海泥质沉积物粒度特征的指示意义研究

发布时间：2018-01-07 23:17

本文关键词：中国近海泥质沉积物粒度特征的指示意义研究　出处：《中国科学技术大学》2017年硕士论文　论文类型：学位论文

【摘要】：中国近海泥质沉积物敏感粒级的平均粒径已被广泛用于重建东亚冬季风强度,但不同研究重建的结果之间存在一定差异,且近年来不断有学者对一些区域泥质沉积物敏感粒径的指示意义提出不同观点。此外,之前在黄、东海泥质区的研究集中于整个全新世特别是中晚全新世以来较长时间尺度冬季风记录的重建,对不同泥质区高分辨率的沉积记录与器测数据的对比较为缺乏,使得利用泥质沉积物重建古气候记录的研究基础仍较为薄弱。为探讨不同时间尺度上,黄、东海不同泥质区沉积物敏感粒度影响因素的复杂性及其能否用于重建东亚冬季风强度,本文首先搜集了前人利用泥质区沉积物敏感粒度重建冬季风的数据资料并进行了对比分析;进而利用敏感粒级提取和地球化学元素分析等方法,对北黄海西部泥质区38002孔、南黄海中部泥质区35009孔、长江口泥质区T02孔三根插管柱样以及北黄海西部泥质区38002-A重力柱样进行了研究,以探讨不同区域敏感序列之间的关系以及影响粒度变化的可能机制。主要研究内容和结论如下:(1)分别对比了不同研究利用泥质区敏感粒度重建的近8000年和3000年来的冬季风强度序列,发现不同冬季风记录的变化趋势之间存在显著差别,分析认为产生这些差异的可能原因包括年代误差、敏感粒度组分(Sensitive Grain Size,SGS)的选取不同以及不同研究区域的沉积环境差异等。(2)在年代相对较为精确以及敏感粒度组分的选取较为一致的前提下,发现近百年来,三个不同泥质沉积区的敏感粒度序列之间的变化趋势并不完全一致,且均与西伯利亚高压变化趋势不同。在年代际时间尺度上,北黄海西部泥质区和南黄海中部泥质区由于特殊的成因机制,可能受冬季风驱动的沿岸流影响较小,长江口泥质区则受长江输沙等因素的影响较大,导致这些区域沉积物的敏感粒径变化均与反映冬季风强度的西伯利亚高压指数序列无显著相关,证实了泥质区形成机制和沉积环境的差异会对敏感粒度特征产生较大影响。(3)进一步,本研究选择北黄海西部泥质区沉积物进行更长时间尺度上的研究。结果显示,晚全新世以来,该泥质区38002-A孔沉积物的敏感粒度组分及相关的元素比值等更多受到夏季风控制的黄河流域降水的影响,受东亚冬季风的影响较小。综上所述,我国近海泥质区沉积物的粒度特征受多种因素的影响,在利用泥质沉积物敏感粒级的平均粒径作为东亚冬季风强度的替代指标时需谨慎,应考虑沉积物所在区域的沉积机制,尤其是环流体系及河流输沙等因素的影响。尽管目前对于我国黄、东海陆架泥质区的研究有了一定的认识,以后仍应加强对泥质区沉积动力机制和过程的研究,尤其是敏感粒度变化对气候变化的响应机制等方面的研究,进一步探讨不同时间尺度上不同泥质区沉积物敏感粒度作为东亚冬季风指标的可靠性。
[Abstract]:The average particle size of sensitive grains in China offshore mud sediments has been widely used to reconstruct East Asian winter monsoon intensity, but there are some differences between the results of different studies. In recent years, some scholars have put forward different views on the indication of sensitive particle size of mud sediments in some regions. The study of the muddy area in the East China Sea focuses on the reconstruction of winter monsoon records in the whole Holocene, especially since the middle and late Holocene. Therefore, the study of paleoclimate record reconstruction using muddy sediments is still weak. In order to discuss the different time scales, yellow. The complexity of the factors affecting the sensitive granularity of sediments in different muddy areas of the East China Sea and whether they can be used to reconstruct the East Asian winter monsoon intensity. In this paper, the data of winter monsoon reconstruction using sediment sensitive granularity in muddy area were collected and compared. Then, by means of sensitive grain-level extraction and geochemical element analysis, 38002 holes in the muddy area in the west of Huang Hai in the north and 35009 holes in the middle of the South Huang Hai were selected. The three tube column samples of T02 hole and the 38002-A gravity column of northern Huang Hai were studied in the muddy area of the Yangtze River Estuary. In order to explore the relationship between sensitive sequences of different regions and the possible mechanism of influencing grain size change, the main contents and conclusions of the study are as follows: 1). The winter monsoon intensity series of recent 8000 and 3000 were compared by using sensitive granularity reconstruction of muddy area. It is found that there are significant differences between the trends of different winter monsoon records, and the possible causes of these differences include year errors. Sensitive Grain Size. The selection of different SGSs and the difference of sedimentary environment in different research areas, etc.) in the premise of relatively accurate age and relatively consistent selection of sensitive granularity components, it was found that in the last hundred years. The change trend of sensitive granularity sequences in three different muddy sedimentary regions is not completely consistent, and is different from that of Siberian high pressure, and is different from that of Siberian high pressure in Interdecadal time scale. Due to the special genetic mechanism, the muddy areas in the western part of Huang Hai in the north and in the middle part of the South Huang Hai may be affected less by the coastal currents driven by the winter monsoon, while the muddy areas in the Yangtze River Estuary are more affected by the sediment transport along the Yangtze River. There was no significant correlation between the change of sensitive grain size and the Siberian high index series which reflected the intensity of winter monsoon. It is proved that the difference of the formation mechanism and sedimentary environment of the muddy area will have a great influence on the sensitive granularity characteristics. In this study, the sediments in the mud area of the western part of Huang Hai were studied on a longer time scale. The results showed that since the late Holocene. The sensitive granularity components and the relative element ratios of the sediment in the muddy area are more affected by the precipitation in the Yellow River basin controlled by the summer monsoon than by the East Asian winter monsoon. The grain size characteristics of sediments in China's offshore muddy areas are affected by many factors. It is necessary to be cautious in using the average particle size of sensitive grains of muddy sediments as an alternative indicator of East Asian winter monsoon intensity. The sedimentary mechanism of the area where the sediment is located should be considered, especially the influence of the circulation system and the river sediment transport, etc. Although there is a certain understanding of the study on the muddy areas of the Yellow and East China Sea shelf in China. In the future, the study on the dynamic mechanism and process of sediment in muddy area, especially the response mechanism of sensitive granularity change to climate change, should be strengthened. The reliability of the sensitive granularity of sediment in different muddy areas as an index of East Asian winter monsoon is further discussed in different time scales.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P736.21

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