江西九江红土堆积的地球化学特征及其指示意义

发布时间：2018-05-15 15:13

本文选题：红土堆积 + 地球化学　；参考：《中国地质大学(北京)》2015年硕士论文

【摘要】：中国南方的红土堆积蕴含了大量的亚热带-热带地区第四纪古气候变迁和古环境演化信息,在恢复环境演化过程方面具有十分重要的意义。但是在利用红土堆积物反应古气候变化的指标选取尤其困难。近几年地球化学方法在风尘堆积反应古气候研究以及物质起源判断上发挥了重要作用。本文对九江地区的红土堆积物进行常量元素测试分析,对红土堆积的成因进行判断,以揭示长江中下游古气候演化的过程。得出以下结论：通过红土与洛川黄土的常量元素平均值和UCC的对比,表明九江红土与北方黄土常量元素的分布模式相似,同时与UCC分布模式也相似,指示了九江红土起源于上地壳,是典型的风成堆积物。将九江剖面的网纹红土、下蜀土和北方洛川地区的黄土、古土壤之间抗风化能力比较强的Si、Al、Ti元素的比值进行投影分析,显示了九江红土具有较高的TiO2/Al2O3值、SiO2/Al2O3值和较低的SiO2/TiO2值。同时九江地区的红土和洛川地区的黄土-古土壤的投影区域具有明显的差异性,表明了九江红土的物质来源不是来自北方荒漠。同时网纹红土和下蜀土的投影区域近乎相同,略有差异,经过对整个剖面的难迁移元素的分析,推断网纹红土和下蜀土的物质来源相同,两者之间的略微差异是由于后期风化不同造成的。运用九江剖面的网纹红土、下蜀土和北方洛川地区的黄土、古土壤之间的A-CN-K图和化学风化系数CIA变化趋势显示,九江红土达到了强烈的风化阶段,北方黄土处于中等风化阶段,显示了九江地区的成壤环境更为温暖湿润。在九江地区的红土中,网纹红土的风化强度明显强于下蜀土,通过化学风化参数系统分析,指示了九江剖面的的红土沉积过程中由暖湿的气候环境向干冷的气候发展的长期变化趋势。
[Abstract]:The accumulation of red soil in southern China contains a large amount of information on the Quaternary paleoclimate change and paleoenvironmental evolution in the subtropical and tropical regions, which is of great significance in restoring the process of environmental evolution. However, it is particularly difficult to select indicators to reflect paleoclimate change by using laterite deposits. In recent years, geochemical methods have played an important role in the study of paleoclimate and the judgement of material origin. In order to reveal the process of paleoclimate evolution in the middle and lower reaches of the Yangtze River, the elements of the laterite deposits in Jiujiang area are tested and analyzed in this paper. The following conclusions are drawn: through the comparison of the average value of constant elements and UCC of laterite and Luochuan loess, it is shown that the distribution pattern of constant elements in Jiujiang red soil is similar to that of northern loess, and the distribution pattern is similar to that of UCC. This indicates that Jiujiang laterite originated from the upper crust and is a typical aeolian deposit. Based on projection analysis of the ratios of Si-Al-Ti elements, which have strong weathering resistance between Xiashu soil and Loess in Luochuan area, Jiujiang section, it is shown that Jiujiang laterite has higher TiO2/Al2O3 value and lower SiO2/TiO2 value than Sio _ 2 / Al _ 2O _ 3 value. At the same time, the red soil in Jiujiang area and the loess paleosol projection region in Luochuan area have obvious differences, which indicates that the material source of red soil in Jiujiang area is not from the northern desert. At the same time, the projection area of reticulated red soil and Xiashu soil was almost the same, which was slightly different. Through the analysis of the hard to migrate elements in the whole section, it was inferred that the material sources of reticulated red soil and Xiashu soil were the same. The slight difference between the two is due to the later weathering difference. Using the A-CN-K diagram and chemical weathering coefficient CIA variation trend between the net red soil of Jiujiang section, Xiashu soil and Loess in Luochuan area of northern China, it is shown that the red soil of Jiujiang has reached a strong weathering stage, and the loess in the north is in the middle weathering stage. It shows that the earthen environment in Jiujiang area is warmer and wetter. In the red soil of Jiujiang area, the weathering intensity of reticulated red soil is obviously stronger than that of Xiashu soil, and the chemical weathering parameters are systematically analyzed. It indicates the long-term change trend from warm and wet climate environment to dry and cold climate in the process of laterite deposition in Jiujiang section.
【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】：2015
【分类号】：P532;P59

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