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如何有效去除海洋沉积物中的非陆源物质,同时又能完好保存陆源碎屑,是获得陆源碎屑粒度变化信息的先决条件。利用南海MD190航次的深海岩芯沉积物样品,进行了不同预处理条件下的生源物质去除效果和陆源碎屑粒度分析结果的对比研究。结合显微镜和扫描电镜观察,获得了海洋沉积物陆源碎屑粒度分析预处理方法的新认识。结果显示,对于海洋沉积物中的有机质、碳酸盐和生物硅3种生源组分,依次使用浓度为30%的H_2O_2水浴60℃震荡3 h,0.5%的HCl充分反应1 h,2 mol/L的Na_2CO_3水浴85℃震荡5 h,可以有效去除,并能兼顾去除效率以及相对完好地保存陆源碎屑。研究认为,针对不同类型的沉积物样品进行陆源碎屑粒度分析时,应考虑生源碎屑对粒度结果的实际影响,从而选择合适的预处理方案。即在确保陆源碎屑的粒度分析结果更接近真实分布的情况下,沉积物样品的预处理步骤越少越好,并非一定要去除所有的生源成分。如当生物硅含量低于2%时,其对陆源碎屑粒度分析结果的影响很小,可不用去除。另外,超声可导致部分陆源碎屑的破碎,在粒度分析预处理过程中全程不宜使用。
How to effectively remove non-terrestrial materials from marine sediments while preserving terrigenous debris is a prerequisite for obtaining information on the granularity changes of terrestrial clasts. The deep sea core sediment samples of South China Sea MD190 were used to study the removal of biogenic materials and the comparison of landfill particle size analysis under different pretreatment conditions. Combined with microscopy and scanning electron microscopy, a new understanding of pretreatment methods for particle size analysis of terrigenous debris in marine sediments was obtained. The results showed that for 3 kinds of biogenic components of marine sediments, such as organic matter, carbonate and biogenic silica, H 2 O 2 aqueous solution with a concentration of 30% was shaken for 3 h at 60 ℃, HCl 0.5% reacted for 1 h and 2 mol / L Na_2CO_3 water bath at 85 ℃ shock 5 h, can be effectively removed, and can take into account the removal efficiency and relatively intact terrestrial debris. According to the study, the actual effect of bioclastic debris on particle size should be taken into consideration when analyzing terrigenous detritus sizes for different types of sediment samples, so that a suitable pretreatment scheme should be selected. That is, to ensure that the particle size analysis results of terrestrial detritus are closer to the true distribution, the pretreatment steps of sediment samples are as good as possible, and not all the biogenic components must be removed. For example, when the bio-silica content is less than 2%, the influence on the results of terrigenous particle size analysis is small and may not be removed. In addition, ultrasound can lead to the disintegration of some terrigenous debris and should not be used throughout the process of particle size analysis and pretreatment.