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孢粉浓缩物作为孢粉学研究的基础和前提,其纯度直接影响到孢粉学研究结论的准确性。干旱区湖泊沉积物孢粉浓缩物中残留的不溶矿物颗粒,对孢粉鉴定、分析和测年等造成干扰。明确不溶颗粒的矿物成分,探讨孢粉提取过程中化学反应作用机制,对完善于旱区湖泊沉积物孢粉浓缩物提取方法有重要意义。本文选取石羊河下游终端湖——猪野泽地区沙坑井(SKJ)和九驼梁(JTL)剖面湖泊沉积物及相应层位孢粉浓缩物,进行矿物成分对比研究,结果显示:全样和孢粉浓缩物的矿物成分均以石英和硅酸盐类矿物为主;孢粉浓缩物中矿物组成更为多样,硅酸盐矿物种类与全样差异较大,这可能由于石英与硅酸盐类矿物和氢氟酸反应,在溶液中产生了大量硅酸根、含氟金属络合阳离子和金属阳离子所导致。两种阳离子通过与硅酸根结合,或与原有硅酸盐矿物发生置换反应,使孢粉浓缩物中出现了全样中不存在的硅酸盐或碳酸盐矿物。孢粉浓缩物中较多的矿物种类也可能与样品总量减少有关,因为微量矿物的含量会因其他矿物的大量减少而增加,从而在浓缩物中得以表现。此外,全样矿物与氢氟酸反应后会生成硅凝胶物质,有可能会阻碍酸与样品的进一步反应,使孢粉浓缩物中存在未能完全反应的石英和少量碳酸盐类矿物。因此,干旱区湖泊沉积物孢粉提取过程中,应当慎用氢氟酸,在充分分散样品后,选择适当比重的重液浮选去除大部分石英和硅酸盐类,再使用氢氟酸多次处理,是完善干旱区湖泊沉积物孢粉浓缩物提取方法的有效途径。
As the basis and precondition of sporopollen research, the purity of sporopollen concentrate directly affects the accuracy of palynology conclusion. The insoluble mineral particles remaining in the pollen concentration of lacustrine sediments in the arid region interfere with the identification, analysis and dating of pollen. It is of great significance to clarify the mineral composition of insoluble particles and to explore the mechanism of chemical reaction in the process of pollen extraction, which is of great significance to perfection of the extraction method of pollen concentration in lacustrine sediments. In this paper, lake sediments and the corresponding layers of pollen concentration in the lake terminal-lake Yeoze area of the Shiyang River and the lacustrine sediments of the Jiu Tunel (JTL) section were selected for mineral comparisons. The results showed that: And sporopollen concentrates are dominated by quartz and silicate minerals; the sporopollen concentrates are more diverse in mineral composition and silicate mineral species are quite different from the whole sample, which may be due to quartz and silicic acid Salt minerals and hydrofluoric acid reaction, in the solution produced a large number of silicate, fluoride metal complex cation and metal cation caused. The two cations combine with silicate, or with the original silicate mineral substitution reaction, so that the spore powder concentrate appeared in the sample does not exist silicate or carbonate minerals. The more mineral species in sporopollen concentrates may also be related to the decrease in total sample volume, as the trace mineral content will increase as a result of the drastic reduction of other minerals and thus be present in the concentrate. In addition, the whole sample of minerals and hydrofluoric acid reaction will generate a silicone gel material, it may hinder the further reaction of acid and the sample, so that there is incomplete reaction of spore powder concentrate quartz and a small amount of carbonate minerals. Therefore, hydrofluoric acid should be used with caution in spore-polluted lake sediment deposition in arid areas. After the samples have been fully dispersed, most of the quartz and silicates should be removed by heavy-liquid flotation with appropriate specific gravity, and then hydrofluoric acid The secondary treatment is an effective way to improve the extraction method of sporopollen concentrate in lacustrine sediments in arid area.