皖南红土剖面粘土矿物组合与伊利石晶化程度研究
发布时间：2018-11-13 20:30
【摘要】：安徽省位于中国华东地区,是暖温带和亚热带的过渡地区,该区地处红黄土交接带,既有第四纪红土出露,又有下蜀黄土分布,是揭示黄土沉积和红土发育的敏感地带。本文选取的研究区域位于皖南地区,在宣城市宣州区(XZ)和郎溪县(LX)各选取一个第四纪红土剖面,通过研究第四纪红土的元素地球化学特征、风化指标、色度、粘土矿物组合和伊利石晶化度,探讨其对第四纪红土形成环境的指示意义。主要获得结论如下：(1)宣州和郎溪第四纪红土不同层次粘土矿物的组合基本相似,但存在细微差别：剖面上部的黄棕色土层,是形成于末次冰期的下蜀黄土层,粘土矿物组成主要为伊利石、高岭石和2：1型的蛭石；均质红土和网纹红土粘土矿物以伊利石和高岭石为主,不含蛭石。但网纹层下部,伊利石峰变宽缓,出现伊利石蚀变后形成的伊利石-蒙脱石混层矿物,反映了剖面下部红土形成环境更加湿热。(2)用X-射线衍射(XRD)法分析主要粘土矿物组合,并利用伊利石d001(1.0nm)衍射峰的半高宽测算伊利石的IC值。两剖面伊利石IC值在0.4～0.7之间,伊利石结晶程度处于高与中等之间。各层伊利石IC值存在显著差异。第四纪红土剖面从黄棕色土→均质红土→网纹红土,伊利石IC值升高,晶化度降低,反映了红土自上而下湿热程度的增加。网纹红土伊利石蚀变和分解,还与网纹形成过程长期剧烈的地下水活动有关。本研究第四纪红土伊利石IC值显著高于黄土高原黄土(0.3～0.4)、古土壤(0.35～0.5)和第三纪红土(0.4～0.5),表明南方红土风化强,伊利石结晶程度低。(3)宣州剖面IC值与风化淋溶系数(Ba)、K2O/TiO2、Na2O/TiO2、MgO/TiO2的负相关性达显著水平(p0.05)。郎溪剖面IC值与硅铁铝率(Saf)、风化淋溶系数(Ba)、K2O/TiO2、Na2O/TiO2的负相关性均达显著水平(p0.05)。XZ和LX剖面K2O/TiO2值与IC值的相关性最密切。这可能由于伊利石层间含有较多钾,钾流失与伊利石蚀变、晶体的分解有密切联系。充分表明第四纪红土伊利石IC值,可有效反映红土风化强度。宣州和郎溪土壤剖面的色度测量结果表明,剖面L*值自上而下是逐渐降低,而a*值和b*值却呈相反趋势逐渐升高。但在研究剖面下部,网纹层由于铁质流失,土层发白,L*值偏高；a*值和b*值也局部出现波谷。第四纪红土剖面自上而下,伊利石IC升高,与红土风化强度自上而下增加吻合。红土伊利石IC值,与红土粒度、元素地球化学等指标反映的古气候信息一致。因此,红土IC值可作为古气候指标之一,反映红土形成时期古气候的演变。
[Abstract]:Anhui Province, located in East China, is a transitional area between warm temperate zone and subtropical zone. The region is located in the red loess intersecting zone. It is a sensitive zone for revealing the loess deposition and the development of laterite, both in Quaternary red soil outcrop and in Xiashu loess distribution. The research area selected in this paper is located in the south of Anhui Province. A Quaternary laterite profile is selected in Xuanzhou District, Xuancheng District, Xuanzhou District and (LX) County, Langxi County, respectively. The element geochemical characteristics, weathering index, chromaticity of the Quaternary laterite are studied. The clay mineral assemblage and the crystallization degree of Illite are discussed to indicate the formation environment of Quaternary laterite. The main conclusions are as follows: (1) the assemblages of clay minerals in different layers of the Quaternary laterite in Xuanzhou and Langxi are basically similar, but there are slight differences: the yellowish-brown soil layer in the upper part of the section is formed in the lower Shu loess layer in the last glacial period. The clay minerals are mainly composed of Illite, kaolinite and 2:1 vermiculite. Illite and kaolinite are the main clay minerals of homogenous red soil and reticulated red soil, without vermiculite. However, in the lower part of the netted layer, the peak of Illite becomes wider and slower, and the mixed layer of Illite and montmorillonite is formed after the alteration of Illite. The results show that the formation environment of laterite in the lower section is more humid and hot. (2) the main clay mineral assemblages are analyzed by X-ray diffraction (XRD) method, and the IC value of Illite is calculated by using the half-maximum width of the D001 (1.0nm) diffraction peak of Illite. The IC value of Illite in the two sections is between 0.4 and 0.7, and the crystallization degree of Illite is between high and medium. The IC values of Illite in different layers were significantly different. In the Quaternary laterite profile, the IC value of Illite increased and the crystallization degree decreased from the yellow-brown soil to the homogeneous laterite, reflecting the increase of the degree of moisture and heat from the top to the bottom of the laterite. The alteration and decomposition of Illite in reticulated red earth is also related to the long term intense groundwater activity during the formation of reticulated red soil. The IC value of Illite in Quaternary red soil is significantly higher than that in loess, paleosol and Tertiary red soil, which indicates that the weathering of red soil in southern China is stronger than that in loess plateau (0. 3 ~ 0. 4), paleosol (0. 35 ~ 0. 5) and Tertiary red soil (0. 4 ~ 0. 5). The crystallization degree of Illite is low. (3) the negative correlation between the IC value of Xuanzhou section and weathering leaching coefficient (Ba), K _ 2O / TIO _ 2 / Na _ 2O _ 2 / TIO _ 2 / MgO / TIO _ 2 is significant (p0.05). The negative correlation between IC value of Langxi section and (Saf), weathering leaching coefficient (Ba), K _ 2O _ 2 / TIO _ 2 / Na _ 2O _ 2 / TIO _ 2 was significant (p0.05). XZ and K2O/TiO2 value of LX profile were most closely correlated with IC value). This may be due to the existence of more potassium between the layers of Illite, and the loss of potassium is closely related to the alteration of Illite and the decomposition of crystals. The results show that the IC value of Quaternary laterite Illite can effectively reflect the weathering strength of laterite. The colorimetric measurements of soil profiles in Xuanzhou and Langxi show that the values of L* of the profiles decrease gradually from top to bottom, but the values of a * and b * increase gradually. However, in the lower part of the study section, the net layer is whitened due to the loss of iron, the value of L * is higher, and the values of a * and b * also appear local troughs. The IC of Illite increased from top to bottom in Quaternary laterite profile, which coincided with the increase of weathering strength of laterite from top to bottom. The IC value of the laterite Illite is consistent with the paleoclimate information reflected by the red soil granularity and element geochemistry. Therefore, the IC value of red soil can be used as one of the paleoclimate indexes to reflect the paleoclimate evolution during the formation of laterite.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P577;P534.63
[Abstract]:Anhui Province, located in East China, is a transitional area between warm temperate zone and subtropical zone. The region is located in the red loess intersecting zone. It is a sensitive zone for revealing the loess deposition and the development of laterite, both in Quaternary red soil outcrop and in Xiashu loess distribution. The research area selected in this paper is located in the south of Anhui Province. A Quaternary laterite profile is selected in Xuanzhou District, Xuancheng District, Xuanzhou District and (LX) County, Langxi County, respectively. The element geochemical characteristics, weathering index, chromaticity of the Quaternary laterite are studied. The clay mineral assemblage and the crystallization degree of Illite are discussed to indicate the formation environment of Quaternary laterite. The main conclusions are as follows: (1) the assemblages of clay minerals in different layers of the Quaternary laterite in Xuanzhou and Langxi are basically similar, but there are slight differences: the yellowish-brown soil layer in the upper part of the section is formed in the lower Shu loess layer in the last glacial period. The clay minerals are mainly composed of Illite, kaolinite and 2:1 vermiculite. Illite and kaolinite are the main clay minerals of homogenous red soil and reticulated red soil, without vermiculite. However, in the lower part of the netted layer, the peak of Illite becomes wider and slower, and the mixed layer of Illite and montmorillonite is formed after the alteration of Illite. The results show that the formation environment of laterite in the lower section is more humid and hot. (2) the main clay mineral assemblages are analyzed by X-ray diffraction (XRD) method, and the IC value of Illite is calculated by using the half-maximum width of the D001 (1.0nm) diffraction peak of Illite. The IC value of Illite in the two sections is between 0.4 and 0.7, and the crystallization degree of Illite is between high and medium. The IC values of Illite in different layers were significantly different. In the Quaternary laterite profile, the IC value of Illite increased and the crystallization degree decreased from the yellow-brown soil to the homogeneous laterite, reflecting the increase of the degree of moisture and heat from the top to the bottom of the laterite. The alteration and decomposition of Illite in reticulated red earth is also related to the long term intense groundwater activity during the formation of reticulated red soil. The IC value of Illite in Quaternary red soil is significantly higher than that in loess, paleosol and Tertiary red soil, which indicates that the weathering of red soil in southern China is stronger than that in loess plateau (0. 3 ~ 0. 4), paleosol (0. 35 ~ 0. 5) and Tertiary red soil (0. 4 ~ 0. 5). The crystallization degree of Illite is low. (3) the negative correlation between the IC value of Xuanzhou section and weathering leaching coefficient (Ba), K _ 2O / TIO _ 2 / Na _ 2O _ 2 / TIO _ 2 / MgO / TIO _ 2 is significant (p0.05). The negative correlation between IC value of Langxi section and (Saf), weathering leaching coefficient (Ba), K _ 2O _ 2 / TIO _ 2 / Na _ 2O _ 2 / TIO _ 2 was significant (p0.05). XZ and K2O/TiO2 value of LX profile were most closely correlated with IC value). This may be due to the existence of more potassium between the layers of Illite, and the loss of potassium is closely related to the alteration of Illite and the decomposition of crystals. The results show that the IC value of Quaternary laterite Illite can effectively reflect the weathering strength of laterite. The colorimetric measurements of soil profiles in Xuanzhou and Langxi show that the values of L* of the profiles decrease gradually from top to bottom, but the values of a * and b * increase gradually. However, in the lower part of the study section, the net layer is whitened due to the loss of iron, the value of L * is higher, and the values of a * and b * also appear local troughs. The IC of Illite increased from top to bottom in Quaternary laterite profile, which coincided with the increase of weathering strength of laterite from top to bottom. The IC value of the laterite Illite is consistent with the paleoclimate information reflected by the red soil granularity and element geochemistry. Therefore, the IC value of red soil can be used as one of the paleoclimate indexes to reflect the paleoclimate evolution during the formation of laterite.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P577;P534.63
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