皖南紅土剖面粘土礦物組合與伊利石晶化程度研究
發(fā)布時間：2018-11-13 20:30
【摘要】：安徽省位于中國華東地區(qū),是暖溫帶和亞熱帶的過渡地區(qū),該區(qū)地處紅黃土交接帶,既有第四紀(jì)紅土出露,又有下蜀黃土分布,是揭示黃土沉積和紅土發(fā)育的敏感地帶。本文選取的研究區(qū)域位于皖南地區(qū),在宣城市宣州區(qū)(XZ)和郎溪縣(LX)各選取一個第四紀(jì)紅土剖面,通過研究第四紀(jì)紅土的元素地球化學(xué)特征、風(fēng)化指標(biāo)、色度、粘土礦物組合和伊利石晶化度,探討其對第四紀(jì)紅土形成環(huán)境的指示意義。主要獲得結(jié)論如下：(1)宣州和郎溪第四紀(jì)紅土不同層次粘土礦物的組合基本相似,但存在細(xì)微差別：剖面上部的黃棕色土層,是形成于末次冰期的下蜀黃土層,粘土礦物組成主要為伊利石、高嶺石和2：1型的蛭石；均質(zhì)紅土和網(wǎng)紋紅土粘土礦物以伊利石和高嶺石為主,不含蛭石。但網(wǎng)紋層下部,伊利石峰變寬緩,出現(xiàn)伊利石蝕變后形成的伊利石-蒙脫石混層礦物,反映了剖面下部紅土形成環(huán)境更加濕熱。(2)用X-射線衍射(XRD)法分析主要粘土礦物組合,并利用伊利石d001(1.0nm)衍射峰的半高寬測算伊利石的IC值。兩剖面伊利石IC值在0.4～0.7之間,伊利石結(jié)晶程度處于高與中等之間。各層伊利石IC值存在顯著差異。第四紀(jì)紅土剖面從黃棕色土→均質(zhì)紅土→網(wǎng)紋紅土,伊利石IC值升高,晶化度降低,反映了紅土自上而下濕熱程度的增加。網(wǎng)紋紅土伊利石蝕變和分解,還與網(wǎng)紋形成過程長期劇烈的地下水活動有關(guān)。本研究第四紀(jì)紅土伊利石IC值顯著高于黃土高原黃土(0.3～0.4)、古土壤(0.35～0.5)和第三紀(jì)紅土(0.4～0.5),表明南方紅土風(fēng)化強(qiáng),伊利石結(jié)晶程度低。(3)宣州剖面IC值與風(fēng)化淋溶系數(shù)(Ba)、K2O/TiO2、Na2O/TiO2、MgO/TiO2的負(fù)相關(guān)性達(dá)顯著水平(p0.05)。郎溪剖面IC值與硅鐵鋁率(Saf)、風(fēng)化淋溶系數(shù)(Ba)、K2O/TiO2、Na2O/TiO2的負(fù)相關(guān)性均達(dá)顯著水平(p0.05)。XZ和LX剖面K2O/TiO2值與IC值的相關(guān)性最密切。這可能由于伊利石層間含有較多鉀,鉀流失與伊利石蝕變、晶體的分解有密切聯(lián)系。充分表明第四紀(jì)紅土伊利石IC值,可有效反映紅土風(fēng)化強(qiáng)度。宣州和郎溪土壤剖面的色度測量結(jié)果表明,剖面L*值自上而下是逐漸降低,而a*值和b*值卻呈相反趨勢逐漸升高。但在研究剖面下部,網(wǎng)紋層由于鐵質(zhì)流失,土層發(fā)白,L*值偏高；a*值和b*值也局部出現(xiàn)波谷。第四紀(jì)紅土剖面自上而下,伊利石IC升高,與紅土風(fēng)化強(qiáng)度自上而下增加吻合。紅土伊利石IC值,與紅土粒度、元素地球化學(xué)等指標(biāo)反映的古氣候信息一致。因此,紅土IC值可作為古氣候指標(biāo)之一,反映紅土形成時期古氣候的演變。
[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.
【學(xué)位授予單位】：浙江師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：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.
【學(xué)位授予單位】：浙江師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P577;P534.63
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