本文關(guān)鍵詞：安徽郎溪黃棕色土-網(wǎng)紋紅土理化性質(zhì)及其古環(huán)境意義　出處：《華東師范大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 黃棕色土 網(wǎng)紋紅土 理化性質(zhì) 風(fēng)成特性 風(fēng)化強度 古環(huán)境意義 郎溪剖面

【摘要】：第四紀(jì)黃棕色土-紅土沉積剖面保留了原始物質(zhì)來源和沉積環(huán)境的相關(guān)信息,對重現(xiàn)和反演我國南方第四紀(jì)時期古氣候古環(huán)境具有重要的意義。本課題組在安徽郎溪縣一處河流階地面上采集了一處由上覆黃棕色土層和下部網(wǎng)紋紅土層組成的二元相剖面。在光釋光(OSL)測年技術(shù)的基礎(chǔ)上,結(jié)合樣品的粒度、元素、磁化率和色度測試,將郎溪XSF剖面與北方黃土及長江中下游沿岸的下蜀黃土進(jìn)行比較。以探討郎溪XSF黃棕色土-網(wǎng)紋紅土剖面的物源及沉積環(huán)境特征,同時對上覆黃棕色土和下部埋藏紅土的理化性狀進(jìn)行分析,比較兩者風(fēng)化成土作用差異,由此解譯出由網(wǎng)紋紅土過渡到黃棕色土所體現(xiàn)的古氣候古環(huán)境演變信息。結(jié)果表明:1)粒度測試表明,黃棕色土和網(wǎng)紋紅土均不含礫石(2mm),砂含量稀少,細(xì)粉砂(2～10μm)為第一眾數(shù)組,10～50μm粗粉砂即"風(fēng)塵基本粒組"含量位居其次,粒度組分特征指示了顯著的風(fēng)積成因特性;粒度組分曲線沿剖面深度垂直方向上均勻變化,說明黃棕色土和埋藏紅土原始物質(zhì)來源的同源性和穩(wěn)定性;隨著剖面深度的變化,網(wǎng)紋紅土的粒度頻率曲線細(xì)顆粒(2μm和2～10μm)處的峰變寬變高,而粗粉砂(10～50μm)處的峰降低,揭示了下部網(wǎng)紋紅土沉積后原位經(jīng)歷的風(fēng)化強度高于黃棕色土;2)元素測試表明,剖面元素組成以常量元素SiO2、Al2O3、TFe2O3(TFe203=Fe2O3+FeO)為主,常量元素組分在剖面內(nèi)隨深度變化分布均勻,說明剖面原始物質(zhì)來源的同源性和穩(wěn)定性;剖面風(fēng)化強度指標(biāo)在剖面上下部變化明顯,隨著剖面SA、SAF值降低,CIA值升高,表明風(fēng)化淋溶作用和脫硅富鋁鐵化作用在逐漸增強。且風(fēng)化強度指標(biāo)與2μm黏粒含量具有很好的可比性,進(jìn)一步說明2μm黏粒含量具有指示剖面風(fēng)化強度的意義。3)磁學(xué)測試表明,黃棕色土磁性增強,網(wǎng)紋紅土與黃棕色土相比具有極低的磁化率值,隨著剖面深度的的變化,網(wǎng)紋層HIRM值上升顯著,表示在細(xì)顆粒的磁鐵礦和磁赤鐵礦向粗顆粒的赤鐵礦和針鐵礦生成轉(zhuǎn)化過程中,磁化率值大大降低,由此反映出網(wǎng)紋紅土發(fā)育于我國南方一個高溫且降水量劇增的時期,風(fēng)化成土作用顯著增強。4)色度測試表明,剖面L*與a*可以很好的對應(yīng),且a*值與黏粒(2μm)含量變化呈明顯正相關(guān)關(guān)系,說明色度具有一定的古氣候代用指標(biāo)的意義。各古氣候代用指標(biāo)在郎溪XSF剖面黃棕色土于網(wǎng)紋紅土之間對比顯著,在網(wǎng)紋紅土向黃棕色土過渡過程中可能蘊藏了一次重要的長江中下游地區(qū)的古氣候轉(zhuǎn)型事件,可以與第四紀(jì)冰川作用以及深海氧同位素曲線階段很好的對應(yīng)。5)光釋光(OSL)測年結(jié)果顯示,黃棕色土發(fā)育于末次冰期,其與網(wǎng)紋紅土交界處處于末次間冰期向末次冰期過渡階段,由網(wǎng)紋紅土向黃棕色土的轉(zhuǎn)變這一現(xiàn)象可能很好的記錄了長江中下游地區(qū)一次由暖濕轉(zhuǎn)向溫涼的古氣候事件。
[Abstract]:In the yellow brown soil clay deposition profile retains the information of the original material sources and sedimentary environment, has important significance to reproduce and inversion of South China during the Quaternary paleoclimate environment. The research group in Anhui Langxi County, a river terrace collected by a overlying yellow brown layer and lower reticulate the clay layer is composed of two phase profile. In optical luminescence (OSL) dating based on technology, combined with the sample size, elements, magnetic susceptibility and chroma test, the XSF of Langxi section and the North Loess and the Yangtze River along the coast of the Xiashu loess were compared. In order to investigate the XSF of Langxi yellow brown soil texture laterite profile provenance and sedimentary environment characteristics, analyzed the physicochemical properties of the overlying clay and buried in yellow brown earth and the lower part of the comparison between Weathering and pedogenesis of differences, thus interpreted by laterite transition to yellow brown The evolution of soil information of paleoclimate and paleoenvironment. The results show that: 1) size test showed that the yellow brown soil and laterite were not gravel sand content (2mm), rare, fine sand (2 ~ 10 m) for the first array, 10 ~ 50 m of coarse silt or dust the basic particle group "content ranks second, grain size characteristics indicate significant aeolian origin characteristics; grain size distribution curve along the vertical direction of uniform depth changes, illustrate the homology and stability of yellow brown soil and red soil buried raw material sources; with the depth profile, fine particle size frequency curve of reticulate red clay (2 m and 2 ~ 10 m) at the peak width becomes high, and coarse silt (10 ~ 50 m) at the peak decreased, reveals the weathering intensity lower after deposition in situ through laterite is higher than that of yellow brown soil; 2) element tests show that with constant element SiO2 Al2O3, TFe2O3 (TFe203=Fe profile elements. 2O3+FeO), major element in profile changes with depth distribution, homogeneity and stability profile shows primitive source; section weathering intensity indexes of lower in profile changes significantly, with a section of SA, SAF decreased, CIA increased, showed that the weathering and dissolution and removal of silicon and aluminum iron. Gradually increased. And the weathering intensity index and 2 m clay content has good comparability, further explains the 2 m clay content has indicated the significance of.3 weathering intensity profile) magnetic test shows that the yellow brown soil magnetic enhancement, the red soil and yellow brown soil texture compared with the very low rate of magnetization and with the depth profile, reticulate layer HIRM increased significantly, said to generate coarse hematite and goethite in fine particles of magnetite and maghemite transformation process, magnetic susceptibility value is greatly reduced, thus reflecting the reticulate red clay The development in South China a high temperature and precipitation increase during weathering pedogenesis significantly enhanced.4) colorimetric test shows that L* and a* profiles can correspond very well, and the value of a* and clay (2 m) showed a significant positive correlation between the content changes of color that has a certain alternative ancient gas when the index. The paleoclimate indicators XSF in Langxi section of yellow brown earth in contrast between laterite significantly, in laterite process to yellow brown earth in the transition is an important paleoclimate in the Yangtze River Delta transformation events can correspond to.5 and fourth Ji Bingchuan and the deep-sea oxygen isotope curve good) optical luminescence (OSL) dating results showed that yellow brown soil developed in the last glacial period, with the junction of Plinthitic red earth in late last interglacial to glacial interglacial transition stage, the reticulate red clay transition to the yellow brown soil The phenomenon may be a good record of an paleoclimate event in the middle and lower reaches of the Yangtze River from warm wet to cool.

【學(xué)位授予單位】：華東師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S151.9;P532

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