本文選題：巖溶盆地 + 粘土礦物　； 參考：《貴州大學(xué)》2015年碩士論文

【摘要】：貴州威寧麻窩山巖溶盆地受西南印度洋和東南太平洋兩種季風(fēng)的共同影響對(duì)氣候響應(yīng)較敏感。盆地內(nèi)沉積物記錄了沉積環(huán)境演變信息,是研究氣候變化的極佳場(chǎng)所。本文以貴州威寧麻窩山巖溶盆地為研究對(duì)象,采用了鉆探取樣、X射線衍射、粒度分析和鉆孔剖面中主量元素和微量元素含量變化分析等手段,分析了剖面沉積物的礦物學(xué)特征以及地球化學(xué)元素特征。探討了該地區(qū)40ka BP以來(lái)的古氣候演變,初步得到以下結(jié)論。(1)剖面4沉積物礦物主要由粘土礦物(38%~72%)、方解石(0%~39%)、石英(10%~55%)以及長(zhǎng)石(0%~3%)等組成,其中粘土礦物含量最多且波動(dòng)較大,方解石在灰白色湖沼層含量較高,可能與該層出現(xiàn)生物殼體有關(guān)。依據(jù)粘土礦物總量和方解石含量可將剖面劃分為(a-i)9層。(2)粘土礦物組成主要為伊利石/蒙脫石混層礦物(30%~75%)和綠泥石(10%~45%),其次是伊利石(10%)和高嶺石(5%~20%),少數(shù)樣品含蒙脫石。綠泥石與伊/蒙混層礦物相對(duì)含量呈此消彼長(zhǎng)的關(guān)系,且垂向上具有較明顯的變化規(guī)律,出現(xiàn)多個(gè)冷暖—干濕旋回。伊利石結(jié)晶度指數(shù)和化學(xué)指數(shù)相較于其他粘土礦物指標(biāo)更為敏感,在剖面的底部出現(xiàn)較大幅度的波動(dòng),存在兩個(gè)冷暖—干濕小旋回。(3)地球化學(xué)元素研究表明,剖面Ti/A1比值、Zr、Rb元素在垂向上均呈規(guī)律變化,且剖面間具有較好的一致性,與剖面顏色變化相吻合。Ti/Al高值,對(duì)應(yīng)溫暖濕潤(rùn)的氣候環(huán)境,Ti/A1低值,對(duì)應(yīng)寒冷干燥的氣候環(huán)境。生物殼體層對(duì)應(yīng)的Ti/Al高值,表明當(dāng)時(shí)的氣候比較溫暖,降水較豐富,適合生物的生長(zhǎng)繁殖。(4)Zr/Rb與粒度具有重要的環(huán)境意義,即Zr/Rb值低,湖泊沉積物中細(xì)顆粒含量較多,可能指示化學(xué)風(fēng)化作用較強(qiáng)的溫度較高,降水豐富的氣候環(huán)境;Zr/Rb值高,湖盆沉積物中粗粒礦物相對(duì)較多,可能指示化學(xué)風(fēng)化作用相對(duì)較弱,物理風(fēng)化占主導(dǎo)地位的溫度較低,降水量少的氣候環(huán)境。(5)通過(guò)全樣礦物組成、粘土礦物組成以及地球化學(xué)元素特征綜合分析,可將研究區(qū)剖面劃分為4個(gè)階段,3個(gè)冷暖—干濕大循環(huán),其中第Ⅰ、Ⅱ、Ⅲ階段分別包含2個(gè)冷暖—干濕的小循環(huán)。
[Abstract]:The Mawushan karst basin in Weining Guizhou is more sensitive to the climate response under the influence of the two monsoons in the southwest Indian Ocean and the southeast Pacific Ocean. The sediment in the basin records the evolution information of sedimentary environment and is an excellent place to study climate change. In this paper, the Mawushan karst basin in Weining, Guizhou Province, is studied by means of X-ray diffraction, particle size analysis and variation analysis of the main elements and trace elements in the borehole profile. The mineralogical characteristics and geochemical elements of the sediments in the profile are analyzed. The paleoclimate evolution since 40ka BP in this area is discussed, and the following conclusions are obtained preliminarily. 4) the sediment minerals in section 4 are mainly composed of clay minerals 38 and 722, calcite 39, quartz 1010555 and feldspar 0 ~ 3 ~ 3), among which clay minerals are the most abundant and fluctuate. The content of calcite is high in the grayish-white lake, which may be related to the appearance of biological shell in this layer. According to the total amount of clay minerals and the content of calcite, the profile can be divided into 9 layers. 2) the composition of clay minerals is mainly composed of Illite / montmorillonite mixed layer mineral (30 + 7575) and chlorite 1010454545. The next is Illite 104545) and kaolinite 52020. A few samples contain montmorillonite. The relative content of chlorite and the minerals in the Iraq / montmorillonite layer fluctuates in the same direction, and there are obvious changes in vertical direction, and there are many cycles of cold, warm and dry wet and wet. Illite crystallinity index and chemical index are more sensitive than other clay mineral indexes, and there are large fluctuations at the bottom of the profile, and there are two cold, warm, dry and wet cycles. The ratio of Ti/A1 to Rb in profile changes regularly in vertical direction, and there is good consistency between sections, which coincides with the color change of section, the high value of Ti / Al, the low value of Tip / A1 in warm and humid climate environment, and the cold and dry climate environment. The high value of Ti/Al in the shell layer indicates that the climate was warm and the precipitation was abundant. It is of great environmental significance to fit the growth and reproduction of organisms. The ZrR / RB and particle size are of great environmental significance, that is, the Zr/Rb value is low and the fine grain content in lacustrine sediments is more than that in lacustrine sediments. It may indicate that the temperature with strong chemical weathering is higher, the climatic environment with abundant precipitation has a high Zr / R _ b value, the coarse-grained minerals in the sediments of the lake basin are relatively more, and the chemical weathering is relatively weak, and the temperature dominated by physical weathering is relatively low. The climatic environment with less precipitation can be divided into four stages by the comprehensive analysis of the mineral composition, clay mineral composition and geochemical element characteristics of the study area, in which the first, the second, the cold, warm, dry and wet cycles, are divided into four stages. Stage 鈪，

本文編號(hào)：1814543