本文選題：可可西里湖泊 + 表層沉積物��； 參考：《蘭州大學》2015年碩士論文

【摘要】：在古氣候演變重建過程中,環(huán)境替代指標的認識是其中重要的研究內(nèi)容之一。目前記錄海洋、湖泊、冰川、黃土等環(huán)境信息載體的古環(huán)境指標主要有地球化學、地球生態(tài)、地球物理等,其中沉積物的元素組成特征是應(yīng)用較廣的指標之一。但多年的實踐證明,元素作為古環(huán)境重建的地球化學指標,在指示環(huán)境意義方面仍存在許多亟待解決的問題。青藏高原因其獨特的地理位置和地質(zhì)背景,對東亞季風的形成以及全球氣候系統(tǒng)具有特殊的影響作用；其不僅有類型眾多的湖泊,而且湖泊沉積物記錄了豐富的氣候變化信息,對認識東亞季風的形成機理、全球的古氣候系統(tǒng)演化具有重要意義。因此,本文以青藏高原北緣可可西里地區(qū)現(xiàn)代湖泊(水洼)為研究對象,通過對沉積物中元素和湖泊水介質(zhì)、類型等綜合分析,利用研究區(qū)淡水湖、微咸水湖、咸水湖及鹽湖中表層沉積物粒度參數(shù)特征、礦物組成、元素地球化學特征,探討金屬元素的遷移富集規(guī)律,從而深入了解元素指標的環(huán)境指示意義,對古環(huán)境重建指標提供一些基礎(chǔ)背景資料和理論。主要結(jié)論如下：1、研究區(qū)淡水湖泊主要有取樣點kkx1-5和kkx1-13兩個湖泊。粒徑大于63μm的砂在湖泊中占沉積物總量的70-90%左右,以滾動及跳躍方式遷移,且主要以跳躍遷移方式為主：粉砂(4-64 μm)占表層沉積物總量的20-10%左右,以懸浮遷移為主,部分粒徑較大的粉砂表現(xiàn)出以跳躍方式遷移的特性；湖泊中粘土組分含量較少,主要以懸浮方式遷移。粒度組成特征反映了青藏高原湖泊表層沉積物或為多源的特性,研究區(qū)流域總體上為水動力強的暫時性水流。2、微咸水湖泊在研究區(qū)分布比例較多,按照湖泊表層沉積物粒度參數(shù)特征,將研究區(qū)微咸水湖泊分為三大類：第一類湖泊主要包括kkx1-4,7,25取樣點處的湖泊。粒徑大于63μm的粗粒占表層沉積物總量的70%左右,主要以滾動方式遷移；粉砂在湖泊中的遷移以跳躍方式為主,約占表層沉積物總量的25%左右；粘土主要表現(xiàn)為懸浮遷移,在湖泊中含量分布較少。第二類湖泊包括kkx1-2,9,10,12,14,22,24,26取樣點處共8個湖泊,粒徑大于350μm的組分主要以滾動方式遷移至湖泊,在湖泊表層沉積物中約占10%左右；粒徑處于63-350 gm的沉積物約占沉積物總量的40-70%,以跳躍方式遷移；粉砂主要以跳躍和懸浮方式遷移；粘土在此類湖泊中含量較少,約10%左右,主要通過懸浮方式進行遷移。第三類湖泊主要包括取樣點kkxl-3,11,15,21,23,27共六個湖泊。其中,粒徑大于250μm的組分主要以滾動方式遷移,占表層沉積物總量的10%左右；粒徑位于63-250μm的組分主要通過滾動和跳躍的方式進行遷移,在湖泊表層沉積物中占有較大的比例,約20-30%；粉砂主要是以懸浮和跳躍的方式進行遷移,占表層沉積物總量的50%左右；粘土主要以懸浮方式遷移至湖泊,在湖泊環(huán)境中占有約20%。3、咸水湖主要包括kkxl-18,19兩個湖泊,以滾動方式進入兩湖泊的組分較少,占其表層沉積物總量的5%左右,其顆粒物粒徑大于250μm；跳躍遷移的組分在kkxl-18湖泊中占其表層沉積物總量的85%左右,在kkxl-19湖泊中約占表層沉積物總量的15%；以懸浮方式遷移的組分,在kkxl-18湖泊中占表層沉積物總量的10%左右,在kkxl-19湖泊表層沉積物中占有80%左右。4、在研究區(qū)湖泊表層沉積物中,元素Ca、Mg、Sr的分布受湖泊環(huán)境中碳酸鹽分布的影響作用明顯；元素Si主要受石英顆粒分布的影響,水動力的變化控制了其在湖泊內(nèi)的分布。常微量元素的分布受沉積物粒徑組分的影響較大。5、對各湖泊表層沉積物中常微量元素UCC標準化后,研究區(qū)湖泊表層沉積物中As元素在各類湖泊中異常富集,其次Ca、Mg、Cr、Pb、V等元素富集,而K、Na元素在各類湖泊中明顯虧損,元素Al和Rb在淡水湖表層沉積物中虧損,而在微咸水-咸水表層沉積物中則保持平衡。說明了青藏高原湖泊的地表徑流補給較快、水體較冷,化學風化作用較弱。湖泊水體在演化過程中元素K、Na因溶解性強而長期存在,湖泊向高鹽度方向發(fā)展。
[Abstract]:In the process of paleoclimate evolution reconstruction, the understanding of environmental alternative indicators is one of the most important research contents. The paleoenvironmental indicators that record marine, lake, glacier, loess and other environmental information carriers are mainly geochemistry, geo ecology and Geophysics, among which the characteristics of the element composition of the sediments are one of the more widely used indicators. Many years of practice have proved that as a geochemical index for the reconstruction of the paleoenvironment, there are still many problems to be solved in the direction of the environmental significance. The unique geographical location and geological background of the Qinghai Tibet Plateau have special effects on the formation of the East Asian monsoon and the global climate system; it not only has many types of lakes. And lake sediments have recorded abundant information on climate change, which is of great significance to the understanding of the formation mechanism of the East Asian monsoon and the evolution of the global paleoclimate system. Therefore, this paper takes the modern Lakes (water pools) in the cocoa Xili area of the northern margin of the Qinghai Tibet Plateau as the research object, through the synthesis of the elements and lakes in the sediments and the types of the lakes. By analyzing the characteristics of the grain size parameters, mineral composition and elemental geochemical characteristics of the surface sediments in the freshwater lake, brackish water lake, saltwater lake and Saline Lake, the migration and enrichment of metal elements is discussed, so as to understand the environmental indicator significance of the element index, and provide some basic background data and theory for the reconstruction of the ancient environment. The main conclusions are as follows: 1, the main freshwater lakes in the study area are two lakes of kkx1-5 and kkx1-13. The sand with a particle size of 63 mu m is about 70-90% of the total amount of sediment in the lake, and is moved by the way of rolling and jumping, and mainly in the way of jumping migration. The silt (4-64 mu m) accounts for about 20-10% of the total amount of the surface sediments, and is suspended in suspension. Mainly, the silt with large part of grain size is characterized by leaping. The content of clay components in the lake is less, mainly by suspension mode. The characteristics of the grain size composition reflect the characteristics of the surface sediments of the Qinghai Tibet plateau lake or the characteristics of multi source. The basin in the study area is a temporary water.2 with a strong hydrodynamic force, and the brackish water lakes are in the lake in the study area. The distribution ratio of the study area is more. According to the characteristics of the grain size parameters of the surface sediments of the lake, the brackish water lakes in the study area are divided into three major categories: the first kind of lake mainly includes the lake at the kkx1-4,7,25 sampling point. The coarse grains with the grain size of 63 Mu account for about 70% of the total amount of the surface sediments, mainly by rolling mode, and the migration of silt in the lake There is about 25% of the total amount of surface sediments in the way of jumping. Clay mainly shows suspended migration, and the content distribution is less in the lake. The second kinds of lakes include 8 lakes at kkx1-2,9,10,12,14,22,24,26 sampling point, and the components of the grain size greater than 350 Mu are mainly migrated to the lakes by the rolling square, and about the surface sediments of the lake. About 10%, the sediment with a diameter of 63-350 GM, which accounts for about 40-70% of the total amount of sediment, is migrated in a hopping way, and the silt is mainly transported by leaping and leaping, and clay is less in this kind of lake, about 10%, mainly by suspension mode. The third types of Lakes mainly include a total of six sampling points of kkxl-3,11,15,21,23,27. Among them, the components of the particle size greater than 250 u m are mainly migrated by rolling, accounting for about 10% of the total amount of the surface sediments, and the components with a diameter of 63-250 mu m are mainly migrated by rolling and jumping, which occupies a large proportion in the surface sediments of the lake, about 20-30%, and the silt is mainly moved by levitating and jumping. Shifting, accounting for about 50% of the total surface sediment total, clay mainly migrated to lakes in a suspension mode, occupied about 20%.3 in the lake environment, mainly including two lakes in the saltwater lake, and less in the two lakes in the rolling way, accounting for 5% left right of the total surface sediments, and the particle size of its particles was more than 250 mu m; the jump migration group was more than 250. The kkxl-18 Lake accounts for about 85% of the total surface sediments in the lake and about 15% of the total surface sediments in the kkxl-19 lake. The component of the suspended mode is about 10% of the total surface sediments in the kkxl-18 lake, and about 80%.4 in the surface sediments of the kkxl-19 lake. In the surface sediments of the study area, the elements of the lake surface sediments are in the study area. The distribution of Ca, Mg and Sr is influenced by the distribution of carbonate in the lake environment; element Si is mainly influenced by the distribution of quartz particles. The variation of hydrodynamic forces control its distribution in the lake. The distribution of the trace elements is greatly influenced by the grain size of the sediments, and the normal trace elements UCC in the surface sediments of each lake are standardized after.5. The As elements in the lake surface sediments of the study area are enriched in various lakes, followed by the enrichment of Ca, Mg, Cr, Pb, V and other elements, while K, Na elements are obviously lost in all kinds of lakes, and the elements Al and Rb are lost in the surface sediments of fresh water lake, while the balance in the salt water and salt water surface sediments shows the surface runoff of the Qinghai Tibet plateau lake. The recharge is faster, the water body is cold and the chemical weathering is weak. In the evolution process of the lake water, the elements K and Na exist for a long time because of the strong solubility, and the lake develops to the high salinity direction.
【學位授予單位】：蘭州大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P595;P343.3

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