本文選題：草海　切入點：早更新世　出處：《華東師范大學》2015年碩士論文　論文類型：學位論文

【摘要】：人類出現(xiàn)在第四紀并且在這一時期快速發(fā)展,因此進行第四紀研究具有十分重要的意義。一般來說,在較小的時間尺度下研究環(huán)境演變,就需要更準確、分辨率更高的測年手段。不同測年方法存在不同的優(yōu)點和局限性,而電子自旋共振測年法以其測年范圍廣幾乎涵蓋整個第四紀而被廣泛應(yīng)用。草海盆地是典型的構(gòu)造巖溶盆地,地處云貴高原東部。其沉積物來源于周圍山體,加上沒有遠源河流,記錄著盆地的演化。因此,它是研究云貴高原東緣第四紀演化的一個不可多得的場所。本研究以貴州威寧草海地區(qū)湖相地層的陳選屯剖面為研究對象,進行電子自旋共振定年確定沉積年代,結(jié)合青藏高原隆升史以及分析色度、粒度、磁性參數(shù)和地球化學元素等環(huán)境代用指標含量和縱向分布特征,對草海的古環(huán)境特征和演化進行初步推測和還原。研究主要得出以下結(jié)論：(1)草海湖相沉積地層的ESR測年結(jié)果顯示為距今1.16-1.871Ma,與之前的古地磁測定結(jié)果相比更為準確。測年結(jié)果對應(yīng)時代為早更新世的青藏運動C幕,此時草海仍受西南季風影響,推測為溫暖濕潤氣候。(2)草海湖相沉積地層的色度結(jié)果表明,L*(亮度值)較高,a*(紅度值)和b*(黃度值)較低。據(jù)此可以推測,草海當時的是一個溫度較低,氣候溫暖濕潤,以還原作用為主的一個深湖環(huán)境。(3)草海湖相地層粒度結(jié)果顯示,其粒度分布相對集中,以粒徑較小的粘土和細粉砂為主,剖面整體分選較差。故指示古環(huán)境為河流或湖泊,且應(yīng)處于較為濕潤的高水位時期。(4)草海湖相地層磁性結(jié)果表明,剖面的頻率磁化率和剩磁均指示其暖濕的古環(huán)境。然而,磁化率指示其干冷的古環(huán)境。研究表明,物質(zhì)的磁化率不一定能完整地反映它在真實環(huán)境中的全部磁學特性,存在環(huán)境信息丟失的狀況。本研究不考慮磁化率的指示結(jié)果。因此,磁性參數(shù)指示是暖濕古環(huán)境,與色度及粒度一致。(5)草海湖相地層的元素地球化學特征選取B、Sr、Mg/Al、Sr/Ba、Sr/Cu、B/Ga進行多指標古環(huán)境分析。結(jié)果均顯示其形成時為氣候溫濕的深湖沉積環(huán)境。(6)ESR測年結(jié)果顯示的氣候特征與環(huán)境代用指標指示的氣候特征基本吻合,說明ESR定年較為準確具有一定的科學參考價值。
[Abstract]:Humans appeared in the Quaternary and developed rapidly during this period, so Quaternary research is of great significance. Generally speaking, it is more accurate to study the evolution of the environment at a relatively small time scale. Different dating methods have different advantages and limitations, while electron spin resonance dating method is widely used because of its wide range of dating covering the entire Quaternary. The Caohai Basin is a typical tectonic karst basin. It is located in the eastern part of the Yungui Plateau. Its sediment originates from the surrounding mountains and there are no distant rivers, which records the evolution of the basin. It is a rare place to study the Quaternary evolution of the eastern margin of the Yunnan-Guizhou Plateau. In this study, the Chen Xiantun section of the lacustrine strata in the Huining Caohai area, Guizhou Province, was used as an object of study to determine the sedimentary age by means of electron spin resonance dating. In combination with the uplift history of the Qinghai-Tibet Plateau and the analysis of the contents and longitudinal distribution characteristics of environmental substitution indexes such as chroma, granularity, magnetic parameters and geochemical elements, In this paper, the paleoenvironmental characteristics and evolution of the Caohai are preliminarily inferred and reduced. The main conclusions are as follows: 1: 1) the ESR dating of the Caohai lacustrine sedimentary strata is 1.16-1.871 Ma, which is more accurate than the previous paleomagnetic measurements. The dating results correspond to the early Pleistocene Qinghai-Tibet movement, At this time, Caohai is still affected by the southwest monsoon, which is supposed to be a warm and humid climate. 2) the chrominance of Caohai lacustrine sedimentary strata shows that the luminance values are higher in the Caohai Lake than the red ones (redness values) and bong (yellowness values). It can be inferred that, At that time, Caohai was a deep lacustrine environment with low temperature, warm and humid climate and a deep lake environment dominated by reduction. The results showed that the granularity distribution of Caohai lacustrine facies was relatively concentrated, mainly of clay and fine silt with smaller particle size. The magnetic properties of Caohai Lake facies show that the frequency susceptibility and remanence of the section indicate its warm and wet paleoenvironment. Magnetic susceptibility indicates its dry and cold paleoenvironment. Studies have shown that the magnetic susceptibility of matter does not necessarily reflect all of its magnetic properties in real environments. There is a loss of environmental information. This study does not consider the indication of magnetic susceptibility. Therefore, the magnetic parameter indication is warm and wet paleoenvironment. Element geochemistry characteristics of Caohai lacustrine facies are analyzed by multiparameter paleoenvironment analysis using BPS-SrSr-Mg-Al / Al / Sr-ba-r-SrCu-B / Ga. The results show that the formation time of Caohai lacustrine facies is a climate special characteristic of ESR dating results of deep lake sedimentary environment with warm and wet climate. The climatic characteristics indicated by the indicator of environmental substitution are basically consistent with each other. It shows that ESR dating is more accurate and has certain scientific reference value.
【學位授予單位】：華東師范大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P534.631

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