本文關(guān)鍵詞： 大堡礁 碳酸鹽 石英 有機(jī)質(zhì) 紅度　出處：《中國地質(zhì)大學(xué)（北京）》2014年博士論文　論文類型：學(xué)位論文

【摘要】：氣候變化及其對人類生存環(huán)境影響的問題對于人類的生存和發(fā)展至關(guān)重要。探索古氣候變化的動(dòng)力成因機(jī)制，可以預(yù)測未來氣候變化趨勢成。研究末次冰期-間冰期南半球低緯海洋海平面及氣候變化的歷史，對于揭示第四紀(jì)晚期南極冰蓋變化及其導(dǎo)致的全球氣候環(huán)境變化具有重要的指示意義，而相關(guān)研究十分有限。因此，本文研究了IODP325航次的沉積巖芯柱礦物學(xué)和地球化學(xué)特征，并將其與南極Vostok冰芯古氣候階段進(jìn)行對比。采用了綜合分析方法，包括：不平衡鈾系（U-Th）定年法、X射線粉晶衍射方法、總碳、總無機(jī)碳和總有機(jī)碳含量分析、沉積物光譜分析（亮度、紅度和黃度）。 研究結(jié)果表明，澳大利亞大堡礁海域海平面變化對南極冰蓋增加或消融變化響應(yīng)敏感。所研究的沉積巖芯柱覆蓋時(shí)間長達(dá)15萬年:在140-116ka BP期間，為末次冰期發(fā)生之前的暖期，冰川融化，海平面較高。沉積物紅度增加，說明該時(shí)期大堡礁海域及沿岸溫度較高、降雨量及其導(dǎo)致的入海徑流較大，隨之入海的石英等礦物也增多，形成較低的碳酸鹽/石英含量比值；隨著全球氣候進(jìn)入末次冰期，盡管也有冷暖變化，但整體上，大堡礁海域海平面較低。在116-73ka BP期間，沉積物紅度較低，陸源輸入較少，大堡礁海域海洋古生產(chǎn)力較低，導(dǎo)致沉積物有機(jī)質(zhì)含量較低；在73-58ka BP期間，大堡礁海域沿岸為冷干期，海平面也較低，該時(shí)期M0058A沉積巖芯主要由砂構(gòu)成；在58-30ka BP期間，大堡礁海域降雨轉(zhuǎn)多、氣候較為濕潤，但碳酸鹽/石英含量比值較低，陸源輸入物質(zhì)較多，或?qū)е铝溯^高的海洋古生產(chǎn)力，從而使沉積物具有高的有機(jī)碳含量；在30-13ka BP期間，沉積物紅度較高，陸源的營養(yǎng)物質(zhì)較多，導(dǎo)致總有機(jī)碳水平較高。但大量的陸源砂質(zhì)物質(zhì)輸入，，導(dǎo)致了碳酸鹽/石英比值較低；13ka BP以來，末次冰期結(jié)束，全球進(jìn)入末次冰期后期，氣溫逐漸增高，冰川融化，降水增多，海平面增高，陸源營養(yǎng)物質(zhì)增多，導(dǎo)致沉積紅度增高、有機(jī)質(zhì)含量增加。同時(shí)海平面增高，大堡礁海域水深增加，水動(dòng)力水平較低，利于碳酸鹽沉淀、不利于石英等陸源物質(zhì)運(yùn)移，導(dǎo)致該處的碳酸鹽/石英比值增高。上述研究結(jié)果為全面評價(jià)近15萬年以來大堡礁海域氣候環(huán)境變化提供了數(shù)據(jù)基礎(chǔ)。
[Abstract]:The problem of climate change and its impact on human living environment is very important for human survival and development. The history of the last glacial to interglacial Southern Hemisphere low latitude ocean sea level and climate change can be predicted. It is of great significance to reveal the late Quaternary Antarctic ice sheet changes and the resulting global climate and environmental changes, and the relevant studies are very limited. In this paper, the mineralogical and geochemical characteristics of the sedimentary core column of the IODP325 voyage are studied and compared with the paleoclimate stage of the Vostok ice core in Antarctica. A comprehensive analysis method is used. It includes: unbalanced uranium series U-Thage dating method, X-ray powder diffraction method, total carbon, total inorganic carbon and total organic carbon content analysis, sediment spectrum analysis (brightness, redness and yellowness). The results show that. Sea level changes in the Great Barrier Reef, Australia, are sensitive to changes in the Antarctic ice sheet. The sedimentary core column studied covers a period of 150,000 years: 140-116 ka BP. During the warm period before the last ice age, the glacier melted, the sea level was higher, and the redness of the sediment increased, which indicated that the temperature of the Great Barrier Reef and the coastal area was higher, and the rainfall and the runoff into the sea caused by it were larger. The amount of quartz and other minerals entering the sea also increased, forming a lower carbonate / quartz content ratio. With the global climate entering the last glacial period, although there are also some changes in cold and warm, the sea level in the Great Barrier Reef is lower. During the period of 116-73 ka BP, the red degree of sediment is lower and the input of land source is less. The marine paleoproductivity in the Great Barrier Reef is low, which leads to the low content of organic matter in the sediments. During the period of 73-58ka BP, the coast of the Great Barrier Reef was cold dry and the sea level was lower. During this period, the M0058A sedimentary core was mainly composed of sand. During the period of 58-30ka BP, the Great Barrier Reef area had more rainfall and wetter climate, but the carbonate / quartz content ratio was lower, and there were more terrestrial inputs, which may lead to higher marine paleoproductivity. Thus, the sediment has a high organic carbon content; During the period of 30-13ka BP, the red degree of sediment is higher and the nutrient content of terrestrial source is more, which leads to the higher level of total organic carbon, but a large amount of terrestrial sand material input, which results in lower carbonate / quartz ratio. Since 13ka BP, the end of the last glacial epoch and the end of the last glacial epoch, the temperature gradually increased, the glacier melted, the precipitation increased, the sea level increased, and the nutrition of land source increased, which led to the increase of sedimentation red degree. At the same time, the sea level increases, the water depth in the Great Barrier Reef increases, and the hydrodynamic level is lower, which is conducive to carbonate precipitation and is not conducive to the migration of continental materials such as quartz. These results provide a data basis for the comprehensive evaluation of climate and environmental changes in the Great Barrier Reef area in the past 150,000 years.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)（北京）
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：P532;P736.21

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相關(guān)期刊論文 前1條

1 王紹武;;D/O循環(huán)與H事件[J];氣候變化研究進(jìn)展;2011年06期

本文編號：1453307