本文選題：石筍 + 碳氧穩(wěn)定同位素��； 參考：《西南大學》2015年碩士論文

【摘要】：全新世時期全球氣候變化,是國際全球氣候變化研究計劃的最為重要的內容之一,重建全新世高分辨率的氣候記錄,對于認識氣候系統(tǒng)變化規(guī)律、應對當前面臨的嚴峻氣候和環(huán)境形勢、預測未來氣候變化趨勢有著至關重要的意義。目前全新世氣候演變研究逐漸深入,取得了一些成果,為進一步研究全新世氣候變化奠定了基礎,但是全新世時期的氣候變化驅動機制依然存在爭議。洞穴石筍與黃土、冰芯、樹輪、湖泊沉積、孢粉等氣候重建代用指標相比,具有精確定年、分辨率高、保存氣候環(huán)境記錄完整、分布廣泛、樣品易得且成本低廉等顯著優(yōu)勢,已經成為當前研究古氣候記錄的主力軍之一。本文以長江上游地區(qū)重慶市青木關鎮(zhèn)為研究區(qū)域,利用青木關地區(qū)獅子山洞石筍QM09的25個230Th精確定年和315個碳氧同位素數據重建了0～9.4kaBP期間的高分辨率石筍碳氧同位素的時間序列,結合亞洲季風區(qū)的其他洞穴的石筍記錄,分析石筍氧同位素與全新世時期氣候的響應關系,并討論了全新世內部的氣候波動變化趨勢；利用石筍碳同位素嘗試分析與當時氣候變化、植被變化關系,進而分析人類活動與全新世氣候之間存在的響應關系,全新世時期人與自然環(huán)境之間的關系,目前研究的重點主要側重于自然環(huán)境的變化對人類活動產生的影響,尤其是“4.2ka事件”以來,對人類活動影響自然環(huán)境的研究較為缺乏,深入探討人類活動的影響是本文的重點和創(chuàng)新點,通過探討得出如下結論：(1)獅子山洞石筍QM09高分辨率氧同位素記錄顯示：獅子山洞所處的重慶地區(qū)氣候變化與亞洲季風區(qū)其他地區(qū)氣候變化趨勢基本保持一致,石筍記錄具有可重復性,顯示獅子山洞石筍基本沒有受到區(qū)域因素的影響,研究區(qū)內在6.0～9.4kaBP期間,8180值變化范圍為-9.483%～-11.187%o,平均值為-10.435‰,變化幅度達到1.704%o,氧同位素值整體處于偏負狀態(tài),表明此階段季風整體處于強盛階段,降水豐富；在4.2～6.0kaBP期間,石筍δ18O值變化范圍為-8.874%o-10.762%o,平均值為-9.776‰,變化幅度為1.888%o,顯示石筍δ18O值開始逐漸偏正,但整體還是處于偏負狀態(tài),表明此階段季風整體保持強勢狀態(tài),降水充沛,內部存在季風波動,季風加強和減弱事件交替出現；4.2ka BP以來,石筍δ180值變化范圍為-7.132%～-9.921‰，平均值為-8.538‰,變化幅度為2.789‰,δ18O值顯示已經開始處于偏正狀態(tài),表明季風整體開始減弱,降水逐漸減少。(2)獅子山洞石筍QM09高分辨率碳同位素記錄顯示：獅子山洞石筍QM09的碳同位素在4.5-9.4ka BP期間,碳同位素值變化范圍為-14.555%o～-13.341%o,變化幅度為1.2140‰,平均值為-13.911‰,可以看出碳同位素值基本在-14%o上下波動,整體處于偏負狀態(tài),能夠指示重慶地區(qū)植被覆蓋率較高,植被類型以C3植被為主要植被類型,C4植被相對較少；4.2ka BP以來,碳同位素值變化范圍為-14.403‰～-5.848‰,變化幅度為8.555‰,平均值為-11.260‰,碳同位素值出現強烈波動,整體趨于偏正狀態(tài),指示C3植被覆蓋率明顯下降,自然生態(tài)環(huán)境趨于惡化。(3)4.2ka BP以來,尤其是近2000年來,重慶地區(qū)人類活動的規(guī)模明顯增多和范圍明顯擴大,對自然植被的影響進一步擴大,改變了地表的植物類型,間接影響了土壤有機質和生物量,土壤有機質降低和生物量的減少,使石筍形成的中間環(huán)節(jié),尤其是石筍碳同位素產生變化,使其逐漸偏重,論證了人類活動通過改造地表植被類型會對自然環(huán)境產生影響的結論。
[Abstract]:The global climate change during the Holocene is one of the most important contents of the international global climate change research program. The reconstruction of a Holocene high resolution climate record is of great significance for understanding the changing rules of the climate system, dealing with the severe climate and environmental situation and predicting the trend of climate change in the future. The study of the Holocene climate evolution has been progressively deepening, and some achievements have been obtained, which lay a foundation for further study of the Holocene climate change, but the driving mechanism of climate change in the Holocene is still controversial. The Cave Stalagmite is accurate and accurate in comparison with the climatic reconstruction indicators such as loess, ice core, tree wheel, lake deposition and sporopollen. It has become one of the main forces in the study of paleoclimate records. This paper takes the Chongqing city of Chongqing city in the upper reaches of the Yangtze River as the research area, and uses 25 230Th precise years and 315 carbon and oxygen in the green shoot of the lion cave in the Qinghai Province. The isotopic data reconstructs the time series of high resolution carbon and oxygen isotopes of stalagmite during the period of 0 to 9.4kaBP, combined with the stalagmite records of other caverns in the Asian monsoon region, and analyses the response relationship between the oxygen isotope of the stalagmite and the Holocene epoch, and discusses the trend of the climate change in the Holocene. The relationship between climate change and vegetation change at that time, and then the response relationship between human activity and Holocene climate, the relationship between human and natural environment during the Holocene, the focus of the present study mainly on the effects of natural environment changes on human activities, especially since the "4.2ka event". The research on the influence of the natural environment is relatively short. It is the key and innovation point of this paper. Through the discussion, the following conclusions are drawn: (1) the QM09 high resolution oxygen isotope records of the Stalagmite in the lion cave show that the climate change in the Chongqing region of the lion cave and the climate change trend in other regions of the Asian monsoon region Keeping the same, the stalagmite records are repeatable, showing that the Stalagmite in the lion cave is not affected by regional factors. During the period of 6 ~ 9.4kaBP, the range of 8180 values is -9.483% to -11.187%o, the average value is -10.435 per 1000, the change range is 1.704%o, the oxygen isotope value is in the negative state, indicating the monsoon in this stage. During the period of 4.2 ~ 6.0kaBP, the variation range of the delta 18O value of the stalagmite is -8.874%o-10.762%o, the average value is -9.776 per 1000, the change range is 1.888%o, which shows that the value of the stalagmite Delta 18O begins to be positive, but the whole is still in a negative state, which indicates that the monsoon in this stage remains strong, and the precipitation is abundant and internal exists. The monsoon fluctuation occurred alternately in the monsoon strengthening and weakening events; since 4.2ka BP, the variation range of the delta 180 value of the stalagmite was -7.132% to -9.921 per thousand, the average value was -8.538 per 1000, the change range was 2.789 per thousand, and the delta 18O value showed that the monsoon began to be in the positive state, indicating that the monsoon began to weaken and the precipitation decreased gradually. (2) the high resolution of the stalagmite QM09 in the lion cave. Carbon isotope records show that the carbon isotope of QM09 in the lion cave in 4.5-9.4ka BP, the variation range of carbon isotope value is -14.555%o to -13.341%o, the variation range is 1.2140 per thousand and the average value is -13.911 per 1000. It can be seen that the carbon isotope value fluctuates basically in the upper and lower -14%o, and the whole body is in the negative state, which can indicate the vegetation cover in Chongqing area. The cover rate is higher, the vegetation type is C3 vegetation as the main vegetation type, and the C4 vegetation is relatively less. Since 4.2ka BP, the variation range of carbon isotope value is from -14.403 to -5.848 per thousand, the variation range is 8.555 per thousand, the average value is -11.260 per thousand, the carbon isotope value fluctuates strongly, the whole trend is in the partial positive state, indicating that the vegetation coverage rate of C3 is obviously decreased, naturally the vegetation coverage of C3 is decreased obviously. Nature The ecological environment tends to deteriorate. (3) since 4.2ka BP, especially in recent 2000, the scale of human activities in Chongqing area has increased obviously and its scope is obviously expanded, the influence of the natural vegetation is further expanded, the plant type of the surface is changed, the soil organic matter and the biomass, the decrease of soil organic matter and the decrease of the biomass, make the stalagmite The intermediate links formed, especially the carbon isotopes of stalagmite, make it more and more heavy, demonstrating the conclusion that human activities will affect the natural environment through the transformation of the vegetation types of the surface.

【學位授予單位】：西南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P532

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