兰州大学机构库 >资源环境学院
过去13万年以来河北珍珠洞和陇南白龙洞石笋碳氧同位素记录
Alternative TitleStalagmite carbon and oxygen isotopic records over the past 130 ka,from Zhenzhu Cave and Bailong Cave
李云霞
Thesis Advisor饶志国 ; 高永利
2018-12-12
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Degree Discipline自然地理学
Keyword河北珍珠洞 陇南白龙洞 洞穴石笋 碳氧同位素 过去13万年以来 环流系统 环境演变
Abstract古气候变化研究已成为了解过去全球气候变化规律和预测未来气候变化的重要手段之一。过去几十年,广大学者已利用不同的地质载体开展了卓有成效的古气候变化研究,尤其是近二十年来,洞穴沉积物凭借其高精度绝对定年、高分辨率、多指标、广泛分布等优势,已成为开展古气候研究的重要地质载体之一。然而,我国东部季风区的石笋氧同位素作为亚洲夏季风强度的指示器,在近年来面临诸多争议,而我国北方地区,长时间尺度的石笋同位素记录鲜有发表,不仅限制了我们对区域气候变化规律的理解,也阻碍了对亚洲夏季风强度演变历史的认识。 本论文主要以河北平山县珍珠洞的ZZ1石笋和陇南康县白龙洞的BY39石笋为主要研究材料,基于高精度的U-Th绝对定年数据(分别为50和27个),和高分辨率的石笋碳、氧同位素结果(分别为2490和593对),建立了珍珠洞过去13万年以来和白龙洞末次冰期期间的石笋碳、氧同位素记录;同时为了更好地认识相关古气候代用指标的指示意义,基于将今论古的原则,我们开展了为期两年(2012.04-2014.04)的珍珠洞洞穴现代监测工作,包括洞外现代大气降水、洞内滴水以及洞内相关参数监测工作。基于以上工作的开展和分析,我们初步获得了以下几点认识: (1) 基于为期两年的河北珍珠洞洞外现代大气降水的监测结果和陇南白龙洞地区的在线模拟大气降水同位素数据,分析结果表明:在月际尺度和年际尺度上,现代大气降水同位素与降水量和温度的关系皆不显著;故而,珍珠洞和白龙洞区域大气降水同位素并不能简单地归因为降水量或温度的影响,可能还会受到其他因素的影响,如水汽源地的变化; (2) 河北珍珠洞洞内滴水监测结果显示:洞内滴水氢、氧同位素在监测期间,变化幅度极小,未有季节变化趋势特征,但其绝对值的分布和洞外大气降水同位素的平均值较为接近;这一结果说明,珍珠洞洞内滴水可以继承大气降水同位素的信号,但由于受到上覆岩层均质化过程(平滑过程)的影响,其滴水同位素记录的是多年或以上时间尺度的大气降水同位素信号; (3) 河北珍珠洞洞内相关参数监测结果显示:珍珠洞洞内温度和相对湿度相对恒定,但其洞内CO2浓度具有明显的季节变化特征,说明珍珠洞洞内CO2浓度变化敏感响应于外界气候因素的变化,尤其是与降水量的关系更为紧密; (4) 现代观测结果及与黄土碳同位素记录的对比分析表明,白龙洞BY39和珍珠洞ZZ1石笋碳同位素主要受控于相对湿度控制的植被覆盖度的变化,是一个相对更加直接和敏感的夏季风降水量变化的指示器;白龙洞BY39和珍珠洞ZZ1石笋氧、碳同位素变化幅度的不一致,暗示其石笋氧同位素的相对偏正偏负不能作为亚洲夏季风降水量(强度)多寡的绝对衡量指标; (5) 白龙洞BY39石笋碳、氧同位素记录结果显示,二者在时间相位变化特征上表现出较好的一致性,且成功捕捉到3次Heinrich事件(H3、H4、H5)和14个DO旋回事件,与北半球高纬度地区的相关气候记录表现出一致地快速波动特征。与区域其他相关气候记录对比发现:在末次冰期期间,BY39石笋氧同位素记录与其他石笋氧同位素记录具有较为一致的时空变化特征,然而在氧同位的绝对值和序列整体变化幅度上具有区域差异性,具体表现:在东西方向上,位于相对内陆的BY39石笋氧同位素值更为偏负且序列的整体变化幅度也偏大,这可能与水汽传输路径有关;而南北方向上,西南地区的石笋氧同位素绝对值更为偏负,这可能与印度季风和东亚季风的主要水汽来源不同有关。此外,BY39石笋碳同位素记录与临近的黄土剖面中的有机碳记录、粒度记录和磁化率记录对比结果显示,这些记录间有着较为一致的变化特征,进一步证实了石笋碳同位素记录作为夏季风强度或降水量指标的可靠性; (6) 河北珍珠洞ZZ1石笋碳、氧同位素记录结果显示二者在相位变化特征上具有相对一致性,皆表现出冰阶—间冰阶的时间尺度上存在快速波动特征,同时又叠加着千年—百年时间尺度的高频波动变化。与区域其他气候记录对比显示,ZZ1石笋氧同位素记录与我国南方同时段的其他石笋氧同位素记录的变化特征具有较好的一致性;而ZZ1石笋碳同位素记录与临近的黄土无机碳同位素记录、磁化率和粒度指标记录有着一致的变化趋势; (7) 整体而言,过去13万年以来,珍珠洞和白龙洞石笋氧、碳同位素记录在时间序列上表现出较好的一致性,但是在变化趋势和幅度上则表现出明显的差异;石笋氧、碳同位素记录的一致和不一致性,反映了降水量和降水同位素对大气环境格局调整的差异性响应。
Other AbstractKnowledge of past climate change covering different timescales provides a precious foundation for understanding past and modeling future states of regional and global climate. Over the past several decades, scientists have obtained a lot of valuable paleoclimatic information from various geological archives, such as ice cores, marine sediments, loess-paleosoil sections, lacustrine sediments, tree rings, and so on. During the past two decades, depended on the development of high precision U/Th dating technique, taking the advantages of multi-proxy, high resolution, continuous or semi-continuous deposition, and wide distribution, stalagmites have been increasingly adopted to reconstruct paleoclimatic change history. However, the indicative significance of oxygen isotopes of stalagmite (δ18Os) in the monsoonal regions of China remains controversial, and there are few long-term records of stalamite that covering glacial/interglacial have been published in monsoonal North China.Here, two stalagmites, namely ZZ1 and BY39 (collected from Zhenzhu Cave in Pingshan County, Hebei Province, and Bailong Cave in Kang County, Gansu Province, respectively), have been studied. Based on precisely 230Th age data (50 and 27 dates respectively), the high resolution stalagmite carbon isotoic (δ13Cs) and δ18Os records (2490 and 593 data pairs respectively) covering the past 130 ka have been obtained. For the interpretation of the obtained stalatmite δ13Cs and δ18Os records, modern observations covering a period of two years (April 2012 to April 2014) have been conducted in and out Zhenzhu Cave. Finally, the following conclusion remarks have been summarized, based on the above-mentioned works.(1) The monitoring results from the outside of Zhenzhu Cave demonstrated that, on monthly and inter-annual timescales, the correlations between oxygen and hydrogen isotopes of local precipitation (δ18Op and δDp) and corresponding temperature and precipitation amount were not significant, impling both the “temperature effect” and “precipitation amount effect” were not applicable for the interepretation of local δ18Op and δDp variations.  (2) The monitoring results from Zhenzhu Cave demonstrated that there were no apparently seasonal variations in the oxygen and hydrogen isotopes of drip water (δ18Od and δDd) in Zhenzhu Cave. Over the period of two years, the δ18Od and δDd data in Zhenzhu Cave were nearly constant, with the absolute values close to the average values of local δ18Op and δDp data in the outside of Zhenzhu Cave, impling that after a relatively long-term (for example, severarl years) “buffering or smoothing effect”, the local δ18Op and δDp signals could be inherited by δ18Od and δDd data.   (3) Both the temperature and relative humidity in Zhenzhu Cave were nearly constant over the observational period of two years. However, the corresponding concentration of CO2 in Zhenzhu Cave showed apparently and significantly seasonal variations, demonstrating the CO2 concentration in Zhenzhu Cave responsed sensitively to the outside envrironmental factors, especially the variations of precipitation amount.   (4) The δ13Cs and δ18Os records from BY39 that covering 27-58 ka BP showed roughly in phase variations with obvious differences in change amplitude. Both the BY39 δ13Cs and δ18Os data record 3 Heinrich events (H3, H4 and H5) and 14 DO events. The spatial δ18Os records comparison between BY39 and other stalagmites from monsoonal China demonstrated similar change patterns with different absolute values and change magnitudes. Specially, in East-West direction (~33° N), the BY39 δ18Os values were more depleted with relatively larger change magnitude, implying the relatively longer transportation path of vapor for Bailong Cave which is located in more inland site. In North-South direction, δ18Os records from Southwest China are more depleted than those from East Asian monsoonal regions, which is quite possibly resulted from the different major vapor sources for Indian summer monsoonal region and East Asian summer monsoonal region. On the other hand, the BY39 δ13Cs record is consistent with other records from the Chinese Loess Plateau, such as organic carbon isotopic composition, grain size, magnetic susceptibility, which have been widely adopted as indicators of the East Asian summer monsoon intensity or precipitation amount.   (5) Similary, the ZZ1 δ13Cs and δ18Os records showed roughly in phase variations, both characterized by glacial/interglacial variations and abrupt millennial-timescale climate events. The ZZ1 δ18Os record is consistent with the other stalagmite δ18Os records from monsoonal South China. However, the ZZ1 δ13Cs is more consistent with other records from the Chinese Loess Plateau, such as records of inorganic carbon isotopic compositions, grain sizes, magnetic susceptibilities, which have been widely adopted as indicators of the East Asian summer monsoon intensity or precipitation amount.    (6) Generally, over the past 130 ka, the stalagmite δ13Cs and δ18Os records from Zhenzhu Cave and Bailong Cave showed roughly in phase variations, but obvious change trends and magnitudes, especially for the records of MIS3 from Zhenzhu Cave. As above-mentioned, due to the stalagmite δ13Cs records from both Zhenzhu Cave and Bailong Cave are more reliable indicator of East Asian summer monsoon intensity or monsoonal precipitation amount, we therefore concluded that stalagmite δ18Os records from these two caves cannot be adopted as direct indicator of East Asiam summer monsoon intensity; the in phase variations of stalagmite δ13Cs and δ18Os records from these two caves with different change trends and magnititudes revealed the different responses of precipitation amount and precipitation δ18Op to the adjustments of general atmospheric circulaitons in monsoonal China.
Pages137
URL查看原文
Language中文
Document Type学位论文
Identifierhttp://ir.lzu.edu.cn/handle/262010/344198
Collection资源环境学院
Affiliation资源环境学院
First Author AffilicationCollege of Earth Environmental Sciences
Recommended Citation
GB/T 7714
李云霞. 过去13万年以来河北珍珠洞和陇南白龙洞石笋碳氧同位素记录[D]. 兰州. 兰州大学,2018.
Files in This Item:
There are no files associated with this item.
Related Services
Recommend this item
Bookmark
Usage statistics
Export to Endnote
Altmetrics Score
Google Scholar
Similar articles in Google Scholar
[李云霞]'s Articles
Baidu academic
Similar articles in Baidu academic
[李云霞]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[李云霞]'s Articles
Terms of Use
No data!
Social Bookmark/Share
No comment.
Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.