利川地区14.4ka BP以来石笋记录的气候变化研究
发布时间：2019-05-20 04:49
【摘要】：近年来,人类社会对全球气候变化日益关注,洞穴石笋因其高精度定年和和高分辨率特征,在古气候变化研究中占据重要地位。本文基于玉龙洞石笋(编号TCL)9个U/Th绝对年龄和787个δ180测试数据建立了利川地区近14.4ka BP以来的东亚季风变化序列。玉龙洞石笋TCL的δ180气候演化序列与亚洲季风区其他洞穴石笋记录在千年至百年尺度上表现出整体的一致性,说明亚洲地区洞穴石笋δ180受同一气候影响因子驱动,石笋δ180记录可以较好的反映千年至百年尺度上的亚洲季风气候变化。石笋TCL的δ13C值主要反映了研究区域植被丰度的变化,具有明显的周期性特征,大致可分为4个旋回。功率谱分析结果显示,813C具有2000年左右的显著周期,可能反映了研究区域局域环境的特殊变化规律。石笋TCL的灰度和δ13C曲线存在良好的相关性,二者在总体变化趋势上基本一致,呈现出明显的峰谷对应特征。石笋碳同位素与沉积岩性的良好对应关系,证实了这种代用指标的可靠性,同时也表明了两者具有共同的驱动机制：当研究区域降雨量充沛,植物茂盛,土壤CO2产率增高时、δ13C负偏；此时土壤有机质微粒含量升高,灰度值亦增大；反之亦然。石笋TCL的微量元素比Sr/Ca和Ba/Ca与δ13C之间也存在较好的相关关系,表明微量元素比值的变化可以作为古气候与古环境重建记录的有效补充。在14.4ka BP以来,研究区域最为显著的变化出现在5.6～4.2ka BP时段,此时Sr/Ca和Ba/Ca大幅度下降形成一显著低谷,而δ13C和灰度均表现出相似的变化特征,说明降水量、植被减少,局域环境明显恶化。玉龙洞石笋8180记录了与北大西洋冷事件相对应的“4.2ka BP弱季风事件”,持续时间为4.4ka～4.1ka BP,呈现出“两峰三谷”结构类型。同时,玉龙洞记录显示东亚夏季风自中世纪暖期(约1ka BP)开始呈现显著的增强趋势,不同于印度季风自小冰期结束后(约0.4ka BP)显著增强。说明近千年以来的亚洲夏季风增强可能受到不同驱动因子的影响。
[Abstract]:In recent years, human society has paid more and more attention to global climate change. Cave stalagmites play an important role in the study of paleoclimate change because of their high precision dating and high resolution characteristics. Based on the absolute age of 9 U/Th and 787 未 180 test data of stalagmites in Yulongdong (No. TCL), the East Asian monsoon variation sequence in Lichuan area since 14.4ka BP is established in this paper. The 未 180 climate evolution sequence of Yulong cave stalagmites TCL is consistent with the records of other cave stalagmites in Asian monsoon region from 1000 to 100 years, which indicates that 未 180 of cave stalagmites in Asia is driven by the same climate influencing factors. Stalagmites 未 180 records can well reflect the Asian monsoon climate change on the scale of 1000 to 100 years. The 未 13 C value of stalagmites TCL mainly reflects the change of vegetation abundance in the study area and has obvious periodic characteristics, which can be divided into four cycles. The results of power spectrum analysis show that 813 C has a significant period of about 2000 years, which may reflect the special variation of the local environment in the study area. There is a good correlation between the gray scale and 未 13 C curve of stalagmites TCL, which are basically the same in the overall change trend, showing obvious peak and valley corresponding characteristics. The good correspondence between carbon isotopes and sedimentary lithology of asparagus confirms the reliability of this alternative index, and also shows that the two have a common driving mechanism: when the rainfall is abundant, the plants are luxuriant and the yield of CO2 in soil is increased, 未 13 C negative deviation; At this time, the content of soil organic matter particles increased, and the gray value also increased, and vice versa. There is also a good correlation between trace elements in stalagmites TCL and Sr/Ca and Ba/Ca and 未 13 C, which indicates that the change of trace element ratio can be used as an effective supplement to the record of paleoclimate and paleoenvironment reconstruction. Since 14.4ka BP, the most significant change in the study area has occurred in the 5.6~4.2ka BP period. At this time, Sr/Ca and Ba/Ca decreased significantly to form a significant trough, while 未 13 C and gray scale showed similar characteristics. It shows that precipitation, vegetation decrease and local environment deteriorate obviously. Yulongdong stalagmites 8180 recorded the "4.2ka BP weak monsoon event" corresponding to the North Atlantic cold event, and the duration of the "two peaks and three valleys" structure type for 4.4ka~4.1ka BP,. At the same time, Yulong cave records show that the East Asian summer monsoon has shown a significant enhancement trend since the medieval warm period (about 1ka BP), which is different from that of the Indian monsoon since the end of the Little Ice Age (about 0.4ka BP). It is suggested that the enhancement of the Asian summer monsoon in recent thousands of years may be affected by different driving factors.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P532
本文编号：2481364
[Abstract]:In recent years, human society has paid more and more attention to global climate change. Cave stalagmites play an important role in the study of paleoclimate change because of their high precision dating and high resolution characteristics. Based on the absolute age of 9 U/Th and 787 未 180 test data of stalagmites in Yulongdong (No. TCL), the East Asian monsoon variation sequence in Lichuan area since 14.4ka BP is established in this paper. The 未 180 climate evolution sequence of Yulong cave stalagmites TCL is consistent with the records of other cave stalagmites in Asian monsoon region from 1000 to 100 years, which indicates that 未 180 of cave stalagmites in Asia is driven by the same climate influencing factors. Stalagmites 未 180 records can well reflect the Asian monsoon climate change on the scale of 1000 to 100 years. The 未 13 C value of stalagmites TCL mainly reflects the change of vegetation abundance in the study area and has obvious periodic characteristics, which can be divided into four cycles. The results of power spectrum analysis show that 813 C has a significant period of about 2000 years, which may reflect the special variation of the local environment in the study area. There is a good correlation between the gray scale and 未 13 C curve of stalagmites TCL, which are basically the same in the overall change trend, showing obvious peak and valley corresponding characteristics. The good correspondence between carbon isotopes and sedimentary lithology of asparagus confirms the reliability of this alternative index, and also shows that the two have a common driving mechanism: when the rainfall is abundant, the plants are luxuriant and the yield of CO2 in soil is increased, 未 13 C negative deviation; At this time, the content of soil organic matter particles increased, and the gray value also increased, and vice versa. There is also a good correlation between trace elements in stalagmites TCL and Sr/Ca and Ba/Ca and 未 13 C, which indicates that the change of trace element ratio can be used as an effective supplement to the record of paleoclimate and paleoenvironment reconstruction. Since 14.4ka BP, the most significant change in the study area has occurred in the 5.6~4.2ka BP period. At this time, Sr/Ca and Ba/Ca decreased significantly to form a significant trough, while 未 13 C and gray scale showed similar characteristics. It shows that precipitation, vegetation decrease and local environment deteriorate obviously. Yulongdong stalagmites 8180 recorded the "4.2ka BP weak monsoon event" corresponding to the North Atlantic cold event, and the duration of the "two peaks and three valleys" structure type for 4.4ka~4.1ka BP,. At the same time, Yulong cave records show that the East Asian summer monsoon has shown a significant enhancement trend since the medieval warm period (about 1ka BP), which is different from that of the Indian monsoon since the end of the Little Ice Age (about 0.4ka BP). It is suggested that the enhancement of the Asian summer monsoon in recent thousands of years may be affected by different driving factors.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P532
【参考文献】
相关期刊论文 前1条
1 汪永进,吴江滢,许汉奎,穆西南;南京汤山洞穴石笋稳定同位素指示的气候与环境意义[J];地质学报;2000年04期
，本文编号：2481364
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