湖北高分辨率石笋记录的DO18事件特征
- 1. 浙江师范大学地理与环境科学学院, 浙江金华 321004;
- 2. 南京师范大学地理科学学院, 南京 210023
基金项目:
国家自然科学基金项目(41602350,41602181,41572340);浙江省自然科学基金项目(LY16D010001)
作者简介:
张伟宏,女,1987年出生,博士,讲师,全球气候环境变化,E-mail:zhangwh@zjnu.cn
- 收稿日期:
2017-05-24
- 修回日期:
2017-08-31
- 刊出日期:
2018-08-10
摘要: 研究冰量较大时期千年尺度事件的区域响应和结构特征有助于进一步理解和验证千年尺度事件的驱动机制。基于湖北永兴洞一支石笋的5个高精度230Th年龄和323个氧同位素数据,重建了Dansgaard-Oeschger(DO)18事件发生时高分辨率的东亚水文循环变化的过程和特征。结合同一洞穴另两支石笋记录,发现永兴洞石笋δ18O在~64.7 ka迅速负偏1.5‰,指示在MIS4阶段东亚季风区确实发生了持续时间较短的DO18事件。石笋δ18O结果精确标定了DO18事件的结束时间为~63.0 ka,结束过程呈现出5个百年尺度的季风增强振荡。在形态特征上,不同于格陵兰冰芯DO18事件的快速开始和快速结束(~60 a)的对称变化,季风区DO18事件呈现出快速增强但缓慢结束(持续达1500 a)的显著不对称特征。但是,石笋δ18O与北大西洋温盐环流(AMOC)变化在形态特征和持续时间上高度一致,暗示了AMOC对东亚季风区DO事件的重要调控作用。DO18事件时东亚季风与北大西洋气候的不同结构特征可归于高低纬气候系统对AMOC响应方式的差异。石笋δ18O功率谱结果呈现出208 a、150 a、52 a和14~12 a的变化周期,分别接近于太阳活动的207 a、149 a、57 a和11 a周期,说明在冰量较大的MIS4阶段太阳活动仍控制着东亚季风短尺度的波动。
DO18 Event Depicted by a High-resolution Stalagmite Record from Yongxing Cave, Hubei Province
- 1. College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, China;
- 2. College of Geography Science, Nanjing Normal University, Nanjing 210023, China
Funds:
National Natural Science Foundation of China, No. 41602350, 41602181, 41572340; Zhejiang Provincial Natural Science Foundation of China, No. LY16D010001
- Received Date:
2017-05-24
- Rev Recd Date:
2017-08-31
- Publish Date:
2018-08-10
Abstract: It helps further understand and test forcing mechanisms behind millennial-scale events to decipher their regional responses and structures during the periods of large ice sheets. Using 323 stable oxygen isotope ratios and 5 230Th ages of a stalagmite in Yongxing Cave, central China, we reconstruct a detailed history of the East Asian hydrological cycle during the time span surrounding the Dansgaard-Oeschger (DO) 18 event. The calcite δ18O profile, together with another two stalagmite records from the same cave, shows a rapid decrease of 1.5‰ at~64.7 ka, confirming the occurrence of DO18 in the East Asian monsoon (EAM) region. The ending limb of DO18 in the EAM regime is characterized by five centennial-scale monsoon enhancing events, and finally culminates at~63.0 ka. Divergent from a rapid temperature increasing followed by a similarly rapid cooling (~60 a) back to stadial environments of the Greenland DO18 event, the DO18 event in the monsoon region exhibits a significant asymmetric feature with a sharp EAM strengthening but then a smoothing, lasting 1 500 a, decrease. Nonetheless, our stalagmite δ18O records mirror, in shape and timing, the variations of Atlantic meridional overturning circulation (AMOC) estimated by the ratio of 231Pa/230Th and recovered from the deep western North Atlantic. This similarity suggests that the AMOC played an important role in regulating the DO18 event in the EAM region. On the other hand, the discrepancy in the pattern of DO18 between the EAM and the North Atlantic climate systems can be attributed to the different regional response to the AMOC change in the high-and low-latitude climate systems. Spectral analysis of the stalagmite δ18O record denotes significant cycles at the 90% confidence level at 208, 150, 52 and 14-12 a, close to the previously reported solar cycles at 207, 149, 57 and 11 a. This consistency of cyclical variabilities between the EASM intensity and solar activity might indicate that solar forcing of centennial-and decadal-scale EASM variation still existed during the MIS4 interval with larger ice volumes.
张伟宏, 廖泽波, 陈仕涛, 邵庆丰, 段福才, 朱丽东, 王天阳. 湖北高分辨率石笋记录的DO18事件特征[J]. 沉积学报, 2018, 36(4): 674-683. doi: 10.14027/j.issn.1000-0550.2018.051
ZHANG WeiHong, LIAO ZeBo, CHEN ShiTao, SHAO QingFeng, DUAN FuCai, ZHU LiDong, WANG TianYang. DO18 Event Depicted by a High-resolution Stalagmite Record from Yongxing Cave, Hubei Province[J]. Acta Sedimentologica Sinica, 2018, 36(4): 674-683. doi: 10.14027/j.issn.1000-0550.2018.051
Citation: |
ZHANG WeiHong, LIAO ZeBo, CHEN ShiTao, SHAO QingFeng, DUAN FuCai, ZHU LiDong, WANG TianYang. DO18 Event Depicted by a High-resolution Stalagmite Record from Yongxing Cave, Hubei Province[J]. Acta Sedimentologica Sinica, 2018, 36(4): 674-683. doi: 10.14027/j.issn.1000-0550.2018.051
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