陆生蜗牛壳体高分辨率的稳定氧同位素记录与季节的干湿变化  

SEASONAL DRY-WET VARIABILITY RECORDED BY HIGH-RESOLUTION STABLE OXYGEN ISOTOPE IN LAND SNAIL SHELL

作　　者：王蜜 David L DETTMAN 倪观忠 胡涵 余子莹 陈京平 丁璇 王鑫[1] WANG Mi;David L DETTMAN;NI Guanzhong;HU Han;YU Ziying;CHEN Jingping;DING Xuan;WANG Xin(College of Earth and Environmental Sciences,Lanzhou University,Lanzhou 730000,Gansu;Department of Geosciences,University of Arizona,Tucson,AZ,85721)

机构地区：[1]兰州大学资源环境学院,甘肃兰州730000 [2]Department of Geosciences,University of Arizona,Tucson,AZ,85721

出　　处：《第四纪研究》2022年第4期1159-1167,共9页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:42072211)资助。

摘　　要：季节变化是气候系统的基本特征,然而受研究材料和方法所限,陆相沉积序列中难以获得古气候的季节变化信息。文章选择兰州地区,在旱季和雨季分别采集两个现生条华蜗牛(Cathaica fasciola),通过沿壳体生长轴高分辨率取样分析,发现兰州地区旱季生长的蜗牛壳体稳定氧同位素组成(δ^(18)O)整体偏正、雨季生长的壳体显著偏负,单个壳体内部δ^(18)O的波动幅度捕获了季节干湿变化信号。综合现代观测、黄土高原其他地区记录、通量平衡模式等证据,提出蜗牛壳体δ^(18)O旱季偏正,主要受蒸发效应和温度影响,蒸发效应可能更为重要;蜗牛壳体δ^(18)O雨季偏负,主要受降水氧同位素组成和温度影响。蜗牛壳体高分辨率的稳定氧同位素研究在揭示亚洲古季风季节干湿变化方面有巨大应用潜力,系统的现代过程研究是推动该方法进一步发展的关键所在。Seasonality is one of the key parameters that determine climate characters,however,most of the available paleoclimate records from terrestrial environment are average signal of year to thousands of years and lack seasona resolution. In this work,we collected two shells of living land snail in Lanzhou( 35. 95°N,104. 13°E) during dry season and wet season. In order to minimize the effects of behavior differences on the shell record,we focused on one land snail genus( Cathaica fasciola) . Then we drilled carbonate powder samples( 50 ~ 100 μg) along the growth axis( from apex to lip) of each shell for high-resolution stable oxygen isotopic analysis. Our results indicate that the stable oxygen isotopic values( δ^(18)O) of land snail shells are relatively higher in dry season and relatively lower in wet season. Combination with modern observations,published datasets from the Chinese Loess Plateau,and the flux balance models,we propose that the higher δ^(18)O values is mainly linked to the substantial evaporation processes of ambient water and lower temperature during dry season,whilst the lower δ^(18)O values is related to the lower δ^(18)O values of rainfall and higher temperature during wet season. We argue that high-resolution stable oxygen isotopic study of land snail shells has great potential for reconstructing seasonal wet-dry variability of Asian monsoon in geological time,and highlight the importance of modern observations for further improve the technique.

关 键 词：蜗牛壳体 稳定氧同位素 季节性 干湿变化 

分 类 号：P597.2[天文地球—地球化学] P532[天文地球—地质学]