王旭^1,,
崔琳琳¹,
翟吉璇²,
丁仲礼¹
1. 中国科学院地质与地球物理研究所, 中国科学院新生代地质与环境重点实验室, 北京 100029
2. 北京十一学校, 北京 100039

基金项目: 国家重点研究发展计划项目（批准号：2017YFA0603400）和国家自然科学基金项目（批准号：41572163）共同资助


详细信息

作者简介: 王旭, 男, 44岁, 研究员, 同位素地球化学与古环境研究, E-mail: xuking@mail.iggcas.ac.cn

中图分类号: P593;P534.63

收稿日期:2020-12-28
修回日期:2021-03-20
刊出日期:2021-07-30

Clumped isotopes in land snail shell carbonate and its significance for paleoclimate study

WANG Xu^1,,
CUI Linlin¹,
ZHAI Jixuan²,
DING Zhongli¹
1. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029
2. Beijing National Day School, Beijing 100039


MSC: P593;P534.63

--> Received Date: 28 December 2020
Revised Date: 20 March 2021
Publish Date: 30 July 2021


摘要
摘要:碳酸盐团簇同位素是国际上新近开发的地质温度计，可以精确重建过去的温度变化。蜗牛壳体化石是研究古气候的理想载体，其种属组合和碳、氧同位素组成分析提供了丰富的气候环境信息。在此基础上，蜗牛壳体团簇同位素分析势必会为古温度定量重建提供强有力手段。然而，相关研究却开展得较少，值得我们投入更多的精力去推动该领域的发展。本研究首先介绍了碳酸盐团簇同位素及其制备和分析方法，以便古气候研究者对新兴研究手段有所了解。然后，对蜗牛壳体团簇同位素的研究历史与现状进行了梳理，指出了研究中尚存的不解问题，并对未来的研究进行了展望。总之，尽管野外采集蜗牛的团簇同位素温度系统地高于生长季温度，但二者之间存在较好的线性关系，所以蜗牛壳体团簇同位素可以用来重建蜗牛生长季节的环境温度。然而，在相同地点蜗牛壳体团簇同位素存在种属差异（如华蜗牛团簇同位素温度比巴蜗牛高3℃左右），所以精确重建古温度需要建立属一级蜗牛壳体团簇同位素-温度转换方程。同时，通过团簇同位素温度和蜗牛壳体δ¹⁸O计算出的蜗牛体液δ¹⁸O可以反映降水的氧同位素信息，是研究古水文循环的重要指标。黄土地层中蜗牛壳体化石团簇同位素研究显示我国北方末次冰期的夏季温度要比现代低7~10℃左右。虽然该温度变幅有待进一步研究确证，但它们至少为冰期-间冰期温度变化提供了独立证据和有用参考。鉴于显口多点螺（Punctum orphana）化石在黄土地层中连续赋存且最可能被广泛用于古温度重建研究，我们未来可优先建立该种属蜗牛的团簇同位素-温度转换方程。
关键词: 陆生蜗牛/
壳体碳酸盐/
团簇同位素/
古温度计/
古气候/
古环境

Abstract:The clumped isotopes in carbonate are a newly developed geothermometer, which can be used to more accurately constrain past temperature changes. Meanwhile, land snail shell fossils are an ideal archive for paleoclimatic study, with their faunal assemblages and stable carbon and oxygen isotopes revealing useful information on past environmental changes. Therefore, when being combined together, clumped isotopes in shell carbonate of land snail must serve as a powerful tool to quantitatively reconstruct paleotemperature. However, relevant study remains scarce, requiring us to take more effort to prompt the development of this research field. In this study, we initially introduced the concept and analytical method of carbonate clumped isotopes so that paleoclimate researchers can acquire some knowledge on this new proxy. Then we reviewed current progresses in studying clumped isotopes of land snail shell carbonate and pinpointed the existing questions in this aspect, and finally we took an outlook over future work. In brief, although clumped isotope temperature(T₄₇) of field-collected snails is systematically higher than their growing season temperature, the strong linear correlation of the two variables allows using snail-shell clumped isotopes to reconstruct environmental temperature during the growing season. However, there was inter-genera difference in T₄₇ among land snails at the same site(i.e., T₄₇ of Cathaica is about 3℃ higher than that of Bradybaena), rendering it necessary to use clumped isotopes-T transfer function at genera level when reconstructing paleotemperature using land snail fossils. Meanwhile, snail body water δ¹⁸O, which is calculated based on T₄₇ and shell oxygen isotope composition, can be interpreted as a paleo-hydrological indicator, reflecting isotopic composition of local precipitation. In addition, clumped isotopes data of land snails from loess strata indicated that there was an about 7~10℃ cooling in summer during last glacial period than at present in North China. This temperature amplitude, although need to be further validated, provides an independent evidence and reference for temperature changes at glacial-interglacial scale. Ongoing research is constructing clumped isotopes-T transfer function for the snail Punctum orphana because it shows continuous occurrence at different level of loess horizons and may be widely used for paleotemperature reconstruction.
Key words:land snail/
shell carbonate/
clumped isotopes/
paleo-thermometer/
paleoclimate/
paleoenvironment



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