|
|
|
|
|
|
|
|
EGC-06 Geochemical proxies of palaeoenvironmental change in terrestrial environments
|
|
|
|
Stable isotopes in land snails and their environmental implications
|
|
|
|
Zhaoyan Gu, Institute of Geology and Geophysics, Chinese Academy of Sciences (China)
Naiqin Wu, Institute of Geology and Geophysics, Chinese Academy of Sciences (China)
Xiaohong Sun, Institute of Geology and Geophysics, Chinese Academy of Sciences (China)
Bing Xu, Institute of Geology and Geophysics, Chinese Academy of Sciences (China)
Yanwu Lu, Institute of Geology and Geophysics, Chinese Academy of Sciences (China)
Yongfu Chen, Institute of Geology and Geophysics, Chinese Academy of Sciences (China)
|
|
|
|
Carbon and oxygen stable isotope compositions of the land snail shell aragonite have a potential to indicate changes in climate and ecology. However, previous studies have shown that the shell aragonite isotope compositions would be affected by multi-factors. So, the land snail shell isotopic environmental implication is still unclear. To understand fully geochemical behaviors of stable isotopes in the land snails and to constrain the dominant factors influencing on their shell aragonite isotope compositions, isotopic analyses have been carried out on the shell aragonite and organic bodies of the live land snails from different sites of the Chinese loess plateau. The result gives us following features and clear implications.
First, there is a constant d13C difference between snail bodies and aragonite shells, supporting that the land snail dietary carbon isotope composition is a dominant factor controlling on 13C in the shell aragonite, and implicating that fossil shell aragonite d13C can reflect an isotopic signal of the snail diet.
Second, variations in d18O of same species shells grown from spring to autumn are parallel with monthly changes in local temperature, humidity, and rain d18O respectively, indicating that fossil snail shell aragonite d18O can be used as a proxy of climatic changes between cold-dry and warm-wet phases.
Third, both d13C and d18O of shell aragonite are different among different species of land snails from a locale. But, a good negative relationship presents between the d13C and d18O values from the different species, being deduced that land snail shell aragonite isotope composition would depend on its major active season.
Finally, the shell aragonite isotopic difference between different species changes with temperature and/or precipitation. It can be used as a proxy to reflect the bio-growing season length.
|
|
|
|
|
|
|
|
|
