High-temperature Experiment on Transformation from Aragonite to Calcite in Land Snail Shells and Its Impact on Carbon Isotope Composition Variations(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2018年第03期
- Page:
- 275-284
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- High-temperature Experiment on Transformation from Aragonite to Calcite in Land Snail Shells and Its Impact on Carbon Isotope Composition Variations
- Author(s):
- LI Cheng-long; SHENG Xue-fen; BAO Rui; LUO Ling; JI Jun-feng
- 1. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, Jiangsu, China; 2. Key Laboratory of Surficial Geochemistry of Ministry of Education, Nanjing University, Nanjing 210023, Jiangsu, China
- Keywords:
- biogeochemistry; snail; high-temperature heating; aragonite; calcilization; H2O2 treatment; carbon isotope composition; paleoclimate reconstruction
- PACS:
- P593
- DOI:
- -
- Abstract:
- The stable isotope compositions of biogenic calcium carbonate are often used as an important proxy for the studies of past global climate change; however, a significant isotope bias during the transformation from aragonite to calcite would affect the quantitative reconstruction of paleoclimate. The experiments were conducted under the air conditions by high-temperature heating the aragonite shells of land snail Achatina fulica, and the various of contents of calcite and carbon isotope compositions before and after heating were revealed. The results show that the contents of calcite increase with the temperature increasing; the transformation from aragonite to calcite is affected by the content of organic matter of the shells; the contents of calcite are lower in the samples without H2O2 treatment than those in the samples with H2O2 treatment under the condition of the same heating temperature and time; the heating process can cause the samples with lower carbon isotope compositions than the original samples; the temperature in the short-time heating plays an important role in the transformation from aragonite to calcite, and the H2O2 could play a role in the transformation; the lower carbon isotope compositions in the heated samples could be due to the carbon isotope exchange reaction between the samples and CO2 in the air, not due to the phase transformation. Hence, the isotope bias induced by phase transformation and isotope exchange should be taken into consideration when the carbon isotope compositions of land snail shells are used to reconstruct paleoclimatic history.
Last Update: 2018-06-05