PP046-0012
Reconstructing Environmental Temperature, Humidity, & δ18O Precipitation from Stable & Clumped Isotope Compositions of Global Land Snails
Wednesday, 16 December 2020
Poster
Hayley Lauren Bricker1, Jesse Bloom Bateman2,3, Bryce Mitsunaga1,4, John Arthur Mering1,5, Yurena Yanes6, Eric A Oches7, Robert Eagle8 and Aradhna E. Tripati1, (1)University of California, Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (2)SUNY Cortland, Biological Sciences, Cortland, NY, United States, (3)University of California, Los Angeles, Institute of the Environment & Sustainability, Los Angeles, CA, United States, (4)Brown University, Department of Earth, Environmental, and Planetary Sciences, Providence, RI, United States, (5)University of Waikato, Hamilton, New Zealand, (6)University of Cincinnati, Geology, Cincinnati, OH, United States, (7)Bentley University, Natural and Applied Sciences, Waltham, MA, United States, (8)University of California, Los Angeles, Atmospheric & Oceanic Sciences, Los Angeles, CA, United States
Abstract:
Stable isotope compositions of land snail shells provide insight into past changes in temperature and water balance. Importantly, these records can be applied to better understand climate responses in continental interiors across the Holocene. We explore the efficacy of clumped isotope (Δ47) and carbonate δ18O measurements in modern and Holocene land snails to determine if data from shell samples in the paleorecord can be used for paleo-climate and ecosystem reconstructions at regional to sub-regional scales. While snail shell clumped isotope records have been reported from a number of sites, the relationship between paleoenvironmental conditions, snail body water, and shell isotope signals need better validation. We carried out clumped isotopic measurements on land snail shells from three regions: the Chinese Loess Plateau, Central Europe, and the Canary Islands. Using Δ47 and δ18O as proxies, we calculate temperature of shell formation and snail body water balance, respectively. We then compare isotope results to environmental records of temperatures and precipitation δ18O. In order to constrain timing of shell growth we compare snail isotope-derived climate results to mean annual, warm season, and rainy season values.
T47 (°C) measurements fall within accepted optimal activity ranges (15-25 °C) for snail shell mineralization. Canary Islands samples are most consistent with year-round growth; the Chinese Loess Plateau samples are most consistent with summer growth; and the samples from central Europe are most consistent with spring or fall growth. Observed enrichments in body water δ18O relative to seasonal averages of meteoric δ18O are between 1‰ and 4‰ VSMOW. The land snails from the Canary Islands site of Lanzarote exhibit the least evaporative enrichment of all regions (~1‰ above local meteoric mean), and snail body water modeling supports shell growth at a relative humidity of ~95%. The land snails from both Central Europe and the Chinese Loess Plateau record the greatest enrichment (3‰ - 4‰ above meteoric mean), when applying relative humidity value ranges of 83-90% and 90-93%, respectively. Late Holocene samples from the Canary Islands yield similar T47 values, suggesting little change in temperature, with reconstructed microclimates that were more arid with a relative humidity that was ~10% lower.
