2 nd international workshop on clumped isotopes, London, August 10-12 2011
Robert A. Eagle 1,* , Aradhna K. Tripati 2,3 , John M. Eiler 1 , Gaojun Li 4 , Xuefen Shen 4 ,
Jun Chen 4
1) Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena,
CA, USA
2) Department of Earth and Space Sciences & Department of Atmospheric and Oceanic
Sciences, University of California, Los Angeles, CA, USA
3) Institute of the Environment and Sustainability, University of California, Los Angeles, CA, USA
4) Department of Earth Sciences, Nanjing University, Nanjing, China
* Corresponding author : robeagle@caltech.edu
A variety of archives including speleothem, lake, marine, and loess deposits have revealed that the East Asian Monsoonal system exhibits significant variations on orbital and suborbital timescales. For example, precisely-dated speleothems from caves in
China exhibit glacial-interglacial fluctuations in carbonate  18 O values of ~4 per mil.
However it is unclear exactly what fluctuations observed in these and other monsoonal proxy records reflect, with possible contributions of temperature, vapor source, amount effects, changing winter vs summer monsoon intensity, and kinetic isotope fractionations to carbonate  18 O records. We have applied clumped isotope thermometry to terrestrial gastropod shells from well-dated Chinese loess deposits to constrain glacial-interglacial temperature and water isotope shifts. We have made over
120 sample analyses in order to provide robust statistical constraints on the data.
Variations within populations are larger than expected based on the error of replicate measurements. The clumped isotope data for samples from each time period are indistinguishable from a normal distribution and indicate significant glacial-interglacial temperature variations. These data also allow us to constrain shifts in the isotopic composition of local meteoric waters. The distribution of temperatures and water  18 O values from glacial intervals has greater kurtosis (spread) than the distribution of observed in modern samples, which may be a possible indication of increased climate instability during glacials
.
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