I have just received some results of d18O analyses done on freshwater
stromatolites (biogenic carbonates, and the water that they grew in. My
problem is, that after applying the equation relating temp to d180 for
calcite and d18O for waters(to test isotopic equilibrium), the equation
tells me the water was at 1.8degC, rather than the expected 13.2degC.

I'm thinking that there is some sort of biological fractionation going on.
Is this likely?, and has the effect been quantified for cyanobacteria or
diatoms?

Please help, my Honours thesis is due real soon.


Marc

|  Marc D. Kelly
|  Ph./ Fax: +61 (0)2 4965 3812
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|  Home: 13 William St., Hamilton, NSW, 2303, Australia.
|  Work: Dept. of Geography, University of Newcastle, Callaghan, NSW, 2308,
Australia.