Hi Andreas,

you may wish too look on the papers published by the collegues from Utrecht
on dolomite formation and brines.

To my personal experience, dolomite which, for instance, is found in the
hypersaline water column of the Urania basin is formed in-situ.
Considering a typical d18O (activity) value for deep brines of the Med of
about +2 permilles vs. SMOW (Stenni & Longinelli) you can compare your
measured data with those expected for isotope fractionation between water
and dolomite based on experimental and theoretical calibration curves
(e.g., Katz..., Fritz..., Golyshev..., Zheng and so on).

For dolomites from ODP Site 965 (Eratosthenes Seamount) I found d18O data
between +3.8 and +5.2 per milles vs. V-PDB (SR Leg 160).

Regards, Michael

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Dr. Michael E. Böttcher
Department of Biogeochemistry
Max-Planck-Institute for Marine Microbiology
Celsiusstr.1
D-28359 Bremen
Germany
Voice:  (+49)421-2028-632
Fax:    (+49)421-2028-580
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