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Date: | Tue, 11 Aug 1998 13:59:33 -0400 |
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>Please excuse me, I¥m a student of Chemistry at the Central Universty of
>Venezuela and I wanted to ask you some questions. I¥m working on my
>degree thesis and I would like to know the best delta value of oxigen in
>the Cretaceous in order to calculate paleotemperatures (I¥m working with
>-1 SMOW, my country had been for 200 millions years in the tropic) but I
>wanted to know a second opinion, also I¥m working with some calcite
>cristals wich could be from the Eocene (from geological evidence)wich
>would be the best value for oxigen. I¥m working with the O¥Neil (1969)
>ecuation since the are cements and not echinoderms, bivalbes.And the
>other question is:
>the laboratory where I made the stable isotopes analysis had not much
>experience in working with carbonates and I wanted to know if I have to
>make some corrections to the data they reported me ( the report has
>delta values of oxigen in PDB- SMOW and delta values of carbon in PDB),
>the tecnician in the laboratory does not know if the software of the
>equipment considered the fractionation factors:
>CO2-H2O= = 1,04012
>Acid liberated CO2-CO2 of calcite = 1,01025
>Acid - liberated CO2- PDB in equilibrium with SMOW = 1,00022
>All the measurements whrere made following the McCrea original method at
>25ƒC.
>Please forgive my bad English and thanks for any help you could give me.
>
>Daniel Alejandro Rivas Casanova
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