TITLE:
Influence of Mg2+, Fe2+ and Zn2+ Cations on 13C-18O Bonds in Precipitated Aragonite, Calcite and Dolomite: An ab Initio Study
AUTHORS:
Jie Yuan
KEYWORDS:
Metal Cation, 13C-18O Bond, Δ47, Phosphoric Acid, ab Initio Calculation
JOURNAL NAME:
Open Journal of Geology,
Vol.5 No.5,
May
11,
2015
ABSTRACT: The influence of metal
cations on 13C-18O
bonds in carbonates is still under debate. This paper used ab initio method to investigate this kind of influence
of Mg2+, Fe2+ and
Zn2+ cations on 13C-18O bonds in
precipitated aragonite, calcite and dolomite. The polynomials of Δ47 and reduced partition function ratios
(RPFRs) for 13/12C, 14/12C and 18/16O of these minerals
were given within temperatures ranging from 260 to 1500 K. We found that these
cations significantly decreased the Δ47 values at the level of 10-3 - 10-2 per mil, comparing with pure
crystals; and that if the Δ47 values
were used to reconstruct the temperatures Ts,
the deviation of T was about 7.2°C for, for instance,
zinc-enriched aragonite, as discussed in our paper. It was suggested that due
to such influence, researchers would better use a proper thermometer according
to the main impurity metal cations in carbonates. We also found that according
to the probability theory, the theoretical value of the influence of phosphoric
acid on Δ47 of CO2 degassed from different carbonates was
zero.