Source: Dan Hawkes
The concentrations of Sr, Mg, and other elements in calcite are
widely used to infer the conditions of mineral growth. However, such
inferences are dependent on the mechanisms that govern the incorporation
of minor constituents into the calcite lattice during growth. A team of
investigators (including former ESD Division Director Don DePaolo) show
that the growth rate dependence of Sr and Mg incorporation into
calcite, as well the inhibitory effects on calcite growth of both
incorporating and non-incorporating ions, can be predicted with an
ion-by-ion crystal growth model where ion attachment is confined to kink
sites on the crystal surface. This model should be widely applicable
for understanding the impurity content of a large range of sparingly
soluble minerals that form by precipitation from aqueous solutions.
The research was done as part of the Center for Nanoscale Control of
Geologic CO2, a Basic Energy Sciences Energy Frontier Research Center.
General support for isotopic geochemistry is also provided by Chemical
Sciences, Geosciences and Biosciences Division, Office of Science,
Office of Basic Energy Sciences, of the U.S. Department of Energy under
Contract No. DE-AC02-05CH11231.
For more information, go to: http://www.sciencedirect.com/science/article/pii/S0016703713002160
Citation: Nielsen, L.C., J.J. De Yoreo, and D.J. DePaolo (2013),
General model for calcite growth kinetics in the presence of impurity
ions. Geochimica et Cosmochimica Acta, 115, 100–114; DOI:
Funding: BES, NCGC-EFRC