Trace and minor element distributions have played a major role in interpreting carbonate mineral formation and diagenesis in sedimentary environments. Sorption and coprecipitation processes involving carbonates also figure importantly in controlling trace metal concentrations in near-surface waters. However, major limitations in efforts to model such processes quantitatively result from a poor understanding of factors that influence partitioning of elements between aqueous solutions and carbonate minerals, especially the abundant mineral calcite. Findings that surface crystal structure, and particularly the geometry and structure of growth steps, exert strong influences on selective element incorporation, offer a means by which to examine the very surface mechanisms that cause such selectivity in partitioning. By correlating surface structural features imaged by differential interference contrast microscopy with quantitative trends of selective enrichment for various elements over a range of conditions, the relative influences of growth rate and surface structure on element partitioning will be evaluated. The present research project will provide insight to the most fundamental mechanisms operating during crystal growth, specifically those factors that influence trace and minor element distribution. In addition, this research will lead to a capability of predicting differential partitioning trends that are element specific and their associated crystal growth rate effects.
