Sector zoning in calcite cement crystals: Implications for trace element distributions in carbonates

Compositional sector zoning in calcite cement crystals from a sedimentary limestone is represented by differences of Mg content of over 1300 ppm, or 95%, and of Sr and Mn contents of up to 400 ppm, or roughly 50% and 80% respectively, between crystallographically nonequivalent, time-synchronous growth sectors. {1011} sectors are enriched with both Mg and Mn relative to {1014} sectors, and other sectors show both greater and lesser enrichment. This systematic zoning pattern requires effective distribution coefficients for these trace elements to have been different for growth on different faces. Differential growth rate effects for nonequivalent faces are shown to be unimportant relative to differential growth face element preferences. Surface crystal structure and differing coordination environments are regarded as the principal factors influencing sector-related elemental partitioning differences in calcite and dolomite.