Late Pleistocene Diagenesis and Dolomitization, North Jamaica¹

SUMMARY Diagenesis, including dolomitization, of Late Pleistocene reefs of North Jamaica is due to reaction with meteoric water. Although the reactions: Mg‐calcite—calcite Aragonite—calcite Mg‐calcite—dolomite retain microarchitectural information, complete chemical redistribution takes place so that incongruently dissolved Mg‐calcites, aragonite inversion mosaics (neomorphosed aragonite), and dolomitized red algae have similar isotopic compositions, resembling precipitated calcite cements. The minerals all appear to have stabilized in the meteoric water environment. The dolomite is not widely distributed, and is restricted to replacement of red algae. There has been no net addition of magnesium to the red algal clasts.