Geothermal convection: a mechanism for dolomitization at Enewetak Atoll?

Geothermal convection in carbonate platforms could drive massive dolomitization by supplying mass transport of magnesium over long periods and at temperatures high enough to overcome kinetic limitations. Reactive-transport simulations based on Enewetak Atoll show dolomitization in a thin band at a permeability contrast near the base of the platform, which is consistent with field observations of dolomitized Eocene deposits. Dolomitization is predicted at approximately 6% per My at temperatures of 45-60 degrees C, and complete dolomitization could be accomplished in similar to 16 My. Calcium enrichment of pare fluids and upward transport of these fluids is established early, prior to 30 ky. (C) 2000 Elsevier Science B.V. All rights reserved.