This is a study of dolomite from Enewetak Atoll that employs new fluid inclusion techniques and standard techniques to develop a new model for dolomitization and to better understand the geochemical triggers responsible for dolomitization. Thorough study of Enewetak dolomite using traditional indirect techniques has proven less than adequate in constraining the model and geochemical triggers of dolomitization. Alternatively, fluid inclusions provide a direct record of the chemical composition of ancient dolomitizing fluids. Freezing techniques will be applied to the Enewetak fluid inclusions to determine the salinity of dolomitizing fluids. Reconnaissance data indicate that the dolomite precipitated from a brine that was twice the salinity of dolomitizing fluids. Reconnaissance data indicate that the dolomite precipitated from a brine that was twice the salinity of seawater. Thus, a new model for dolomitization involving reflux of brines that have not precipitated evaporites is one of several hypotheses to be tested. Laser Raman microprobe work will provide the first analyses of sulfate in an ancient fluid of low-temperature dolomitization. Extracts from fluid inclusions will be analyzed for cations and ions by DCP and IC to further characterize fluids of dolomitization. This new approach will provide new insight into fluid evolution and geochemical triggers of dolomitization. Such information cannot be gleaned by standard techniques. Lastly, the dolomite will be analyzed by standard carbon, oxygen, and strontium isotopic techniques to make the work directly comparable to other dolomite studies and to further evaluate conditions of dolomitization.
