ABSTRACT

Although many researchers believe that most, if not all, dolomites are mainly formed by secondary replacement of limestones anywhere from soon after deposition, diagenesis, to now, a controversy over dolomite origin still remains. This is fueled by the fact that (a) thinly laminated wholly unfossiliferous dolomites closely associated with bedded anhydrite recur frequently in the stratigraphic record and (b) the discovery of Recent primary or evaporitic penecontemporanceous dolomites in the intertidal and supratidal regions of the Arabian Gulf, Florida, and the Bahamas, and other areas. Yet, no one has been able to synthesize dolomite in a laboratory simulating normal marine conditions; albeit experimental work at low temperatures has recently produced dolomite from solutions at pH's greater than 9.5 while maintaining high concentrations of SO₄ and NO₃. Now there is new evidence from carbonate geochemistry showing the precipitation of primary dolomites is related to kinetics or reaction rates.

End_of_Record - Last_Page 637-------