Synthetic studies of protodolomite from brine waters

Abstract

Synthetic studies of protodolomite were carried out for understanding the conditions of protodolomite formation in sedimentary environments. Protodolomite was tried to be precipitated from concentrated sea water (by evaporating sea water) by adding 0.4M-Na2CO3solution drop by drop. The obtained minerals were amorphous carbonate, aragonite, Mg-poor calcite, Mg-rich calcite, protodolomite, huntite, monohydromagnesite, monohydrocalcite and trihydrocalcite, depending on the concentrations of calcium and magnesium ions in the brine water, the added amount of sodium carbonate and reaction time. Protodolomite seems to be formed diagenetically from metastable minerals given above. The concentration of carbonate ions, Mg2+/Ca2+ratio and temperature in a parent solution have an important influence on the formation of calcite type carbonate minerals and the Mg contents of these minerals. © 1983, GEOCHEMICAL SOCIETY OF JAPAN. All rights reserved.