Critical Problems for Dolomite Formation and Dolomitization Models

Increasingly significant proportions of the hydrocarbons all over the world,including China,are found in dolomite reservoirs.Nevertheless,in despite of more than 200 years of efforts,the dolomite problem-the geneses of dolomite(Warren,2000) still remains disputable.Most critical observations and conclusions available are: ① evidences revealed that the dolomite mostly formed by secondary replacement,i.e.dolomitization processes,② it is kinetic factors rather than thermodynamics that restrain the lower temperature syntheses of dolomite precipitates,③ the sources and the volume of Mg-rich fluids control the extent and scale of dolomitization,and ④ microbial activities may be another important factor of favoring the formation of dolomite.To explain different forms of dolomite,many models are proposed in literatures,focusing on the conditions and the locations of the interaction of the Mg-rich fluids with the preexistent calcareous carbonates.Generally speaking,condensed marine water dolomitization,Sabkha model,mixing-zone dolomitization and burial adjustment are relatively of great importance.