“Dolomite Problem” and Research of Ancient Lacustrine Dolostones

Key words: 
• microbial dolomite /
• lowtemperature precipitation /
• micromorphology /
• scale of microbial dolomite /
• ancient lacustrine dolostones

Abstract: In the past thirty years，microbial dolomite model provides a new insight into longstanding “Dolomite Problem”. Many experiments and cases demonstrated that the metabolic activities of microorganisms (sulfatereducing bacteria, methanogenic Archaea, and moderately halophilic aerobic bacteria, etc.) played a key role in mediating the dolomite lowtemperature precipitation. The characteristic microtexture, micromorphology and specific carbonate isotopes are the major distinguishing remarks of the microbial dolomite. However，there have stillcontroversies on the scale of microbial dolomite, its mediation mechanism, whether there exist putative "nanobacteria" fossils, and whether the modern microbial dolomite model can be reliable criteria to ancient analogues. Ancient lascustrine dolostones widespread in China which show a diversity of mechanisms, offer good opputinities to better understand these intensive issues in comparison with the modern counterparts.