Dolomite, a common rock minerals of the world, suffers from an “explanation gap.”
An article on PhysOrg admitted that a common type of rock widespread on earth remains little understood since it was first described over 200 years ago.
Not only in the Dolomites, but throughout the world dolomite is quite common. More than 90 percent of dolomite is made up of the mineral dolomite. It was first described scientifically in the 18th century. But who would have thought that the formation of this mineral is still not fully understood, although geologists are aware of large deposits of directly formed (primary) dolomite from the past 600 million years. The process of recent primary dolomite formation is restricted to extreme ecosystems such as bacterial mats in highly saline lakes and lagoons. “As these systems are very limited in space, there is an explanation gap for geologists for the widespread presence of fossil dolomite,” explains Dr. Stefan Krause, Geomicrobiologist at GEOMAR | Helmholtz Centre for Ocean Research Kiel.
However it formed, dolomite seems to have required vast quantities of bacteria. A recent paper is alleged to have brought “a light light” into the “darkness of this scientific riddle.” A team was able to get some dolomite to crystalize under conditions that prevail in the current oceans. But that raised a new question:
Evidence of primary dolomite formation by a process as common as microbial sulphate respiration under conditions that currently prevail in the seabed, provides new insights into the reconstruction of fossil dolomite deposits. But why are large scale deposits from primary dolomite no longer formed at the ocean floor? “Here we are still faced with a puzzle,” says Professor Tina Treude, head of the Working Group at GEOMAR. “One possibility is that massive primary dolomite can form particularly during times when large quantities of organic matter in the seabed are degraded by sulfate-respiring bacteria. Such conditions exist when the sea water above the seafloor is free of oxygen. In Earth’s history, several such oxygen-free periods have occurred, partly consistent with time periods of intensified dolomite deposition.”….
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