Are permineralized peats extinct soils? Are there other extinct soils?

Permineralized peats, also known as coal balls, are restricted in geologic time to the PermoCarboniferous. Why don’t they occur at other times? We are investigating the possibility that permineralization by calcite was drvien by CO2 escaping from peat swamp pore water through the air-filled rootlets of lycopsid trees, which dominated the biomass of these swamps. The figure to the left shows our simulated decrease of carbon dioxide (mmol/m³) that might have occurred in proximity to these unusual rootlets. Such rapid escape of carbon dioxide could have resulted in rapid calcite precipitation. If this model is correct then permineralized peats are ‘extinct’ because the lycopsid trees that formed them are extinct. This emphasizes the close relationship between vegetation and soil. This work has now been published.