Figure 2.

Porespace and mineral-facilitated biogenesis. In the multiply connected porespace between sedimented mineral grains (left panel), water can flow in various directions. Confluent layers of biogenic organic hydrogels (right panel, green) accumulate and progressively cover much of the mineral surface, whilst water can still move back and forth through most channels in the porespace network. The organic matrix does not only spread by incremental growth, but also by turbulent currents that redistribute the upper layers of the sediment. This diagram emphasizes the connectivity throughout a contiguous porespace. It does not, however, represent the nanoscale roughness and heterogeneity of the catalytically important mineral grains.