Figure 5: | Scientific Reports

Figure 5

From: Generalized conditions of spherical carbonate concretion formation around decaying organic matter in early diagenesis

Figure 5

Constrained formation rate of spherical carbonate concretions. Relationship between effective diffusion coefficient (D; cm2/s) and growth rate of reaction front (V; cm/s) shows the narrow range of formation conditions of spherical concretions. Taking an effective diffusion coefficient for HCO3 of 10−6 cm2/s, which is a mean value for similar kinds of clayey marine sediments together with the observed variation in reaction front thickness in small (mean values L1 to L3) to gigantic concretions (estimated values L4 to L6) shows that the growth rates of the spherical concretions was between 10−5 and 10−7 cm/s and that the concretions formed very rapidly early in diagenesis.