GEOCHEMICAL CHAOS: PERIODIC AND NONPERIDIC GROWTH OF MIXED- LAYER PHYLLOSILICATES

Interstratification – periodic or nonperiodic stacking of two different silicate layers along the c-axis – is common in phyllosilicates, although the mechanism for this is still unknown. In this paper, we show that the interstratification can autonomously emerge from a nonlinear mineral growth kinetics, which is described by a generalized logistic equation accounting for two countering factors: the saturation degree of solution and the strain energy between the two different structural components involved in the layer stacking. Chaotic interstratifcation occurs when the two structural components have a certain degree of dissimilarity and the solution is close to equilibrium with respect to each end-member phase. The chaos model proposed here has successfully predicted the associations of both mineral phases and layer sequences. Our work indicates that the transition from one interstratification mode to another reflects a change in chemical environment during phyllosilicate crystallization.