Kinetics of illite formation

An activation energy of 19.6 +- 3.5 kcal/mole was found for conversion of synthetic beidellite with the composition Al/sub 2/Si/sub 3/./sub 66/Al/sub 0/./sub 34/O/sub 10/(OH)/sub 2/K/sub 0/./sub 34/ to mixed-layer illite/smectite. The size of this activation energy and the rate constants suggest that (1) the alteration of smectite to illite during diagenesis involves the breaking of chemical bonds in the 2:1 layers; (2) either an equilibrium or a kinetic interpretation for the range of mixed layering found in burial diagenetic sequences is compatible with the kinetic data; and (3) the formation of illite from smectite on the ocean floor will not be seen, even if the reaction is favored thermodynamically, because the reaction rate is too slow.