Smectite/illite transition

Buatier MD, Peacor DR, O Neil JR (1992) Smectite-illite transition in Barbados accretionary wedge sediments TEM and AEM evidence for dissolution/crystallization at low temperature. Clays Clay Minerals 40 65-80... 

Mixed-layer clays, particularly illile-smeclite. are very common minerals and illustrate the transitional nature of the 2 1 layered silicates. The transition from smectite to illite occurs when smectite, in the presence of potassium front another mineral such as potassium feldspar, or from thermal fluids, is heated and/or buried. With increasing temperature smectite plus potassium is convened to illite. 

Anchizone after Kibler (1964, 1968), a transitional zone between the diagenetic zone and the epizone as defined by IC mean values between 0.42 and 0.25 A°20. [Kaolinite and/or dioctahedral illite/smectite interstratified clay mineral with more than about 10% expandable layers are absent in normal clastic rocks, but they may persist in carbonate rocks, and in organic matter-rich, Na-rich and K-poor shales.]... 

Mineral transformations during diagenesis (e.g., illite smectite transition), metamorphism (e.g., recrystallization of clay minerals to biotites, amphiboles, etc) or alteration (e.g., serpentinization of mafic minerals) are likely to release the radiogenic noble gases that were produced within their lattices. This assumes that ... 

Fig. 4.1. Transformation of mixed-layer days of illite-smectite types (unordered) into ordered phase of vermiculite-chlorite type vs. transition of Fe into Fe. Paleozoic sediments of the Illizi Basin...

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