Mechanisms of Inverse Transformations of Secondary Micas: Evidence from Changes in the Illite-Smectite Structure

摘要

As is evident from our previous publications [1,2], secondary micas of sedimentary rocks formed as a result of direct transformation of smectite into illite at any PT parameters of the environment are represented by blocks with some 3D periodicity of the structure [3] and may sometimes undergo inverse transformation [4]. Such a process accompanies breaking of particles of 3D mica into individual nanoplates with a high charge of the surface, which results in strong decrease of filtration and the appearance of stumps at the expense of electroosmotic counterflows during ejection of fresh waters in oil strata [4]. The portion of the smectite component vulnerable to swelling increases in mixed-layered illite-smectite synchronously. However, the mechanism of this process, especially of its early stages, has not been studied yet; there is no experimental estimation of the size of nanoblocks in the structure of secondary micas. This was prevented by the absence of analytical methods for real structures of intermediate products of inverse transformation.