Acta Geodyn. Geomater., Vol. 6, No. 1 (153), 13–43, 2009 PHYLLOSILICATES IN THE SEDIMENT-FORMING PROCESSES: WEATHERING, EROSION, TRANSPORTATION, AND DEPOSITION Jiří KONTA Faculty of Sciences, Charles University, Albertov 6, 128 43 Prague 2 Home address: Korunní 127, 130 00 Prague 3, Czech Republic *Corresponding author‘s e-mail:
[email protected] (Received October 2008, accepted January 2009) ABSTRACT Phyllosilicates are classified into the following groups: 1 - Neutral 1:1 structures: the kaolinite and serpentine group. 2 - Neutral 2:1 structures: the pyrophyllite and talc group. 3 - High-charge 2:1 structures, non-expansible in polar liquids: illite and the dioctahedral and trioctahedral micas, also brittle micas. 4 - Low- to medium-charge 2:1 structures, expansible phyllosilicates in polar liquids: smectites and vermiculites. 5 - Neutral 2:1:1 structures: chlorites. 6 - Neutral to weak-charge ribbon structures, so-called pseudophyllosilicates or hormites: palygorskite and sepiolite (fibrous crystalline clay minerals). 7 - Amorphous clay minerals. Order-disorder states, polymorphism, polytypism, and interstratifications of phyllosilicates are influenced by several factors: 1) a chemical micromilieu acting during the crystallization in any environment, including the space of clay pseudomorphs after original rock-forming silicates or volcanic glasses; 2) the accepted thermal energy; 3) the permeability. The composition and properties of parent rocks and minerals in the weathering crusts, the elevation, and topography of source areas and climatic conditions control the intensity of weathering, erosion, and the resulting assemblage of phyllosilicates to be transported after erosion. The enormously high accumulation of phyllosilicates in the sedimentary lithosphere is primarily conditioned by their high up to extremely high chemical stability in water-rich environments (expressed by index of corrosion, IKO).