The small intracratonic Cheb (Eger) Basin in NW Bohemia (Central Europe) is characterized by swarm earthquakes, many mineral springs and mofettes with upper mantle CO2 degassing and by neotectonic graben and basin structures. Especially in non-lithified Upper Pliocene clay formations of the basin, a variety of deformation patterns is exposed. They include non-tectonic and tectonic activity and comprise faulting and folding from µm- to km-scale. Previously unrecognized N-S- and ENE-striking faults are sites of mantle degassing and seismic activities. Confined-layer deformation and liquefaction structures hint to palaeoseismic events and gas escape activity. Cleavage-like arranged clay mineral plates represent the microfabric of clay within fault zones. For the first time the degassing channels of Upper Mantle fluids/gases through the Pliocene clay sediments can be documented: µm-scale micro-tubes were produced by the opening of Riedel shear planes induced by fault movements.

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In the kaolin deposit near Rønne on the island of Bornholm in the Baltic Sea a number of well-rounded, unweathered, boulder-like relicts of the granodioritic parent rock are found, embedded in kaolin. Samples have been taken of one relict at 2 cm interval from the fresh material outwards into the kaolin. The distribution pattern of the major elements in these samples has been studied in order to gain an impression of the leaching conditions at the time of formation, in the immediate vicinity of the relict. This distribution shows on a minor scale, what previously has been demonstrated in bulk for the whole deposit that leaching effects have not been uniform for the different elements, leading to a relative enrichment of calcium in the transition zone close to the unweathered parent rock. TEM and SEM observations revealed that halloysite and smectite are the dominant clay minerals of the transition zone, where kaolinite occurs only sporadically. These minerals apparently become unstable when alkalis and alkali earths are progres­sively leached, while kaolinite emerges as the pincipal clay mineral, and amphibole and plagioclase no longer remain in the residual mineral assemblage.