Rhizoliths and Signs of Pedogenesis in the Late Permian of Central Russia

Abstract

The remains of fossil roots (rhizoliths) of two morphotypes (M1 and M2) are described from Upper Permian deposits near the town of Vyazniki in the east of Vladimir region. In the section, M1 rhizoliths are vertically oriented and represented by several types of preservation: rhizocretions, imprints of the root surface, and root petrifactions. The study of the transverse and longitudinal sections of ferruginized root fragments has shown that the structure of the central conducting bundle (stele) can be of three types. It is observed that the branching areas of the lateral roots are arranged into four rhizostichies, indicating a tetrarchic type of stele for these roots. The discovery of the remains of root systems in an upright position and without any traces of transportation indicate the first stages of primary soil formation. M2 rhizoliths are a network of finely intertwined roots. The new finds of in situ rhizoliths significantly complement our understanding of the Late Permian paleoenvironments and paleoecosystems in the center of the Russian Platform.