Trace element and PGE distribution in layered ferromanganese crusts

A collection of layered ferromanganese ores (27 samples) from the Atlantic and Pacific oceans was studied. Trace element and PGE contents were determined layer-by-layer (up to 10 microlayers) in 13 of these samples.The trace, rare earth, and platinum group element distributions, including their layer-to-layer variations, were compared in hydrogenic and hydrothermal crusts from different regions. It was found that the main PGE variations (by a factor of 10–50) are related to their layer-to-layer variations within a given ore field.The distributions of PGE and trace elements are strongly heterogeneous, which is related, first, to different contents of the elements in the layers of different age in ferromanganese crusts (FMC) and, second, to the observed regional heterogeneity and influence of hydrothermal fluids. Geochemical data indicate that CFC formation was mainly caused by the hydrochemical precipitation of material from seawater. This process was accompanied by diagenetic phenomena, water-rock interaction, and influence of volcanic and hydrothermal sources.     

Late Carboniferous lycopsids of the Karantrav locality (the Southern Urals)

Numerous plant remains as the imprints of lycopsid strobili and stems and the sporadic imprints of articulate stems were first found in the Upper Carboniferous deposits from the Western Slope of the Southern Urals (Karantrav Settlement area). The brief stratigraphic characteristic of the studied locality is given. The studied plant assemblage is represented by Lepidodendron ophiurus Brongniart, L. vaselgense Anikeeva et O. Orlova, sp. nov., Lepidodendron sp., Lepidostrobus tevelevii O. Orlova, Mamontov et Anikeeva, sp. nov., L. ronnaensis Bek et Oplustil, Knorria sp., Calamites sp., and Mesocalamites ramifer (Stur) Hirmer. In-situ microspores of the Lycospora type were discovered in the sporangia of some strobili of the genus Lepidostrobus. Four lycopsid species (two are new) were described.     

Evolutionary Stages of Riphean Sedimentary Basins in the Central East European Platform (with Kresttsy and Pavlov Posad Sedimentary Basins as an Example)

The Riphean Kresttsy and Pavlov Posad sedimentary basins, which occupy different positions in the East European Platform (EEP) are considered. Compositional features of terrigenous–mineral associations (TMA) of sedimentary complexes in these basins and their relation to the intrabasin and external sources of the detrital material are revealed. Two (preaulacogen and aulacogen) stages in the development of Riphean sedimentary basins in the central EEP are established. Relics of preaulacogen sequences are recorded only at the base of the sedimentary succession in the Pavlov Posad basin. These two basins formed at the aulacogen stage under an influence of strike-slip stresses. Aulacogen sequences of the Pavlov Posad basin formed in one stage, whereas sequences of the Kresttsy basin accumulated during two stages.